Car anti theft wireless alarm.:  This FM radio-controlled antift alarm can be used with any vehicle having 6to 12-volt DC supply system. The mini VHF, FM transmitter is fitted in  vehicle at night when it is parked in  car porch or car park. The receiver unit with CXA1019, a single IC-based FM radio module, which is freely available in  market at reasonable rate, is kept inside. Receiver is tuned to  transmitter's frequency. When  transmitter is on and  signals are being received by FM radio receiver, no hissing noise is available at  output of receiver. Thus transistor T2 (BC548) does not conduct. This results in  relay driver transistor T3 getting its forward base bias via 10k resistor R5 and  relay gets energised. When an intruder tries to drive  car and takes it a few metres away from  car porch,  radio link between  car (transmitter) and alarm (receiver) is broken..... (added 10/05)

Ceramic Filter BFO:  Receive SSB and CW transmissions on your BC receiver. Simple BFO is build around 455 KHz Ceramic Filter. . (added 9/04)

Circuit Transmits Arinc 429 Data:  07)/11/02 EDN Design Ideas  /  (added 1/05)  The ARINC (Aeronautical Radio Inc) 429 specification defines the air transport industry's hardware and protocol standards for the transfer of digital data between avionics systems. Circuitry that can implement elements of the 429 spec is often an essential part of control and sensor electronics intended for the aviation environment....

Ck-3V FM Transmitter:  (electronic design / schematic added 2/05)

Coilless FM Transmitter!:  (electronic circuit added 10/05)

Combination-Controlled fully customizable RF remote Control:  (electronic Circuit added 03/06)

Crystal Controlled FM Transmitter:  (electronic circuit added 7/03)

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 (added 5/02)

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 7/03)

FM Band Monaural Transmitter:  (electronic circuit added 7/03)

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. (added 5/02)

FM Bug (1.859.telia):  (electronic circuit added 7/03)

FM Microphone:  (electronic circuit added 7/03)

FM Radio Transmitter (aaroncake):  (electronic schematic / circuit added 4/02)

FM Radio Transmitter:  (electronic circuit added 9/02)

FM Radio Transmitters with OpAmp :  (electronic schematic / circuit added 4/02)

FM RF Remote Control (88-108 MHz):  1KM Range  (added 11/05)

FM telephone transmitter 2:  (diagram added 05/07)

FM transmitter (aaroncake):  (diagram added 05/07)

FM Transmitter (davidtx):  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)

FM Transmitter (fmtx_dc):  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)

FM Transmitter (radiockt6):  (electronic circuit added 10/05)

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

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

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 (e.g. 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 (e.g. 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)

Four Channel Wireless Transmitter and Receiver:  The Wireless KT4A Transmitter and KR4A Receiver have been designed to offer moredata channels than the original KT418S2 and KR418S2 projects that were published in the April 1999 issue of Popular Electronics magazine (circuit added 5/07)

Four Transistor Tracking Transmitter:  (electronic schematic / circuit added 4/02)

Frequency Agile 80m CW QRP Transmitter:  (electronic design / schematic added 2/05)