FM Band PreAmplifier:  (circuit / schematic design added 6/06)

FM Beacon Transmitter (88 108 MHz):  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.

FM Booster:  (electronic Circuit / Schematic added 10/04)

FM Bug #2:  (electronic circuit added 4/05)

FM Oscillator :  ASCII format (circuit design added 10/06)

FM Radio Telephone Bug:  (circuit added 7/02)

FM Radio Transmitter #1:  (circuit added 7/02)

FM Radio Transmitter #4:  (schematic / circuit design added 9/02)

FM Radio Transmitter:  (circuit / schematic design added 6/06)

FM Stereo Modulator:  (electronic circuit added 10/05)

FM Telephone Bug:  (circuit added 9/04)

FM Transmitter #3:  (electronic circuit added 10/05)

FM Transmitter #4:  (circuit / schematic design added 6/06)

FM Transmitter #5:  This simple transmitter operates from a 9V battery as shown above. I personally built this for a purpose. This is how it happened:"members of my singing group find it difficult to handle a FM mic in Church. The choir sings in acapella form and the congregation expect us to perform well. The old FM mic system was not a perfect solution, so I built this kit and a mixer for the receivers. using three separate transmitter circuits and a mixer on the receiver, the choir voices were perfect and cleanly reproduced."  From the notes I made experimentally, C3 is vital to the circuit and without it the circuit may become unstable. C4 is in parallel with C5 and presents a moderate load impedance. Finally all transistors are NPN. The circuit works well and has proved reliable.  (added 6/06)

FM Transmitter #6:  (electronic circuit added 4/05)

FM Transmitter 1km Range (88-108 MHz):  1KM Range  (added 11/05)

FM Transmitter with Opamp:  L1 is 0.112uH (this tunes to the middle of the FM band, 98 MHz, with VC1 at its centre value of 33pF). L1 is 5 turns of 22 swg enameled copper wire close-wound on a 5mm (3/16") diameter former. Alternatively, you can have a fixed 33pF cap instead of VC1 and have L1 as an adjustable molded coil (eg UF64U from Maplin). VC1 will give you a tuning range of 85 125 MHz, and a possible choice is the Philips type polypropylene film trimmer (Maplin code WL72P). Two sets of oscillator bias resistors are given, the ones in the brackets give about 20% more RF power. Mike is our favorite Omni directional sub-mini electret (Maplin code FS43W). Ant is a (lambda / 4) whip monopole (eg 76 cms of 22 swg copper wire). Q1 is configured as a Clapp oscillator. Frequency modulation results from the audio voltage changing the transistor's base-emitter capacitance. (added 6/06)

FM Wireless Mike:  low power frequency modulated transmitter using two transistors. The circuit works with 9v power supply. . (added 9/04)