![]() ![]() More amplification means more higher fm transmitting power and longer range. The amplifier's job in this circuit is to take the audio input and beef up the voltage/current so that when it gets transmitted it travels further. The input is pulled high with a 22k resistor and passed to the amplifier circuit. You could shop around for a smaller microphone I'm sure but for this project, a standard electret microphone does the trick. The far left side has the electret microphone and then things move electrically to the right until they hit the antenna.ĭon't let this microphone fool you, it's extremely sensitive albeit a bit clunky and big. In total there are 18 core components that are needed for the fm transmitter to work properly. So save yourself the hassle and (a) test the circuit out before putting it into the fm bug mint box and (b) don't use a metal mint box. The project will not work if it's inside of a metal box, there's just no way. Please don't use a tin mint box, I can't stress this enough. Copper Clad PC Board is relatively cheap and widely available just like ferric chloride, so don't skimp out, it's cheap and available use it! You really need to use either perferoated board or a pc layout board like I'm going to use in this project. This circuit will not work on a breadboard, period. Again these are mission critical values unless you have an LC oscillator calculator infront of you, and you know what you're designing. Two of these capacitors are used in the oscilllator circuit. ![]() Be sure to get AWG 18 when buying it because the diameter does make a difference when building parts and making coils for this project. This is standard copper wire, we'll be using it to make the RF coil in the oscillator as well as for the antenna. Further more, they're not even expensive. I would not substitute any other general use transistors like 2n2222 or 2n3904 when building this one, simply because the BC547's work. These are tried and true HAM radio transistors, use them for this project. Below I've described the most important parts for the project. The rest are just resistors, capacitors and inductors. Why not instead have some fun with it?įor the most part, all of the parts used in this project are discrete and passive, with the exception of the transistors, which are the only real 'active' part of the circuit. The reason I'm not trying to invent something new here is simply because FM transmitters have been redesigned to death. Two transistor FM transmitters and FM bug circuits are all over the internet and they all share a common design that will be followed in this project as well. ![]() So we've already seen mint can MP3 players and mint can amplifiers for guitars and tons of other projects, why not an FM bug transmitter? Well for starters, a tin can would be the worst place to put an fm transmitter! Luckily I stumbled upon this plastic mint box and thought.why not? ![]()
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