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Hello audioguru, if i don't use an RF amplifier at the output, so are there any onther solution(s) to prevent from frequency drifts or changes when anything gets near the transmitter ?audioguru said:The cheap, cheap FM transmitter circuits change frequency when you get near them because the are simple and cheap and cheap. My FM transmitter has a transistor added to its output to isolate the tuned circuit from the antenna and to boost its output. It goes more than 2km so it is very illegal. I guess its power can be turned down.
My FRS transeivers were a bargain with their crystal frequencies, rechargable batteries, 38 channels and 3km range. I didn't make them and never looked inside them.
There isn't, either build and output amplifier as the schematic suggests or put up with the frequency shifting when the load on the oscillator changes due to reflections.joeypc said:Hello audioguru, if i don't use an RF amplifier at the output, so are there any onther solution(s) to prevent from frequency drifts or changes when anything gets near the transmitter ?
Thank you !
audioguru said:I have seen them in stores.
The good ones have DIP switches to select 4 frequencies near the bottom of the FM dial and 4 more for the high end. That sets up the quartz crystal controlled frequency synthesizer like in the Micromitter project.
The poor ones don't have DIP switches. I can't remember how they are tuned. Maybe just by getting near them.