velosity1 Posted June 11, 2004 Report Share Posted June 11, 2004 Basic FM TransmitterCHECK ATTACHMENT Notes:Transmitter designed for FM broadcast band, 2 meters, and other VHF bands by changing values of C5 and L1. values given will set transmitter somewhere in FM Broadcast band. L1 is 4 turns of #20 enameled wire (airwound) 1/4 inch diameter, 5mm long and center tapped. Microphone is Electret type. Antenna is 18 inches of any wire. Try to keep all leads as short as possible to prevent stray capacitance. Range of transmitter should be several hundred yards..............................................................................................................OK what does this mean and how can I build this .... what parts do I need ?? please help im a newbie in the electronics filed well not really I have some experience in making kinds of wires for xboxes and usb stuff :)tnxvelosity Quote Link to comment Share on other sites More sharing options...
xwarp Posted June 11, 2004 Report Share Posted June 11, 2004 the value of C5 and L1 pretty much controls the "carrier" frequency. basically like a radio station. the carrier is 97.5, your receiver picks up the carrier, removes the carrier, and what is left turns into audio. reason for keeping all connections short is because this affects the tuning of C5 and L1. example: if you do the math for C5 and L1 and have a result of 102.7 MHZ and any of the wires that connect to L1 are 6 feet long and just kinda looped here and there, you have basically created an inductor which changes your frequency.hope this helps. tried to keep it simple and correct and if it's not correct, i'm sure someone will correct me. Quote Link to comment Share on other sites More sharing options...
velosity1 Posted June 12, 2004 Author Report Share Posted June 12, 2004 thnx now that I know that how do I build it .......what parts do I need ???tnx again :) Quote Link to comment Share on other sites More sharing options...
Kevin Weddle Posted June 12, 2004 Report Share Posted June 12, 2004 Sometimes I think that the values chosen for RF applications are just in the neighborhood of being correct. You could narrow your design work quite a bit by choosing component values that are within reason. All you have to do to get it close is to know the impedance and of course properly DC bias it. As far as filtering, why bother. You know the frequency and two bandpass filters is as good as a bandstop. Quote Link to comment Share on other sites More sharing options...
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