Electronics-Lab.com Blog

Fred points out this schematic for a rather interesting radiotelephone transmitter instantaneously powered by the operator’s voice. [via]

One of the neatest minimalist amateur radio transmitter circuits around – this one is voice powered – it provides DSB, (double side band)modulation and power from an ordinary 8-ohm speaker – if are in doubt that the circuit works, the maker has the contacts and the voice recordings to prove it!

Voice-powered RF transmitter - [Link]

josepino.com writes:

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]

If a crystal radio is the distilled essence of a radio, this transmitter is the matching distilled essence of transmitters. The transmitter goes together in about 10 minutes, and is small enough to fit in the palm of your hand. Depending on the antenna, the transmitter can send voice and music across the room, or across the street. [via]

Building a very simple AM voice transmitter - [Link]

This is a really cheap and probably illegal shortwave transmitter, don’t build it. It just feeds the output from an LM386 audio amplifier directly into the power pin of a crystal oscillator can to produce AM-modulated shortwave radio frequencies. This works better than one might expect — this particular oscillator seems to provide a stable waveform with voltages anywhere from 2.0v to 5.0v! [via]

Cheap Shortwave Transmitter - [Link]

This is wireless FM transmitter project, when you speak into the transmitter and others hear you on any FM radio. The transmitter can be built in an afternoon with simple, affordable and widely available parts. Construction is fun and much can be learned although performance is modest; for example, your voice gets difficult to hear at distances greater than 25 feet. [via]

Wireless FM Transmitter - [Link]

Wow,this is very cool board-less radio transmitter designed by Shadle who is the member on flickr.com. He is assembled this intricate radio transmitter circuit for the QRP Kits Pacificon building contest.It very amazing No PCB.This circuit can transmit frequency between 7.039MHz and 7.041MHz. [via]

Board-less radio transmitter - [Link]

This is a single transistor FM transmitter that is about the size of a standard AA battery. The site has all the schematics and technical specifications needed to complete the project. Let the bugging begin! [via]

Simple FM transmitter - [Link]

Here is how to make a 2-channel RF transmitter and receiver that works on the 418 MHz frequency. Unlike IR remotes, this one can work through walls and at a greater distance too. It’s perfect for closing the garage door or anything else that you are too lazy to get up and do. [via]

2-channel RF Transmitter - [Link]

Mathieu writes -

I whipped up a little interface yesterday, to connect an Arduino to a Radio Control Transmitter. This can be used to send commands from the Arduino to the transmitter, which will mix them with the manual input and radio them to the radio-controlled model.

The Arduino is sending commands (PPM-encoded series of servo-position pulses) to the RC transmitter (a Multiplex Royal Evo 12, in this case), which mixes them with manual input and radios them to the radio-controlled model.

You can see on the transmitter’s display that channels 1, 2, 4 and 5 are broadcasting values while the sticks are centered. If I had video, you could see them change over time under the Arduino’s control.

Arduino to radio-control transmitter interface – [Link]