This circuit is a circuit diagram fm transmitter. Transmitter circuit described here has the additional RF power amplifier stage, after the oscillator stage, to increase the power output of 200-250 milliwatts. With a good matching 50-ohm ground plane antenna or multi-element yagi antenna, this transmitter can provide a good enough signal strength to a distance of about 2 kilometers.
Long Range FM Transmitter Circuit – [Link]
This project shows how to convert a simple FM transmitter to a miniature TV transmitter. Just change the input from the audio to the video (video camera or VCR) and check the signal at your television set. In Europe, for instance, choose the channel 2 – 4 and turn the trimmercap of the transmitter until you see a clear image.
Micro TV transmitter - [Link]
This FM transmitter (FM Tx) is about the simplest and most basic FM Tx it is possible to build and have a useful
transmitting range. It is surprisingly powerful despite its small component count and 3V operating voltage. It will
easily penetrate over three floors of an apartment building and go over 300 meters in the open air. The circuit
we use is based on a proven Australian design.
Simple FM Transmitter – [Link]
This is a small but quite powerful FM transmitter having three RF stages incorporating an audio preamplifier for better modulation. t has an output power of 4 Watts and works off 12-18 VDC which makes it easily portable. It is the ideal project for the beginner who wishes to get started in the fascinating world of FM broadcasting and wants a good basic circuit to experiment with.
4 Watt FM Transmitter – [Link]
This Phone FM transmitter connects in series to your telephone line and transmits the telephone conversation over the FM band when you pick up the telephone handset. Transmitted signal can be tuned by any FM receiver. The circuit includes an “On Air” LED indicator and also provides a switch which can be used to turn off the transmitter.
Phone FM Transmitter - [Link]
This is the basic fm trasmitter that I built. In theory, according to electronics, it shouldn’t work but works fine and is very sensitive. It can transmit the signal up to 45 yards (about 40 meters) . A sensitive FM radio can pick up the signal up to 100 yards (80 meters) but I can’t see any reason for it.
This kind of microphones are also called “spy microphones” but knowing that the battery is bigger than the actual circuit, I can’t see any application like that, anyway, this circuit should be used as educational application only.
Micro FM transmitter - [Link]
Here is a stereo FM Transmitter based on BH1415F wireless audio link IC. Phase Locked Loop controller use Microchip PIC16F628 and the the PLL frequency programming can be displayed with 8×2 and 16×2 LCD display.The frequency range can adjustable from 88-108 MHz.
Stereo FM Transmitter BH1415F – [Link]
This is a small and cheap FM receivers that you can get almost for free. It was based on the KA22429 which is equivalent to a TDA7021. It was easy to move it higher up into the VHF band covering up to more than 160 MHz. The details were published in Sprat in the Winter of 2004. [via]
Single chip VHF receiver - [Link]
The Hamtronics R139 WX FAX Receiver is a 5 channel crystal controlled receiver specifically intended for reception of the polar orbiting weather satellites that broadcast on the 137 MHz weather band. The receiver has a wideband IF that allows for reception of the wideband FM signal from the satellites. The received audio from the receiver is passed to a computer sound card where a program such as WxToImg is used to decode it to an image.
The R139 can scan the 5 channels and automatically stop on an active channel. This works well provided one has a strong signal. If the signal is weak or subject to fading the squelch will close and the scan will resume during the satellite pass which results in a truncated satellite image. For reception of the satellite pass horizon to horizon manual selection of the received channel and running with open squelch is needed. [via]
USB Computer Control for the Hamtronics R139 WX Satellite Receiver - [Link]