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RF (Radio Frequency) Transmitter Circuits
RF (Radio Frequency) Transmitter: #'s -
B C - F G - S
T- Z
Last Updated on:
Monday, August 18, 2008 04:17 PM |
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| Links to electronic circuits, electronic schematics, designs for engineers, hobbyists,
students & inventors: |
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Combination-Controlled fully customizable RF remote Control: (added 09/05) |
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Compact 20 14 MHz Direct Conversion Receiver: (added 2/05) |
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Design of
Brookdale ATV Repeater System Exciter: 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
(Electronic circuit added 5/02) |
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Easy 2 Meter Transmitter: 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, Motorola, 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 (added
8/03) |
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FM Band
Monaural Transmitter: (added 8/03) |
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FM Radio
Transmitter #1: (Electronic Schematic / circuit added 4/02) |
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FM Radio Transmitter: (Electronic Schematic / circuit added 4/02) |
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FM Transmitter #2: This circuit is a simple two transistor (2N2222) FM transmitter. No license is required for this transmitter
according to FCC regulations regarding wireless microphones. If powered by a 9 volt battery and used with an antenna no longer than 12 inches, the transmitter will be within the FCC limits....
(added 09/05) |
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FM Transmitter #3: This small transmitter uses a Hartley type oscillator. Normally the capacitor in the tank circuit would
connect at the base of the transistor, but at VHF the base emitter capacitance of the transistor acts as a short circuit, so in effect, it still is. The coil is four turns of 18swg wire wound
around a quarter inch former. The aerial tap is about one and a half turns from the supply end. Audio sensitivity is very good when used with an ECM type microphone insert. (added 11/05) |
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FM Transmitter #4: 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 10/05) |
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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 10/05) |
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Four Transistor Tracking Transmitter: (added 9/02) |
