tag:blogger.com,1999:blog-14682785181160804432024-02-07T02:22:54.124-08:00FM TRANSMITTER ANTENNA RESOURCESUnknownnoreply@blogger.comBlogger35125tag:blogger.com,1999:blog-1468278518116080443.post-7359543116281470992014-07-04T04:27:00.001-07:002014-07-04T04:27:35.313-07:00A Transmitter Circuits<p><a href="http://www.alphalink.com.au/%7Eparkerp/projvalv.htm">1 Valve 3.5MH CW Transmitters</a>: <p><a href="http://w1.859.telia.com/%7Eu85920178/tx/1tubetx.htm">1 Valve CW Transmitter</a>: <p><a href="http://www.uoguelph.ca/%7Eantoon/circ/tx15trak.htm">1.5 Volt Tracking Transmitter</a>: <p><a href="http://www.reconnsworld.com/transmit_tracker1.html">1.5 Volt Tracking Transmitter 2</a>: <p><a href="http://w1.859.telia.com/%7Eu85920178/tx/15w-pa.htm">10W HF Linear Amplifier</a>: <p><a href="http://w1.859.telia.com/%7Eu85920178/tx/v7b_proj.htm">150mW FM Transmitter</a>: <p><a href="http://www.electronicsteacher.com/circuitos.tripod.cl/schem/r75.gif">1W CW Transmitter</a>: <p><a href="http://www.zen22142.zen.co.uk/Circuits/rf/2bjttx.htm">2 Transistor FM Transmitters</a>: <p><a href="http://www.zen22142.zen.co.uk/Circuits/rf/2bjttx.htm">2 Transistor FM Transmitters</a>: <p><a href="http://www.electronicsteacher.com/www.alphalink.com.au/_parkerp/2v40.gif">2 Valve 40m CW Transmitter</a>: <p><a href="http://w1.859.telia.com/%7Eu85920178/tx/2tubetx.htm">2 Valve CW Transmitter</a>: <p><a href="http://www.electronicsforu.com/electronicsforu/Lab/freecircuitslist.asp?id=275">20M, 4W QRP Transmitter</a>: <p><a href="http://w1.859.telia.com/%7Eu85920178/tx/250mwtx.htm">250mW HF CW Transmitter</a>: <p><a href="http://w1.859.telia.com/%7Eu85920178/tx/cw-am_00.htm">27MHz AM/CW Transmitter</a>: <p><a href="http://www.io.com/%7En5fc/2n2222.htm">2N2222 40 Meter CW / DSB Tranceiver</a>: <p><a href="http://www.aaroncake.net/circuits/3Wfmtran.htm">3 Watt FM Transmitter </a>: <p><a href="http://www.uoguelph.ca/%7Eantoon/circ/30m.htm">30 Meter QRP Transmitter for Morse Code</a>: <p><a href="http://w1.859.telia.com/%7Eu85920178/tx/linear.htm">3W HF QRP Linear Amplifier</a>: <p><a href="http://www.uoguelph.ca/%7Eantoon/circ/txtrack.htm">4 Transistor Tracking Transmitter</a>: <p><a href="http://www.zen22142.zen.co.uk/Circuits/rf/4txtr.htm">4 Transistor Transmitter</a>: <p><a href="http://www.electronicsteacher.com/www.vekoll.vein.hu/_jap/electronic/tx434.gif">433MHz Transmitter using SAW Resonator</a>: <p><a href="http://w1.859.telia.com/%7Eu85920178/tx/5watttx.htm">5 Watt HF CW Transmitter</a>: <p><a href="http://w1.859.telia.com/%7Eu85920178/tx/qrp-hf1.htm">500mW HF Linear Amplifier</a>: <p><a href="http://www.wa4dsy.net/">56K RF Modem</a>: <p><a href="http://www.nrgkitsfm.com/workshop/early_stereo_5watt_pll_radio_jukebox.htm">5W PLL Transmitter</a>: <p><a href="http://www.designnotes.com/CIRCUITS/amcwrad.htm">7Mhz AM/CW Amateur Radio Transmitter</a>: <p><a href="http://www.dl5neg.de/7mhz_trx/40m_trx.htm">7MHz QRP Transmitter</a>: <p><a href="http://www.flashwebhost.com/tcvr/index.php">7MHz SSB Transceiver</a>: Circuit digram and brief description of 7MHz SSB Transceiver for Hams. The circuit is designed around two numbers of MC1496. It can push around 80 Watts with IRF840 in the final. You can down load HTML version or the printer friendly word document. <p><a href="http://www.alphalink.com.au/%7Eparkerp/proj80ds.htm">80 Meter DSB Transmitter</a>: <p><a href="http://www.flashwebhost.com/circuit/807_and_1625_valves.php">807 and 1625 Valves</a>: data on vacuum tubes 807 and 1625 used in ham radio transmitters. Describes various pin voltages and different operation modes. <p><a href="http://www.flashwebhost.com/circuit/dsb_transmitter_for_hams.php">AM DSB Transmitter for Hams</a>: circuit diagram of simple double side band suppressed carrier (DSBSC) transmitter for hams. Circuit uses crystal oscillator, crystal can be switched for multi band operation. . <p><a href="http://www.electronicsteacher.com/circuitos.tripod.cl/schem/r63.gif">AM oscillator for Wireless Microphones</a>: <p><a href="http://www.zen22142.zen.co.uk/Circuits/rf/amtx.htm">AM Transmitter</a>: <p><a href="http://www.flashwebhost.com/circuit/antennas_for_ham_transmitters.php">Antennas for Ham Transmitters</a>: Describes how to construct various type of antenna for Ham Radio Transmitters. <p><a href="http://lea.hamradio.si/%7Es51kq/ATVRC-1.HTM">AT Volt Repeater Controllers</a>: <p><a href="http://members.tripod.com/xexorz/schematics/fmtrans1.html">Basic FM Radio Transmitters</a>: <p><a href="http://www.uoguelph.ca/%7Eantoon/circ/rfosc-1.htm">Basic RF Oscillator #1</a>: <p><a href="http://www.electronicsteacher.com/www.geocities.com/archilochus57/images/rftx.gif">Basic RF Transmitter for PIR Sensors</a>: <p><a href="http://users.cableaz.com/%7Ecappels/dproj/FMdist/fmdis.htm">Battery operated FM rebroadcast transmitter </a>: Gives you 10 to 20 meters range and runs for months on a single penlight cell. <p><a href="http://www.flashwebhost.com/circuit/ceramic_filter_bfo.php">Ceramic Filter BFO</a>: Receive SSB and CW transmissions on your BC receiver. Simple BFO is build around 455 KHz Ceramic Filter. <p><a href="http://w1.859.telia.com/%7Eu85920178/tx/v6_00.htm">Crystal Controlled FM Transmitter</a>: <p><a href="http://www.elecdesign.com/Articles/ArticleID/4601/4601.html">Current Transmitter With Linear Voltage Transfer Rejects Ground Noise</a>: 08/07/00 Electronic Design - Ideas for Design / Many systems use current signals to control remote instruments. The advantage of this method is the ability to operate with two remotely connected power supplies even if their grounds are not the same. In these cases, it's necessary for the output. . . <p><a href="http://www.qsl.net/kd2bd/exciter.html">Design of Brookdale AT Volt Repeater System Exciter</a>: uses a pair of Hamtronics model TA4512-watt narrow-band FM voice transmitters to develop video and audio carriers on439.250 MHz and443.750 MHz <p><a href="http://w1.859.telia.com/%7Eu85920178/tx/fm-tx1.htm">Easy 2 Meter Transmitter</a>: This project is a simple transmitter using only one crystal and will cover 145.00 to 146.00 MHz. The crystal is a 44.9333 MHz crystal for 145.500 receive, as used in the Trio (Kenwood) 2200, PYE, Motorolla, Tait equipment, to name but four. The frequency of the crystal is not critical as almost any other xtal for the 2-meter band will function <p><a href="http://www.electronicsteacher.com/circuitos.tripod.cl/schem/r13.gif">Experimental Data Transmitter for Fiber optics</a>: <p><a href="http://www.electronicsteacher.com/circuitos.tripod.cl/schem/r13.gif">Fibroptic transmitter </a>: <p><a href="http://www.wenzel.com/pdffiles/fmxmit.pdf">FM Band Monaural Transmitter</a>: <p><a href="http://ourworld.compuserve.com/homepages/Bill_Bowden/page6.htm#fm.gif">FM Beacon Transmitter (88 108 MHz)</a>: This circuit will transmit a continuous audio tone on the FM broadcast band (88-108 MHz) which could used for remote control or security purposes. Circuit draws about30 mA from a 6-9 volt battery and can be received to about100 yards. <p><a href="http://users.cableaz.com/%7Ecappels/dproj/FMXMTR/fmxmtr.htm">FM Broadcast Audio Transmitter </a>: Monophonic FM band transmitter for home use. <p><a href="http://w1.859.telia.com/%7Eu85920178/tx/bug2.htm">FM Bug</a>: <p><a href="http://www.electronicsteacher.com/circuitos.tripod.cl/schem/r112.gif">FM Radio Bug</a>: <p><a href="http://www.ee.washington.edu/conselec/Sp96/projects/mst/final/fnlrpt.htm">FM Radio Telephone Transmitter</a>: <p><a href="http://www.zen22142.zen.co.uk/Circuits/rf/davidtx.htm">FM Radio Transmitter</a>: <p><a href="http://www.e-insite.net/ednmag/contents/images/33000di.pdf">FM Radio Transmitter #1</a>: <p><a href="http://www.zen22142.zen.co.uk/Circuits/rf/txcct.htm">FM Radio Transmitters With OpAmp </a>: <p><a href="http://www.zen22142.zen.co.uk/Circuits/rf/2bjttx.htm">FM Transmitter</a>: <p><a href="http://www.electronicsteacher.com/circuitos.tripod.cl/schem/r35.gif">FM transmitter </a>: <p><a href="http://www.glolab.com/freeinfo/k4a.pdf">Four Channel Wireless Transmitter & Receiver</a>: <p><a href="http://www.uoguelph.ca/%7Eantoon/circ/txtrack.htm">Four Transistor Tracking Transmitter</a>: <p><a href="http://www.electronicsteacher.com/www.alphalink.com.au/_parkerp/lunch.gif">Frequency Agile 80m CW QRP Transmitter</a>: <p><a href="http://w1.859.telia.com/%7Eu85920178/tx/bug5.htm">High Power FM Bug</a>: <p><a href="http://www.vekoll.vein.hu/%7Ejap/electronic/codec.html">Infra / Radio Remote Control Transmitter / Receiver</a>: <p><a href="http://www.geocities.com/zs6bne/circuits.htm">Infrared Transmitter and Receiver Schematic Diagrams</a>: <p><a href="http://www.hut.fi/Misc/Electronics/circuits/ir_send.html">Infrared Transmitter Circuit</a>: <p><a href="http://members.tripod.com/xexorz/schematics/irtransmit.html">Infrared Transmitter for Audio</a>: (Amplitude Modulated IR) <p><a href="http://www.electronicsteacher.com/circuitos.tripod.cl/schem/r94.gif">Laser Diode Transmitter</a>: <p><a href="http://www.g0mrf.freeserve.co.uk/laser4.htm">Laser Transmitter Schematics</a>: <p><a href="http://www.uoguelph.ca/%7Eantoon/circ/rftls.htm">Light Sensing RF Transmitter</a>: <p><a href="http://antiqueradio.org/schemat.htm">Li'l 7 AM Transmitter Schematic</a>: <p><a href="http://www.electronicsforu.com/electronicsforu/Lab/freecircuitslist.asp?id=15">Long Range FM Transmitter</a>: <p><a href="http://www.sound.au.com/project54.htm">Low Power FM Transmitter</a>: <p><a href="http://ourworld.compuserve.com/homepages/Bill_Bowden/page6.htm#amtrans.gif">Micro Power AM Broadcast Transmitters</a>: In this circuit, a 74HC14 hex Schmitt trigger inverter is used as a square wave oscillator to drive a small signal transistor in a Class C amplifier configuration. The oscillator frequency can be either fixed by a crystal or made adjustable VFO with a capacitor/resistor combination. <p><a href="http://www.uoguelph.ca/%7Eantoon/circ/uspy.htm">Micro Spy With FETs</a>: <p><a href="http://www.uoguelph.ca/%7Eantoon/circ/uspy3.htm">Micro Spy With TTL</a>: <p><a href="http://www.uoguelph.ca/%7Eantoon/circ/uspy2.htm">Micro Spy With USW</a>: <p><a href="http://www.solorb.com/gfc/elect/microfm/index.html">MicroPower FM Broadcasting Circuits</a>: <p><a href="http://www.uoguelph.ca/%7Eantoon/circ/fmt2.htm">Miniature FM Transmitter #2</a>: <p><a href="http://www.uoguelph.ca/%7Eantoon/circ/fmt3.htm">Miniature FM Transmitter #3</a>: <p><a href="http://www.uoguelph.ca/%7Eantoon/circ/fmt4.html">Miniature FM Transmitter #4</a>: <p><a href="http://www.reconnsworld.com/transmit_fm_trasm.html">Miniature FM Transmitters #4</a>: <p><a href="http://www.flashwebhost.com/circuit/miniature_mw_transmitter.php">Miniature MW Transmitter</a>: circuit diagram of simple medium wave transmitter using BF494B. This simple transmitter have a range of 200 meters. . <p><a href="http://www.p5taylor.btinternet.co.uk/8.pdf">MINIATURE TRANSMITTER</a>: What can I say about this circuit except brilliant I have actually built this one and was very impressed, I built it using leaded components maybe one day try a bit of smd make it even smaller, problems needs a big Ariel to transmit over any great distance. <p><a href="http://www.alphalink.com.au/%7Eparkerp/projvalv.htm">One Valve 3.5MH CW Transmitter</a>: <p><a href="http://www.zen22142.zen.co.uk/Circuits/rf/txcct.htm">Op Amp Based FM Transmitter</a>: <p><a href="http://w1.859.telia.com/%7Eu85920178/tx/p-ssb.htm">Phasing SSB Exciter</a>: <p><a href="http://w1.859.telia.com/%7Eu85920178/tx/hf-osc1.htm">QRP HF Transmitter</a>: <p><a href="http://www.flashwebhost.com/circuit/cwkeyer.php">QRP Keyer</a>: very simple keyer circuit using only one transistor. <p><a href="http://w1.859.telia.com/%7Eu85920178/tx/ssb-tx1.htm">QRP SSB Transmitter</a>: <p><a href="http://www.electronicsforu.com/electronicsforu/lab/freecircuitslist.asp?id=334">Quality FM Transmitter</a>: <p><a href="http://www.uoguelph.ca/%7Eantoon/circ/rftls.htm"><="" a="" size="2">: </a> <p><a href="http://www.sss-mag.com/pdf/hhopsch.pdf"><="" a="" size="2">:</a> <p><a href="http://www.reconnsworld.com/transmit_sens_fmt.html">Sensitive FM Transmitter</a>: <p><a href="http://www.designnotes.com/CIRCUITS/transmitshortwave.htm">Shortwave Radio Transmitter</a>: <p><a href="http://www.electronicsforu.com/electronicsforu/Lab/freecircuitslist.asp?id=261">Shortwave Transmitter</a>: <p><a href="http://w1.859.telia.com/%7Eu85920178/tx/bug.htm">Simple FM Microphone</a>: <p><a href="http://www.designnotes.com/CIRCUITS/fmxmt.htm">Simple FM Transmitter #1</a>: <p><a href="http://www.cpinternet.com/%7Elyle/lftx.htm">Simple Low FER Transmitter</a>: <p><a href="http://www.reconnsworld.com/transmit_simplerf.html">Simple RF Transmitter</a>: <p><a href="http://www.electronicsteacher.com/gbppr.dyndns.org/PROJ/tv_tx.png">Simple T Volt Transmitter #1</a>: <p><a href="http://www.dct.com/%7Emultiplx/PROJ/tv_tx.txt">Simple T Volt Transmitter #2</a>: <p><a href="http://www.uoguelph.ca/%7Eantoon/circ/rft1.htm">Simplest RF Transmitter</a>: <p><a href="http://www.reed-electronics.com/ednmag/index.asp?layout=article&articleId=CA289969">Small circuit forms programmable 4 to 20 mtransmitter</a>: 04/17/03 EDN-Design Ideas / One of the key challenges in the design of 4 to 20-mA current transmitters is the voltage-to-current conversion stage. Conventional transmitters use multiple op amps and transistors to perform the conversion function. These approaches have been around for a long time, but they are usually inflexible, have poor power efficiency, and have limited current compliance... <p><a href="http://www.ee.washington.edu/eeca/circuits/transmit.html">Small FM Transmitter #2</a>: <p><a href="http://www.ee.washington.edu/circuit_archive/circuits/transmit.html">Small Radio Transmitter</a>: <p><a href="http://w1.859.telia.com/%7Eu85920178/tx/sparky.htm">Spark gap Transmitter</a>: <p><a href="http://www.zen22142.zen.co.uk/Circuits/rf/bugdetector.htm">Surveillance Transmitter Detector</a>: This circuit can be used to "sweep" an area or room and will indicate if a surveillance device is operative. The problem in making a suitable a detector is to get its sensitivity just right, Too much sensitivity and it will respond to radio broadcasts, too little, and nothing will be heard. <p><a href="http://www.web-ee/Schematics/TV_XMIT/tv_xmit.htm">T Volt Transmitter</a>: allows you to send video to any television in the house, Poptronix kit circuit <p><a href="http://www.e-insite.net/ednmag/contents/images/102899di.pdf">Telephone Transmitter</a>: <p><a href="http://www.aaroncake.net/circuits/3Wfmtran.htm">Three Watt FM Transmitters </a>: <p><a href="http://www.nrgkits.com/workshop/tracking_transmitter_schematic.htm">Tracking Transmitter #1</a>: <p><a href="http://www.reconnsworld.com/transmit_tracker2.html">Tracking Transmitter #2</a>: <p><a href="http://www.reed-electronics.com/ednmag/index.asp?layout=article&articleId=CA244148">Transmitter senses triple relative humidity figures</a>: 09/26/2002 EDN - Design Ideas / The circuit in Figure 1 is a triple, relative-humidity sensor and radio transmitter. Sensors 1 and 2 form two gated oscillators with natural frequencies of 10 and 5 kHz, respectively, at relative humidity of 50%. The gated oscillators use variable resistances R2 and R3, respectively. Together, these two oscillators generate FSK-modulated outputs at output of IC1B, Pin 6.. <p><a href="http://w1.859.telia.com/%7Eu85920178/tx/317-tx.htm">Transmitter using LM317</a>: <p><a href="http://www.zen22142.zen.co.uk/Circuits/rf/2bjttx.htm">Two Transistor FM Transmitters</a>: <p><a href="http://www.electronicsteacher.com/www.alphalink.com.au/_parkerp/2v40.gif">Two Valve 40m CW Transmitter</a>: <p><a href="http://members.tripod.com/%7Epetlibrary/rfmod.htm">VHF / UHF T Volt Modulator</a>: Elektor January1985 <p>VHF Audio Video Transmitter: This circuit is a TV transmitter on VHF band. <p><a href="http://www.electronicsteacher.com/circuitos.tripod.cl/schem/r36.gif">VHF beacon transmitter </a>: <p><a href="http://www.designnotes.com/CIRCUITS/fmtransmitter.htm">VHF FM Transmitter</a>: <p><a href="http://www.peg.si/electro/transmiter.html">VHF Transmitter</a>: <p><a href="http://www.ews.uiuc.edu/%7Enshin/PROJECTS/XMITTER/">Video / Audio Wireless Transmitter</a>: circuit diagram and project description <p>Video to RF Modulator: This circuit is a RF modulator which can be used for modeling of video signal. <p><a href="http://www.estss.com/DEMO/HW/XMITTER/">Video/Audio Wireless Transmitter</a>: <p><a href="http://www.electronicsteacher.com/circuitos.tripod.cl/schem/r111.gif">Wire Tracer</a>: <p><a href="http://www.electronicsteacher.com/circuitos.tripod.cl/schem/r90.gif">Wireless IR headphone Transmitter</a>: <p><a href="http://www.electronicsteacher.com/circuitos.tripod.cl/schem/r112.gif">Wireless Microphone #1</a>: <p><a href="http://www.electronicsteacher.com/circuitos.tripod.cl/schem/r71.gif">Wireless Microphone #2</a>: <p><a href="http://www.designnotes.com/CIRCUITS/mic.htm">Wireless Microphone #3</a>: <p><a href="http://www.electronicsteacher.com/circuitos.tripod.cl/schem/r90.gif">Wireless Microphone Transmitter</a>: <p><a href="http://hawkins.pair.com/wlw500schematic.shtml">WLW 500KW Transmitter Schematic</a>: <p><a href="http://www.electronicsteacher.com/circuitos.tripod.cl/schem/r36.gif">XTAL Locked tone Transmitter</a>: </p> Unknownnoreply@blogger.com1tag:blogger.com,1999:blog-1468278518116080443.post-36309661848591689342014-07-04T03:53:00.001-07:002014-07-04T03:55:51.043-07:00detailsUSB FM Transmitter Circuit for PC and Laptop<h5> </h5> <p align="justify"> <p align="justify"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiN2rm1GLI0_wLxY6k7pT5TocFXB1GWQn1zTT8fRbf4a0WZTmBWJmIisiqJK4hCWajUtPDu7u8Ekb5YxrAcp4loMlwbkFgCrSTS8tWl9jAdN_nqzYrQoKrzzswywOzO5TCTdhwpO4UU98s/s1600/USB_FM_Transmitter_Prototype.jpg"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiN2rm1GLI0_wLxY6k7pT5TocFXB1GWQn1zTT8fRbf4a0WZTmBWJmIisiqJK4hCWajUtPDu7u8Ekb5YxrAcp4loMlwbkFgCrSTS8tWl9jAdN_nqzYrQoKrzzswywOzO5TCTdhwpO4UU98s/s1600/USB_FM_Transmitter_Prototype.jpg"> </a></p> <p align="justify">Here's a small FM transmitter ciruit for your desktop or laptop to enjoy the movie and music from a distance. This FM transmitter, which is powered by USB, recovers output on your computer or your MP3 player to the relay on the tape FM (frequency 108 MHz). For Assemblying this FM transmitter kit, an electronics hobbyist will have built in about 30 minutes.<br><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgudz6qMVZMfIarGL86NZYq58jiqSuQVR-lhObiWYS7OqtaJGOaglsT1N4jEfwdFq1djNdblMrlhXDzlqj57jl_gA_kBD7O5nXhMEIKpZeFvZr9a3es_GP6qj3TdKIB3XspkhicQUrdHSM/s1600/USB_FM_Transmitter.jpg"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgudz6qMVZMfIarGL86NZYq58jiqSuQVR-lhObiWYS7OqtaJGOaglsT1N4jEfwdFq1djNdblMrlhXDzlqj57jl_gA_kBD7O5nXhMEIKpZeFvZr9a3es_GP6qj3TdKIB3XspkhicQUrdHSM/s320/USB_FM_Transmitter.jpg" width="320" height="195"></a></p> <p align="justify"><a name="more"></a> <p align="justify"><b>FM Transmitter Construction</b><br>It is not necessary to drill the transmitter PCB. All components will be soldered to the plate with their legs folded. </p> <p align="justify"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiBWC5-65StHHApNS4BLz8QcVXue4lkr4Ikle8-5utRs6V-6Dqbr8BfGUeBT_S5ZuR7N7CXpoU_EXCe6rvxD4YmUKOXbvEXG-bMv3UQZtj8ShknKUVUA4xBgdYFP7UnVZYkoK-517x7U1s/s1600/USB_Mini_FM_Transmitter_Circuit_Schematic.jpg"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiBWC5-65StHHApNS4BLz8QcVXue4lkr4Ikle8-5utRs6V-6Dqbr8BfGUeBT_S5ZuR7N7CXpoU_EXCe6rvxD4YmUKOXbvEXG-bMv3UQZtj8ShknKUVUA4xBgdYFP7UnVZYkoK-517x7U1s/s320/USB_Mini_FM_Transmitter_Circuit_Schematic.jpg" width="320" height="187"></a></p> <p align="justify"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFKPAjHnSgJfazy7hCXPxz58yeJXBpYfSPh2SyNNxCuC-6qj_uG9jwBhT7OnHjsvm0erH71e71eddMu5Z0WKHlGZPhpU9FL_038TdNTChIkr1UnKfXuUcoFs5j0yf646KUkdsqPfvCrqs/s1600/USB_Mini_FM_Transmitter_Circuit_Board.jpg"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgFKPAjHnSgJfazy7hCXPxz58yeJXBpYfSPh2SyNNxCuC-6qj_uG9jwBhT7OnHjsvm0erH71e71eddMu5Z0WKHlGZPhpU9FL_038TdNTChIkr1UnKfXuUcoFs5j0yf646KUkdsqPfvCrqs/s200/USB_Mini_FM_Transmitter_Circuit_Board.jpg" width="200" height="141"></a><br>The two transistors and the LEDs are polarized:<br>The transistor has a flat side, the LED a foot longer than the other is the anode (A), the other is the cathode (K). The audio cable (minijack) must be transformed from a stereo cable into a cable.<br>Mono Sound:<br>Soldering together the white and red cables, leaving aside the yellow cable (mass). The frequency setting will be turning the variable capacitor gently with a screwdriver or thin cardboard but rigid.</p> <p align="justify"> <p align="justify"><b>FM Transmitter Parts List</b><br>* 1 Ohm resistor 510 (green - brown - brown)<br>* 100 resistor 1 kOhm (brown - black - yellow)<br>* 1 MOhm resistors (brown - black - green)<br>* 1 capacitor 0.1 uF (0.1)<br>* 1 nF capacitor 47 (0.047)<br>* 1 capacitor 4.7 pF (479)<br>* 2 pF capacitors 22 (22)<br>* 1 variable capacitor 1.5 pF ... 15<br>* 2 transistor BF 246 (F246A)<br>* 1 red LED<br>* 1 audio cable (minijack) </p> <p align="justify"><a name="more"></a> Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-1468278518116080443.post-69905099123834286142014-07-02T18:08:00.001-07:002014-07-02T18:08:08.987-07:00The Complete FM Bug<p align="justify"> </p> <p align="justify"> <p align="justify"><img border="0" src="http://www.talkingelectronics.com/projects/FM-Bug/FM-Bug.gif" width="510" height="262"><br><b>FM BUG Circuit</b></p> <p align="justify">Corporate espionage is reaching new heights in sophistication. The latest information to be released shows the depths firms will go to pry into a rival firm's operations.<br>By using the latest in electronic bugging, they have stolen information, secrets and even formulas known only to the inventors themselves.<br>Take the example of one firm:Leaks from Top Management level remained a mystery until, one day, a bug was discovered inside the Managing Director's office.Sitting prominently on his desk was a gift box of imported cigars!Cleverly concealed in the lower part of the box was a miniature FM transmitter . . all a gift from a phony sales rep.This is just one of the many bugging devices available on the eaves-dropping market. The range includes pen and pencil holders, trophies, framed pictures and office furniture with false bottom drawers.<br>These products are readily sold to fledgling companies, eager to nestle into big brother's market.<br>And for a while these bugging devices worked. Few firms knew of their existence, and even less on how to sniff them out.<br>But that has all changed now. If a corporation suspects a leak at any level, the first thing they order is an investigation into security. Not only personnel, but information and electronic security.<br>Debugging has grown into big business. Most large security organisations have a section concentrating on electronic surveillance including bugging and debugging.<br>They use scanners to detect hidden devices and can locate absolutely anything, anywhere, and on any frequency.<br>It was only after the firm above had commissioned a scan of the entire floor, that the cigar box was discovered. Its innocence had deceived everyone. And cost them a small fortune!<br>Bugging of this kind is completely illegal and we don't subscribe to this type of application at all.<br>But the uses for our SUPER-SNOOP FM WIRELESS MICROPHONE can be harmless, helpful and a lot of fun.<br>Our unit is both compact and very sensitive and can be used to pick up even the faintest of conversations or noises and transmit them 20 or so metres to any FM receiver.<br>When you build the FM BUG you will see why we consider the design to be very clever. We have used only low priced components and they are all easy to obtain.<br>No air trimmer capacitor is required as the coil is squeezed slightly to obtain the desired frequency. This has allowed us to fit the bug into a tooth-brush case so that it can be carried around or placed on a shelf.<br>If it is set between two books it will be hidden from view or as a supervision accessory it can be placed on a small child, etc. The transmitted signal will over-ride the background noise and the output will be clean. If the child wanders beyond the range of the transmitter, the background noise will come up and signal that the tot is out of range.<br>As an added bonus, you can listen to the chatterings and squabbles as the children amuse themselves in the back yard.<br>It is also great for picking up the first signs of a child awakening from his afternoon sleep or it can be used as an indicator from a bed-ridden patient.<br>The great advantage of the bug is the absence of wires. And since it draws only about 5-10 milliamps, the pair of AAA cells will last for many months.<br>The success of this FM BUG is the use of TWO transistors in the circuit. To create a good design, like this, each transistor should be required to perform only one task. In any type of transmitter, there is a minimum of two tasks.<br>One is to amplify the signal from the microphone and the other is to provide a high frequency oscillator.<br>The amplified microphone signal is injected into the oscillator to modify its frequency and thus produce a FREQUENCY MODULATED oscillator. If an aerial is connected to the output of the oscillator, some of the energy will be radiated into the atmosphere.<br>To increase the output of our design, an RF amplifier would be needed but this gets into legal technicalities with maximum transmitting power.<br>It may be of Interest to know that a record distance of 310 miles was achieved with a 350 micro-watt transmitter in the USA, some 15 years ago. This equates to an astounding ONE MILLION miles per watt!<br>In simple terms, an RF amplifier becomes a LINEAR amplifier.<br>We have opted for sensitivity and the first transistor is employed as a pre-amplifier. This will enable you to pick up very low-level sounds and transmit them about 20 to 50 metres.<br><b>MAKING THE OSCILLATOR COIL</b><br>The only critical component in the FM BUG is the oscillator coil. When I say critical, I am referring to its effect on the frequency. Its critical nature only means it must not be touched when the transmitter is in operation as this will detune the circuit completely.<br>It is the only component which needs to be adjusted or aligned and we will cover its winding and formation in detail.<br>The oscillator coil is made out of tinned copper wire and does not need any insulation. This is not normal practice but since the coil is small and rigid, the turns are unable to touch each other and short-out.<br>The coil is made by winding the tinned copper wire over a medium-size Philips screw-driver. The gauge of wire, the diameter of the coil and the spacing between turns is not extremely important and it will be adjusted in the alignment stage. However when the project is fully aligned, it must not be touched at all.<br>Don't be over-worried at this stage. Just follow the size and shape as shown in the diagram and everything will come out right in the end.</p> <p align="justify"><img border="0" src="http://www.talkingelectronics.com/projects/FM-Bug/Coil.gif" width="270" height="150"></p> <p align="justify"><b>THE DETAILS:</b><br>The coil has 5 turns and is wound on a 3.5mm shaft. To be more specific, it has 5 loops of wire at the top and each end terminates at the PC board. The coil must be wound in a clock-wise direction to fit onto the board and if you make a mistake, rewind the coil in the opposite direction.<br><b>CONSTRUCTION</b><br>Construction is quite straight-forward as everything is mounted on the printed circuit board. The only point to watch is the height of some of the components. The electrolytic must be folded over so that the board will fit into the case.<br>Positioning of the parts is not as critical as you think as the final frequency is adjusted by squeezing the coil together or stretching it apart.<br>However it is important to keep the component leads as short as possible and the soldering neat due to the high frequencies involved. The components must be soldered firmly to the board so that they do not move when the transmitter is being carried.<br>Even the poorest of soldering will work but who wants to see poor soldering on a project?<br>The soldering may not affect the resulting frequency but poor layout of the components certainly will.<br>All the resistors must be pressed firmly against the PC board before soldering and the two transistors must be pushed so that they are as closes as possible to the board.<br>Some BC 547 transistors will not work in the circuit. Maybe the frequency is too high. SGS BC 547 transistors did not work at all. The other two types: f BC 547 and Philips BC 547 worked perfectly.<br>All the small-value capacitors are ceramic as they are not critical in value and do not need to be high stability. But you must be careful when identifying them. It would be a very simple mistake to buy a 56p instead of 5p6 because there is no difference in the size. 22n may be identified with 223 or 22n or .022. A capacitor marked 22k will be a 22p cap and will not be suitable. The 1n capacitor may be marked 1n or .001 or 102. These are all the same value. The value 101 or 103 is NOT 1n so be careful, the caps may be about the same size. The rule is: don't use a capacitor unless its markings are clear and you are sure of the value.</p> <p align="justify"><img border="0" src="http://www.talkingelectronics.com/projects/FM-Bug/FB-Bug-5.jpg" width="471" height="151"><br><b>The complete FM BUG</b></p> <p align="justify">The switch is mounted on the PC board with its three terminals fitted into the large holes.<br>The final items to add to the board are the two AAA cells. These come with the kit and we have chosen them for slenderness so that they can be fitted side-by-side.<br>It is very difficult to solder to the zinc case but if you roughen the surface with a file and use a large, HOT, soldering iron, the job can be done very quickly. Use a piece of tinned copper wire to join the positive of one to the negative of the other. At the other end, solder longer lengths of wire so that they can be connected directly to the PC board. Make sure the positive terminal connects to the plus on the PC board.</p> <p align="justify"><img border="0" src="http://www.talkingelectronics.com/projects/FM-Bug/FB-Bug-6.jpg" width="417" height="299"><br><b>Top and bottom of the FM BUG PC board</b></p> <p align="justify">AAA cells are also obtainable at photographic shops. The only alternative is an 'N' cell which is nearly as thin as an AAA cell but only half the length.<br>The terminal marked A on the board is the antenna output. For a frequency of 90MHz, the antenna should be 165cm long. This is classified as a half-wave antenna and provides one of the most effective radiators. If you find the antenna gets in the way you can opt for a quarter-wave antenna and this will be 83cm long. If you only require to transmit 10 to 20 metres the antenna can be as short as 42cm or even as low as 5 or 10 cm.<br>The most suitable length will depend on the sensitivity of the FM radio used to pick up the signal and the obstructions between the transmitter and receiver. It will be a good experiment for you to 'cut' your own antenna and determine which is the most suitable for your application.<br><b>HOW THE CIRCUIT WORKS</b><br>The circuit consists of two separate stages. The first is an audio pre-amplifier and the second is a 90MHz oscillator.<br>The first stage is very simple to explain. It is a self-biasing common-emitter amplifier capable of amplifying minute signals picked up by the electret microphone. It delivers these to the oscillator stage. The amplification of the first stage is about 70 and it only operates at audio frequencies. The 22n capacitor isolates the microphone from the base voltage of the transistor and allows only AC signals to pass through. The transistor is automatically biased via the 1M resistor which is fed from the voltage appearing at the collector. This is a simple yet very effective circuit. The output from the transistor passes through a 2.2u electrolytic. This value is not critical as its sole purpose is to couple the two stages.<br>The 47k, 1n, 470R and 22n components are not critical either. So, what are the critical components in this circuit?<br>The critical components are the coil and 47p capacitor. These determine the frequency at which the bug will transmit. In addition, the effective capacitance of the transistor plays a deciding factor in the resulting frequency.<br>This stage is basically a free-running 90MHz oscillator in which the feedback path is the 5p6 capacitor.<br>When the circuit is turned on, a pulse of electricity passes through the collector-emitter circuit and this also includes the parallel tuned circuit made up of the oscillator coil and the 47p capacitor. This pulse of electricity is due to the transistor being turned on via the 47k resistor in the base circuit.<br>When ever energy is injected into a tuned circuit, the energy is firstly absorbed by the capacitor. The electricity will then flow out to the coil where it is converted to magnetic flux. The magnetic flux will cut the turns of wire in the coil and produce current and voltage which will be passed to the capacitor.<br>In theory, this current will flow back and forth indefinitely, however in practice, there are a number of losses which will cause the oscillations to die down fairly quickly.<br>If a feedback circuit is provided for the stage, the natural RESONANT frequency of the coil/capacitor combination will be maintained. The 5p6 provides this feedback path and keeps the transistor oscillating.<br>The 5p6 feeds a small sample of the voltage appearing at the collector, to the emitter and modifies the emitter voltage. The transistor sees its base-to-emitter voltage altering in harmony with the resonant frequency of the tuned circuit and turns the collector on and off at the same frequency.<br>Thus there is a degree of stability in the oscillator frequency.<br>The actual frequency of the stage is dependent upon the total capacitance of the circuit and this includes all the other components to a minor extent.<br>Once the basic frequency of 90MHz is set, the variations in frequency are produced by the changes in effective capacitance of the transistor. This occurs when its base voltage is increased and reduced. The electret microphone picks up the sound waves which are amplified by the first transistor and the resulting frequency is passed to the base of Q2 via the 2.2u electrolytic.<br>This alters the gain of the transistor and changes its internal capacitance. This junction capacitance modifies the oscillator with a frequency equal to the sound entering the microphone thus FREQUENCY MODULATING the circuit. A short length of antenna wire is connected to the collector of the oscillator via a coupling capacitor and some of the energy of the circuit will be radiated to the surroundings.<br>Any FM receiver will pick up this energy and decode the audio portion of the signal.<br><b>SETTING UP THE TRANSMITTER</b><br>When the FM BUG is complete, checked and ready for insertion into its case, there is one slight adjustment which must be made to align it to the correct frequency.<br>As we have said, the only critical component is the oscillator coil. It is the only item which is adjustable.<br>Since we are working with a very high frequency, the proximity of your hand or even a metal screw-driver will tend to de-tune the oscillator appreciably.<br>For this reason you must use a plastic aligning stick to make the adjustment. Any piece of plastic will do. A knitting needle, pen barrel or plastic stirring stick can be used.<br>Place the bug about a metre from the FM radio and switch both units on. Tune the radio to an unused portion of the band and use the alignment stick to push the turns of the coil together. Make sure none of the turns touch each other as this will short out the operation of the oscillator.<br>All of a sudden you will hear the background noise diminish and you may even get feed back. This amount of adjustment is sufficient. Place the BUG in its case and tape up the two halves.<br>The fine tuning between radio and transmitter is done on the radio. Peak the reception and move the BUG further away. Peak the fine tune again and move the BUG into another part of the house and see how far it will transmit.<br><b>IF THE BUG FAILS</b><br>If the bug fails to operate, you have a problem. Simple digital tests will not fix it nor will ordinary audio procedures. The frequency at which the BUG operates is too high.<br>You have to use a new method called comparison.<br>This involves the comparing of a unit which works, with the faulty unit.<br>This means it is ideal for a group of constructors to build a number of units and compare one against the other.<br>This will not be possible with individual constructors and they will have to adapt this fault-finding section.<br>The first fact you have to establish is the correct operation of the FM receiver.<br>If you have another BUG and it is capable of transmitting through the radio you know the radio is tuned to the correct frequency. Otherwise you will have to double-check the tuning of the dial and make sure the radio is switched to the correct setting.<br>The next stage is to determine if the BUG is functioning AT ALL. The only voltage measurements you can make are across the collector-emitter terminals of the first transistor (1 v to 1.5v) and across the collector-emitter terminals of the second transistor (1.3v to 1.5v) These values won't tell you much, except that the battery voltage is reaching the component.<br>Tune the radio to about 90MHz and lay the radio antenna very close to the antenna of the BUG. Switch the BUG on and off via the slide switch. You should hear a click in the radio if the BUG is on a frequency NEAR 90MHz. Move the turns of the aerial coil together or apart with a plastic stick as you switch the unit ON and OFF.<br>If a click is heard but no feed-back, the oscillator will be operating but not the pre-amp stage. This could be due to the electret microphone being around the wrong way, the transistor around the wrong way, a missing component or an open 2.2u electro.<br>If the fault cannot be located, compare your unit with a friend's. You may have made a solder bridge, connected the batteries around the wrong way, made the coil too big or used the wrong value capacitor for one of the values.<br>If all this fails, put the unit aside and start again.</p> <p align="justify"><strong>PARTS LIST</strong><br>1 - 470R<br>1 - 10k<br>1 - 22k<br>1 - 47k<br>1 - 1M<br>1 - 5.6p ceramic = 5p6<br>1 - 22p ceramic or 27p or 33p<br>1 - 47p ceramic<br>1 - 1n ceramic = 1,000p or 102<br>1 - 22n ceramic = .022 or 223<br>1 - 2.2u 16v or 25v<br>2 - BC 547 transistors<br>1 - mini slide switch spdt.<br>1 - electret microphone (insert)<br>2 - AAA cells<br>10cm tinned copper wire<br>2 - metres aerial wire<br><b>1 - FM BUG PC board</b></p> Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-1468278518116080443.post-1789217616927467212014-06-28T19:21:00.001-07:002014-06-28T19:21:49.933-07:00FM Transmitter<p><img src="http://www3.telus.net/chemelec/Projects/Xmitter/Xmitter-1.png" width="537" height="410"></p> Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-1468278518116080443.post-66906519088650601212014-06-28T09:31:00.001-07:002014-06-28T09:31:49.203-07:00Single transistor Miniature FM transmitter with VCO<h3 align="justify"> </h3> <p align="justify">This simple transmitter allows you to broadcast on FM radio band (VHF) 87.5 - 108 MHz. It consists of a simple oscillator with silicon planar RF PNP transistor. Directly to the oscillator an antenna is connected. Due to the large amplitude of RF voltage is sufficient antenna length of about 5-10 cm. I used insulated 7cm long copper wire 1mm diameter. I eliminated the tuning capacitor, which is usual for most bugs and miniature transmitters, because this greatly complicates the tuning. From my own experience I know that if you get closer to such capacitor, the operating frequency is changed. That's why I chose to use the voltage tuning using the Voltage Controlled Oscillator (VCO). Instead of tuning capacitor the varicap (capacitance diode) is used, which changes its capacity by changing the reverse DC voltage. We can tune the operating frequency by changing the DC voltage using the trimmer P1. Varicap also provides frequency modulation.</p> <p align="justify"><b>Tuning:</b> Set P1 to the center. Turn on the FM radio and tune it to an unoccupied frequency in the 87.5 - 108 MHz band. You will hear a noise. Turn on the transmitter and the first tune the operating frequency of roughly by stretching turns in the coil L1. Then fine-tune the frequency using P1. Proper tuning is indicated by the radio getting silent. You can then connect audio source to the input (such as cassette player, CD or MP3 player, record player, audio output of PC or laptop, etc.). It is also possible to tune while already connected to the signal source. The circuit can be powered from 5V USB port available on your PC or laptop.</p> <p align="justify"><br> Inductor L1 is airborne and has six turns of 0.5 mm diameter wire wound on 3 mm diameter. Varicap is arbitrary, which covers the range of about 5-20pF, such as BB105, KB105, KB109. I used the varicap KB109G made by Tesla with yellow paint on the cathode. The transistor is a high-frequency planar PNP type, for example, BF970, BF979, or simmilar. You can also use a transistor with different type of case. The disadvantage of the circuit is sensitivy to changes in supply voltage (it is changing the varicap voltage and thus the operating frequency). The antenna is connected directly to the oscillator, so if you touch it or placing it near the conductive object, the frequency shifts. At its simplicity, however, the circuit works surprisingly well and the range is about 20 to 100 meters. You can use power supply of 5-12V or a battery. There should be no ripple in the supply voltage, otherwise it may be heard in the receiver.</p> <p align="justify"> Warning: Broadcasting on VHF-FM band may be illegal in your country. Author does not take any responsibility for your possible legal penalties for illegal broadcast or due to abuse of the bug for illegal purposes! Everything you do at your own risk. <p align="justify"><img alt="" src="http://danyk.cz/sten3.png" width="490" height="310"><br>The schematic of the Single transistor Miniature FM transmitter with VCO</p> Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-1468278518116080443.post-73333586955000428812014-06-28T09:30:00.001-07:002014-06-28T09:30:03.406-07:0088-108 MHz FM covert listening device (bug)<h3> </h3> <p align="justify"> This is a simple listening bug. The signal can be tuned on any FM radio. The first transistor (in the circuit diagram on the left) works as an oscillator (in Colpitts connection), the frequency depends on: trimmer capacitor, inductor (with 4 turns wound on 5mm diameter, no core), varicap and capacitor between collector and emitter of the first transistor. Low frequency signal from the electret microphone affects varicap voltage and thus its capacity. Varicap affectc the oscillator frequency and thus modulates the carrier wave. The second transistor acts as an amplifier and also contributes to separation of the antenna from the oscillator, thereby improving the frequency stability.</p> <p align="justify"><br> How to use the bug: Turn on the FM radio and connect the bug to voltage 9-12 VDC and try to tune the radio frequency bugs. If the bug is near the radio and the radio is well tuned, you can hear feedback whistling. Range of this bug is about 20 to 100m (66 to 330 feet). The antenna is cca 10 - 30cm (1/3 - 1 feet) wire.</p> <p align="justify"> Warning: Broadcasting on VHF-FM band may be illegal in your country. Author does not take any responsibility for your possible legal penalties for illegal broadcast or due to abuse of the bug for illegal purposes! Everything you do at your own risk. <p align="justify"><img alt="" src="http://danyk.cz/stenice.gif" width="549" height="277"></p> Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-1468278518116080443.post-50491275862605669062014-06-28T09:25:00.001-07:002014-06-28T09:25:19.928-07:005W1.5W 88-108Mhz FM Transmitter 14MHz (20m) AM Transmitter<h3> </h3> <h3> </h3> <h3> </h3> <p align="justify"> This transmitter is designed to transmit sound (music, speech, ...) at frequencies 88-108MHz with a frequency modulation (FM). Its RF power is about 1.5 W. The first transistor is used as an RF oscillator. Varicap allows the oscillator frequency shifting and thus its frequency modulation and frequency tuning via potentiometer. Varicap may not be the BB105, it can be BB409, BB109G, KB109G or other type. The second transistor is the power output stage. The output signal goes through a filter to remove harmonics and then it enters antenna, eg dipole or Yagi antenna (it has better directivity). Power transistor is on the heatsink with min. 100 cm2 area. Coils are air, wire diameter of 0.6 mm wound on 5 mm. <p align="justify"> Warning! Operating this transmitter without permission is illegal. <p align="justify"><img alt="" src="http://danyk.cz/vysilac.gif" width="551" height="282"><br>1.5W 88-108Mhz FM power Transmitter schematic (note: "z" means number of turns)</p> Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-1468278518116080443.post-14542489447807960512014-06-21T23:39:00.001-07:002014-06-21T23:39:48.940-07:00Simple FM Receiver<p align="justify"> <h6> </h6> <h6> </h6> <p align="justify">Frequency modulation is used in radio broadcast in the 88-108MHz VHF band. This bandwidth range is marked as FM on the band scales of radio receivers, and the devices that are able to receive such signals are called FM receivers. The FM radio transmitter has a 200kHz wide channel. The maximum audio frequency transmitted in FM is 15 kHz as compared to 4.5 kHz in AM. This allows much larger range of frequencies to be transferred in FM and thus the quality of FM transmission is significantly higher than of AM transmission.</p> <p align="justify"><br>Here’s a simple FM receiver with minimum components for local FM reception. Transistor BF495 (T2), together with a 10k resistor (R1), coil L, 22pF variable capacitor (VC), and internal capacitances of transistor BF494 (T1), comprises the Colpitts oscillator. The resonance frequency of this oscillator is set by trimmer VC to the frequency of the transmitting station that we wish to listen. That is, it has to be tuned between 88 and 108 MHz. The information signal used in the transmitter to perform the modulation is extracted on resistor R1 and fed to the audio amplifier over a 220nF coupling capacitor (C1).</p> <p align="justify"><img border="0" hspace="3" vspace="3" src="http://www.electronicsforu.com/electronicsforu/circuitarchives/my_documents/my_pictures/F61_1.jpg" width="531" height="230"></p> <p align="justify">You should be able to change the capacitance of the variable capacitor from a couple of picofarads to about 20 pF. So, a 22pF trimmer is a good choice to be used as VC in the circuit. It is readily available in the market. If you are using some other capacitor that has a larger capacitance and are unable to receive the full FM bandwidth (88-108 MHz), try changing the value of VC. Its capacitance is to be determined experimentally.</p> <p align="justify">The self-supporting coil L has four turns of 22 SWG enamelled copper wire, with air core having 4mm internal diameter. It can be constructed on any cylindrical object, such as pencil or pen, having a diameter of 4 mm. When the required number of turns of the coil has reached, the coil is taken off the cylinder and stretched a little so that the turns don’t touch each other.</p> <p align="justify">Capacitors C3 (100nF) and C10 (100µF, 25V), together with R3 (1k), comprise a band-pass filter for very low frequencies, which is used to separate the low-frequency signal from the high-frequency signal in the receiver.You can use the telescopic antenna of any unused device. A good reception can also be obtained with a piece of isolated copper wire about 60 cm long. The optimum length of copper wire can be found experimentally.</p> <p align="justify">The performance of this tiny receiver depends on several factors such as quality and turns of coil L, aerial type, and distance from FM transmitter. IC LM386 is an audio power amplifier designed for use in low-voltage consumer applications. It provides 1 to 2 watts, which is enough to drive any small-size speaker. The 22k volume control (VR) is a logarithmic potentiometer that is connected to pin 3 and the amplified output is obtained at pin 5 of IC LM386. The receiver can be operated off a 6V-9V battery.</p> Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-1468278518116080443.post-68769133803703975882014-06-21T18:22:00.001-07:002014-06-21T18:22:32.835-07:00VHF FM Transmitter MAX2606<p> <p><a href="http://circuit-zone.com/ediy_blog/616/vhf-fm-transmitter-max2606.jpg"><img border="0" alt="VHF FM Transmitter MAX2606" src="http://circuit-zone.com/ediy_blog/616/vhf-fm-transmitter-max2606.jpg" width="500" height="366"></a> <p align="justify">If you want to be independent of the local radio stations for testing VHF receivers, you need a frequency-modulated oscillator that covers the range of 89.5 to 108 MHz — but building such an oscillator using discrete components is not that easy. Maxim now has available a series of five integrated oscillator building blocks in the MAX260x series which cover the frequency range between 45 and 650 MHz. The only other thing you need is a suitable external coil, dimensioned for the midrange frequency. Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-1468278518116080443.post-80647646551270751622014-06-21T18:20:00.001-07:002014-06-21T18:20:38.074-07:00Stereo FM Transmitter with BA1404<p> <p> <p><a href="http://circuit-zone.com/ediy_blog/635/stereo-fm-transmitter-ba1404.jpg"><img border="0" alt="Stereo FM Transmitter with BA1404" src="http://circuit-zone.com/ediy_blog/635/stereo-fm-transmitter-ba1404.jpg" width="484" height="221"></a> <p align="justify">A high quality stereo FM transmitter circuit is shown here. The circuit is based on the IC BA1404 from ROHM Semiconductors. BA1404 is a monolithic FM stereo modulator that has built in stereo modulator, FM modulator and RF amplifier. The FM modulator can be operated from 76 to 108MHz and power supply for the circuit can be anything between 1.25 to 3 volts. In the circuit R7, C16, C14 and R6, C15, C13 forms the pre-emphasis network for the right and left channels respectively. This is done for matching the frequency response of the FM transmitter with the FM receiver. Inductor L1 and capacitor C5 is used to set the oscillator frequency. Network C9,C10, R4,R5 improves the channel separation. 38kHz crystal X1 is connected between pins 5 and 6 of the IC. Composite stereo signal is created by the stereo modulator circuit using the 38kHz quartz controlled frequency. Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-1468278518116080443.post-80440278122460253562014-06-21T18:19:00.001-07:002014-06-21T18:19:06.812-07:00FM Transmitter with 2N2218<p> <p> <p align="justify"><a href="http://circuit-zone.com/ediy_blog/642/fm-transmitter-with-2n2218-schematic.gif"><img border="0" alt="FM Transmitter with 2N2218" src="http://circuit-zone.com/ediy_blog/642/fm-transmitter-with-2n2218-schematic.gif" width="455" height="312"></a></p> <p align="justify">Here's simple FM transmitter circuit using medium power 2N2218 transistor. Micropohone is of electret type that connects to two input terminals and the antenna should be a copper wire from 15 to 40 cm. Below is schematic circuit of the fm transmitter. Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-1468278518116080443.post-48748094855343659352014-06-21T18:17:00.001-07:002014-06-21T18:17:48.104-07:00Phone Spy Transmitter<p> <p><a href="http://circuit-zone.com/ediy_blog/653/phone-spy-transmitter.jpg"><img border="0" alt="Phone Spy Transmitter" src="http://circuit-zone.com/ediy_blog/653/phone-spy-transmitter.jpg" width="475" height="211"></a> <p align="justify">Here is a very simple telephone broadcaster transmitter which can be used to eavesdrop on a telephone conversation. The circuit can also be used as a wireless telephone amplifier. One important feature of this phone transmitter is that the circuit derives its power directly from the active telephone lines, and thus avoids use of any external battery or other power supplies. Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-1468278518116080443.post-76200033533339036272014-06-21T18:16:00.001-07:002014-06-21T18:16:21.848-07:001.5V FM Transmitter<p> <p><a href="http://circuit-zone.com/ediy_blog/658/1.5v-fm-broadcast-transmitter.jpg"><img border="0" alt="1.5V FM Broadcast Transmitter" src="http://circuit-zone.com/ediy_blog/658/1.5v-fm-broadcast-transmitter.jpg" width="442" height="289"></a> <p align="justify">The objective of this 1.5V FM Broadcast Transmitter design is to provide a simple low-power transmitter solution for broadcasting audio from various audio sources. This transmitter accepts stereo input via two 470K resistors. Since there is no audio level control on the input, the audio level out from the source needs to be adjusted. Or, you can just add a 10k as an input level control. Transmitter's frequency, as built is tunable via spreading or compressing the coil to the desired frequency, and the coil can be glued down. If you want to make one that's tunable, it might be easiest to reduce the 18 pf capacitor and put a small trimmer capacitor in parallel with the inductor (across the reduced value capacitor). Voltage variable capacitors would be an nice alternative to a mechanical variable capacitor but they don't offer much tuning range with only a 1.5V power supply. Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-1468278518116080443.post-82554617187971768832014-06-21T18:14:00.001-07:002014-06-21T18:14:40.843-07:00Coil less FM Transmitter<p> <p><a href="http://circuit-zone.com/ediy_blog/665/coilless-fm-transmitter.gif"><img border="0" alt="Coilless FM Transmitter" src="http://circuit-zone.com/ediy_blog/665/coilless-fm-transmitter.gif" width="451" height="261"></a> <p align="justify">The RF oscillator using the inverter N2 and 10.7Mhz ceramic filter is driving the parallel combination of N4 to N6 through N3.Since these inverters are in parallel the output impedance will be low so that it can directly drive an aerial of 1/4th wavelength. Since the output of N4-N6 is square wave there will be a lot of harmonics in it. The 9th harmonics of 10.7Mhz (96.3Mhz) will hence be at the center of the FM band. N1 is working as an audio amplifier. The audio signals from the microphone are amplified and fed to the varicap diode. The signal varies the capacitance of the varicap and hence varies the oscillator frequency which produce Frequency Modulation. Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-1468278518116080443.post-13938905871352202052014-06-21T18:11:00.001-07:002014-06-21T18:11:59.614-07:001W Long Range FM Transmitter<p> <a href="http://circuit-zone.com/ediy_blog/708/1w-long-range-fm-transmitter.jpg"><img border="0" alt="1W Long Range FM Transmitter" src="http://circuit-zone.com/ediy_blog/708/1w-long-range-fm-transmitter.jpg" width="555" height="196"></a> <p align="justify">Long range, very stable, harmonic free, FM transmitter circuit which can be used for FM frequencies between 88 and 108 MHz. With good antenna transmitter can cover 5km range. It has a very stable oscillator because it uses LM7809 voltage regulator which is a 9V stabilized power supply for T1 transistor. Frequency adjustment is achieved by using the 10K linear potentiometer. The output power of this long range RF transmitter is around 1W but can be higher if you use transistors like KT920A, BLX65, BLY81, 2N3553, 2SC1970 or 2SC1971. Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-1468278518116080443.post-59265607461371891722014-06-21T18:06:00.001-07:002014-06-21T18:10:18.321-07:004 Transistor FM Transmitter<p> <p> <p><a href="http://circuit-zone.com/ediy_blog/717/4-transistor-fm-transmitter.gif"><img border="0" alt="4 Transistor FM Transmitter" src="http://circuit-zone.com/ediy_blog/717/4-transistor-fm-transmitter.gif" width="552" height="293"></a> <p align="justify">This circuit provides an FM modulated signal with an output power of around 500mW. The input microphone pre-amp is built around a couple of 2N3904 transistors (Q1/Q2), and audio gain is limited by the 5k preset trim potentiometer. The oscillator is a colpitt stage, frequency of oscillation governed by the tank circuit made from two 5pF ceramic capacitors and the L2 inductor. The output stage operates as a 'Class D' amplifier, no direct bias is applied but the RF signal developed across the 3.9uH inductor is sufficient to drive this stage. The emitter resistor and 1k base resistor prevent instability and thermal runaway in this stage. Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-1468278518116080443.post-65083311753509433102014-06-21T18:04:00.001-07:002014-06-21T18:04:37.898-07:001 Watt FM Transmitter Amplifier<p> <p><a href="http://circuit-zone.com/ediy_blog/744/1-watt-fm-transmitter-amplifier.jpg"><img border="0" alt="1 Watt FM Transmitter Amplifier" src="http://circuit-zone.com/ediy_blog/744/1-watt-fm-transmitter-amplifier.jpg" width="405" height="374"></a> <p align="justify">This is a 1 Watt FM Transmitter amplifier with a good design that can be used to amplify a RF signal in the 88 – 108 MHz band. It is very sensitive if you use good RF power amplifier transistors, trimmers and coils. It has a power amplification factor of 9 to 12 dB (9 to 15 times). At an input power of 0.1W the output will be 1W. You must choose T1 transistor depending on applied voltage. If you have a 12V power supply then use transistors like: 2N4427, KT920A, KT934A, KT904, BLX65, 2SC1970, BLY87. At 18 to 24V power supply you must use transistors like: 2N3866, 2N3553, KT922A, BLY91, BLX92A. You may use 2N2219 at 12V but you will get an output power of 0.4W maximum. Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-1468278518116080443.post-46552342563298730522014-06-21T18:01:00.001-07:002014-06-21T18:01:46.118-07:0018W FM Transmitter<p> <p><a href="http://circuit-zone.com/ediy_blog/736/18w-fm-transmitter.jpg"><img border="0" alt="18W FM Transmitter" src="http://circuit-zone.com/ediy_blog/736/18w-fm-transmitter.jpg" width="498" height="293"></a> <p align="justify">Here's FM transmitter for commercial FM band that provides 18 watts of power. Since the electronic diagram is too large we decided to divide it into two parts. The first part is the actual FM transmitter while the second part is 18W RF amplifier. The circuit should be built on an epoxy printed circuit board with the upper face components reserved for interconnecting tracks and the bottom solder to the ground plane. If powered by 14V and 2.5A transmitter outputs 15W of power, whereas 18V and 3.5A will provide 18W. BB110 variable capacitor connected to the collector of transistor BF199 adjusts the transmission frequency of the circuit. 2K2 potentiometer serves as fine tuning. Once the output frequency is adjusted amplifier variable capacitors must be adjusted for maximum output power one stage at a time. All adjustments must be made with 50 Ohm dummy load connected to the output of transmitter. Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-1468278518116080443.post-73488487685845233352014-06-21T04:32:00.001-07:002014-06-21T04:32:38.904-07:00FM Wireless Transmitter<p> </p> <p><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjE95Io0RdX_3cxYKzri6S52ELld_XFoB-1mgq_sh9XbHNOYpF-zOibHXgFTtlOPT_aUCm1Cmb1AWdLQhMOrxHbmRCCu2LYc1mefoNgHuXQudNhWzbYlBv8LnnGzPqZ8or9BAJQ_euTjCjL/s1600-h/fm%252520mike%25255B4%25255D.png"><img style="background-image: none; border-right-width: 0px; padding-left: 0px; padding-right: 0px; display: inline; border-top-width: 0px; border-bottom-width: 0px; border-left-width: 0px; padding-top: 0px" title="fm mike" border="0" alt="fm mike" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj7oPJykwL3U0Trn3bfV2GbeEMdTT0rXDERVwwofIOoSbaQwc42CMsLvdjvEfisQk_kAV-aBarB__GilGTvgZHE6wF1wbuF4uzC98Spl5nkG71cRuUD-6-GQ21zPalUVv1mCmKFRaVZFkQU/?imgmax=800" width="575" height="454"></a></p> Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-1468278518116080443.post-24590349872090703602014-06-21T04:30:00.001-07:002014-06-21T04:30:37.914-07:00FM Interference Filter<p><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhJCF-GIc_kNm7_PT6uOoKo3aA8T5vTW5N3PHHwBIHXPGvjK5Vc-LFlMcz-6Q7iqwlhSU4Q2CLmn6PgcBB6FT-KdSd2TXC1FSt2dx2Uyrdh2JRX6XOoFQZmubi0FACr3qsYuqCSOnZeomqh/s1600-h/fm%252520filter%25255B4%25255D.png"><img style="background-image: none; border-right-width: 0px; padding-left: 0px; padding-right: 0px; display: inline; border-top-width: 0px; border-bottom-width: 0px; border-left-width: 0px; padding-top: 0px" title="fm filter" border="0" alt="fm filter" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgl6VnTD2mdfSieQcPetRVi6cabjKeRzlLQgIg8AiydJT956n3vJXaCXXseOm8fNJ_NWJ-vvyqycLOE8WO9eHc9IKu1LpsF3UFZc0JptCpk7_c1pTuHiqNjiFmkBP7X_evQ8eGVoRTpX0mx/?imgmax=800" width="582" height="418"></a></p> Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-1468278518116080443.post-30019683167946221082014-06-20T01:59:00.001-07:002014-06-20T01:59:33.612-07:00Single Quad Loop For FM Radio DXing<p align="justify"><strong></strong> </p> <h6>N.S.HARISANKAR – VU3NSH</h6> <p><img alt="FM Antenna" src="http://www.hamradio.in/circuits/images/FMAntenna.gif" width="506" height="682"> <p align="justify">The quad antenna have a gain of 1.4 dB over a dipole and also operate over a relatively wide frequency. Quad antenna dipole to form 1/4 lambda each side makes a square. American Radio Amateur (HAM) Clarence C. Moore, W9LZX developed this system in 1939 for the Missionary Radio Station HCJB at Quito of Ecuadaor (South America). The altitude of the station was over 10,000 feet in Andes. The station was operated in 25 m band SW with TX power of 10 KW. The band width of a single dipole is quite narrow. The quad loop is having high gain and less corona discharges etc. The half lambda folded dipole impedance is 288 Ohms (300 Ohms) and this quad loop is having 125 Ohms feed impedance. Due to low impedance of the quad, there is no need of any matching, for a general FM receiver system. <p align="justify">Connecting a folded dipole (gain : 2.14 dB, 1.45 m long and 300 Ohms) to a FM receiver of 75 Ohms input, without any matching, its efficiency becomes to 65% (VSWR-4) and a 125 Ohms quad at 75 Ohms receiver without matching it will get 95% efficiency (VSWR-1.66) with an extra gain of 1.4 dB over a folded dipole. Due to this 3.54 dB gain from a quad loop there will be a terrific FM Radio reception. Using a split dipole, having 75 Ohms feed impedance, there will be correct match of 75 Ohms FM receiver system. But one of the element will be isolated and it makes static and lightning problems. if we ground the cable braid (shield), the entire quad or foled dipole antenna system get grounded and it avoid the threat from static or lightning effects. <p align="justify">FM Radio allocation in India is from 88 MHz to 108 MHz. So the mid frequency is 98 MHz. The equation for getting the wave length of the conductor is (300 x 0.95) / 98 MHz. i.e. 2.908163 meters. If we divide this value by 4 we can get the Quarter Lambda length. i.e. 72.70 cm, we can take it as 73 cm or 74 cm. Due to skin effect of VHF frequency the element should be a tube having more than 4 mm dia or use 3/8th tube for getting good efficiency. <p align="justify"><img alt="Connection To Radio" src="http://www.hamradio.in/circuits/images/FMAntenna_Fig2.gif" width="388" height="210"></p> <p align="justify"><i>Connect with proper connector as per your FM Radio. If there is no external antenna input in your Radio, then connect the Ground (Shield) to Battery negative and other line to the telescopic aerial.</i></p> <h5 align="justify">References</h5> <p align="justify">[1] <a href="http://en.wikipedia.org/wiki/quad_antenna">en.wikipedia.org/wiki/quad_antenna</a><br>[2] <a href="http://http://en.wikipedia.org/wiki/HCJB">en.wikipedia.org/wiki/HCJB</a><br>[3] <a href="http://http://www.cubex.com/history.htm">www.cubex.com/history.htm</a></p> Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-1468278518116080443.post-11134233292950467332014-06-20T01:47:00.001-07:002014-06-20T01:47:37.182-07:00FM Radio Rectangle Super Gainer (Moxon Antenna)<p> <p align="justify"> <p>It is not much popular antenna but much old design!! The original name of this antenna is <em>Two Element Driven Arrays</em>. In 1952 Les Moxon published this <em>Genius Design</em> in QST July Issue. It is a rectangular shaped two elements with a closed spacing of 0.18 lambda. The ends of the two element are folded in 90 degree face to face with a critical spacing of each other. This rectangle beam is popular among ham radio operators as Moxon Antenna. Few hams are using it for HF (SW) bands. It is a directional type antenna with a wide angle of 136 degree typical aperture and with a very good band width. (The Radiation pattern is like <em>Kidney</em> shape, and it is the same in reciprocity) . Due to the bend at the ends of each element and due to the critical spacing of each tips it is a capacity loaded, and it yields the wide bandwidth and low SWR levels. It is a low take of angle type of 14 degree or low typically, and it pick ups maximum stations from planes. Therefore I decided to make this antenna in FM Radio band to receive the spectrum of 88 MHz to 108 MHz. <p>One of my SWL Murali (School Teacher), who is a good listener of MW-SW-FM bands, asked to make an antenna which gives directivity, wide angle and very high gain for his own use. For this purpose I converted the basic design to 3 meter BC band radio use. I made this rectangle beam <em>(Moxon)</em> with 3/8 th aluminum tube. For the critical spacing of each element tips, I made hilum insulators as a prototype. The feed point is connected with a simple cable TV connector called F-Connector which is economical and easily available at the local market. <p>While testing, if it is pointing to eastern direction it will pick the signals from East and also it will pick the signal from South East and North East due to its wide angle aperture. More over the beauty of this antenna is the two elements will give 9 dBi + gain. Typically this antenna gives 7 to 14 dBi depending upto the <em>accuracy of the construction</em> and it can be a wide angle of 100 degrees to 136 degrees, the F/B ratio can be 30 dB to 40 dB. This antenna should be mounted at least 1 lambda of the operating frequency above the ground level. i.e., 3 meter (10 ft). For excellent performance, the height should be 25 to 30 ft. and the surrounding clearance should be maximum. Do not test this antenna near to any metallic objects and that will reduce its performance drastically. <p>For receiving FM BC Bands you can connect any good quality and low loss 75 ohms coaxial cable to the driven elements at the middle point of this antenna. No matching is required like balun, gamma, hair pin etc. and therefore no question of matching loss. Refer the following figures for getting specific ideas about the antenna and its construction. A well constructed rectangle beam antenna is equivalent to a four element yagi antenna. <p>In the next part we will reveal some antenna engineering about rectangle beam for 2 metre ham band operation. <p><img alt="FM bc band - mesurements for 100 Mhz" src="http://www.hamradio.in/circuits/images/Moxon/fig1_mesurements.gif" width="400" height="464"><br><strong>Fig. 1. FM bc band - mesurements for 100 Mhz. This measurements are for 3/8 Aluminium tube (9.5 mm OD)</strong> <p><img alt="FM bc band - mesurements for 100 Mhz" src="http://www.hamradio.in/circuits/images/Moxon/fig2_Moxon.gif" width="510" height="408"><br><strong>Fig. 2. Rectangle beam (Moxon) plot</strong></p> Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-1468278518116080443.post-52693754824441508692014-06-19T18:40:00.001-07:002014-06-19T18:40:56.105-07:001.3W VHF RF Amplifier 2SC1970 88-108 MHz<h5 align="justify"> </h5> <ul> <p> <p><img border="0" alt="1.3W VHF RF Amplifier 2SC1970 88-108 MHz" src="http://electronics-diy.com/schematics/816/P2190149.jpg" width="443" height="285"> <p><img src="http://electronics-diy.com/img/osx/right.gif" width="31" height="23"> <p><img border="0" alt="1.3W VHF RF Amplifier 2SC1970 88-108 MHz" src="http://electronics-diy.com/schematics/816/P2190149.jpg" width="443" height="285"> <h3> </h3> <hr align="left" size="1" width="98%" noshade> <p>This RF power amplifier is based on the transistor 2SC1970 and 2N4427. The output power is about 1.3W and the input driving power is 30-50mW. It will still get your RF signal quit far and I advice you to use a good 50 ohm resistor as dummy load. To tune this amplifier you can either use a power meter/wattmeter, SWR unit or you can do using a RF field meter. <p><img border="0" alt="1.3W VHF RF Amplifier 2SC1970 88-108 MHz" src="http://electronics-diy.com/schematics/816/pa_70.gif" width="580" height="380"> <p><strong>RF Amplifier Assembly</strong></p> <p><br>Good grounding is very important in a RF system. I use bottom layer as Ground and I connect it with the top with wires to get a good grounding. Make sure you have some cooling at the transistor. In my case I put the 2SC1970 close to the PCB to handle the heat. With good tuning the transistor shouldn't become hot.</p> <p><br><strong>RF Amplifier Printed Circuit Board</strong></p> <p><br>You can download a pdf file which is the black PCB. The PCB is mirrored because the printed side side should be faced down the board during UV exposure. To the right you will find a pic showing the assembly of all components on the same board.This is how the real board should look when you are going to solder the components. It is a board made for surface mounted components, so the copper is on the top layer. I am sure you can still use hole mounted components as well.<br>Grey area is copper and each component is draw in different colors all to make it easy to identify for you. The scale of the pdf is 1:1 and the picture at right is magnified with 4 times. Click on the pic to enlarge it.</p> <p><br><strong>Low-Pass Filter</strong></p> <p><br>Some of you might want to add a low-pass filter at the output. I have not added any extra low pass filter in my construction because I don't think it is needed. You can easy find several homepages about low pass filter and how to build them.</p> <p><a href="http://electronics-diy.com/schematics/816/pcb1_3.gif"><img title="1.3W VHF RF Amplifier 2SC1970 88-108 MHz" border="0" alt="1.3W VHF RF Amplifier 2SC1970 88-108 MHz" src="http://electronics-diy.com/schematics/816/pcb1_3.gif" width="473" height="314"></a> <hr align="left" size="1" width="98%" noshade> </ul> Unknownnoreply@blogger.com2tag:blogger.com,1999:blog-1468278518116080443.post-72471260540580720502014-06-19T09:16:00.001-07:002014-06-19T09:16:10.060-07:00Homebrewed Off-Center Fed Dipole<h3 align="justify"> </h3> <p align="justify"><a href="http://wiki.radioreference.com/index.php/File:Ocfd.jpg"><img alt="Ocfd.jpg" src="http://wiki.radioreference.com/images/b/b2/Ocfd.jpg" width="294" height="406"></a></p> <p align="justify">Building A Homebrewed Off-Center Fed Dipole Scanner Antenna. <p align="justify">Aluminum/copper tubing construction: <p align="justify">You will need to check the fit of the tubing with the T connector and the caps while you are at the store. One combination that fits nicely is 3/4" copper pipe with 3/4" CPVC fittings (not to be confused with 3/4" PVC fittings which will be too large). The tubing/connector is held in place with 2 stainless steel sheet metal screws for connecting the balun to each element. <p align="justify">Find a "U" bolt to fit your mast. Drill two holes in the support pipe to fit the U bolt.The support pipe is 18" from the "T" to the mast. <p align="justify">Remember, bandwidth increases as diameter of the elements increases. I think, if I remember correctly, at the hardware store, that a few CPVC fittings will fit copper tubing perfectly! <p align="justify">Some say that the 18" element on top mounted works best,Some like the 48" element on top.It does'nt matter,it works the same. <p align="justify">If you use the copper tubing,be sure to paint it with some good,non-conductive paint.I used to paint mine light grey. -Have fun! (Teraycoda) <p align="justify">For an alternate/temporary mounting option, drill a hole in one of the end caps and put in an eye bolt with a nut on the underside of the cap to secure. Be sure to secure this end cap to the copper tubing somehow, perhaps with an additional small stainless sheet metal screw. Be sure that the eye bolt itself doesn't make electrical contact with the tubing. Also, drill a small weep hole in the bottom end cap to allow any moisture to escape that may accumulate inside. Use the eye bolt and some rope to pulley the antenna up high in a tree, or use a hook to hang it somewhere. Give careful consideration to safety and grounding depending on your particular usage scenario. (Qdude) <div align="justify"> <hr> </div> <h4 align="justify">Variation for Off-Center Fed Dipole Using Simple Wire and 75 to 300 ohm TV Balun Transformer </h4> <p align="justify"><a href="http://wiki.radioreference.com/index.php/File:Offset_dipole_scanner_antenna.jpg"><img alt="Offset dipole scanner antenna.jpg" src="http://wiki.radioreference.com/images/c/cf/Offset_dipole_scanner_antenna.jpg" width="502" height="470"></a></p> <p align="justify">Electrically, this version is the same as the one using copper tubing (above) but can be assembled quickly and is quite portable. While not as broadbanded as an OCFD using copper tubing or other metal with a larger diameter, the OCFD made from simple wire turns in great receive performance in all the commonly scanned bands, as reported here on RR in multiple message threads. <p align="justify">The legs/ends of the dipole are simple bell wire and shown here coiled up. Uncoil them and hang them vertically; doesn't matter if the long or short leg is at the top... works the same either way. The wire terminal lugs shown at the end of the legs of the dipole antenna should NOT be connected electrically to the wires - just crimp them on over the wire insulation. They are used as convenient hangers for the antenna, and not meant for electrical connection. Obviously, the lugs at the TV transformer/balun ends of the wire should be stripped before crimping on the terminal lugs to ensure contact with the antenna wires when you attach the TV transformer. Ensure the 75 ohm coax feedline that you connect from the balun/transformer runs away from the antenna at as near a 90 degree angle as possible. Unknownnoreply@blogger.com0tag:blogger.com,1999:blog-1468278518116080443.post-39014352114547730152014-04-30T03:37:00.002-07:002014-04-30T03:37:27.588-07:00Homebrew Folded dipole FM antenna<div dir="ltr" style="text-align: left;" trbidi="on">
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