A TRF Radio
A bit of back to basics - remember the ZN414 radio chip?
Well there have been a couple of revivals, one version being the TA7642 chip, identical to the ZN414 electrically. I have put together a simple design, that works well, with very good quality (and loud) sound into a pair of walkman headphones.
Very low power consumption of less than 2ma will give months of 24/7 listening with a single aaa battery.....Now stick that in your MP3 player and smoke it!This is "Furcot Version" of the design in the old ZN414 application notes - I have bent the rules a little, so plugging in the headphones turns on the power. In the prototype a stereo jack socket was used, as this results in a "normally open" connection, if the "tip" and "barrel" connections are used - the 64 ohm walkman headpones work fine as the series load for the circuit - indeed the audio quality is stunning!
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