Thursday, December 29, 2011

6500K AM transceiver

After the build of the 6500K AM modulator I had to do a compatible receiver. Following the tests with the green LED's I thought they were the right candidates to "antennas"...

before the receiver part build I made a small audio oscillator since it's easier to test with a steady source than a mic, this one oscillates around 1100 Hz.

The oscilator "out" after the pot and 0.22 cap connect's directly to the transmit driver input:

There is nothing simpler, not high performance of course...

Receiving part is just the 2 green LED's connect directly to the input of an LM386 amplifier with 200x gain. Standard from datasheet and no input level pot.

And here the prototype in test:

I got 1 inch range before signal get's to low, in fact signal is just near the noise floor of the LM386, an preamplifier would increase a little bit but using LED's as light receivers isn't the most efficient way of doing things, an LDR or a phototransistor will do a better job for sure. Anyhow it's just a proof of concept....

Have fun!

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