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Topic: Simplest AM radio receiver (Read 14023 times) previous topic - next topic


s there anything known as variable inductor

Yes you made one by sliding the rod part way out of the coil.

how do u have so much knowledge

Well I started at an early age and have now reached a much older age. My first job in electronics was in 1966.


wow! i plan to do that exactly  :smiley-eek: im in my gcse's and ive covered pretty much in electronics. also is it possible to make a LC circuit in the mhz range that would pick up fm in the same way? i understand the demodulation would be different.

Runaway Pancake

You can't just jump to FM like that.
Well, at least add regeneration, get some selectivity.

"Who is like unto the beast? who is able to make war with him?"
When all else fails, check your wiring!


oh yes i was thinking about that, im being too erratic :/ i agree i will first understand Am fully. What is regeneration?

Runaway Pancake

May 08, 2012, 02:04 am Last Edit: May 08, 2012, 02:38 am by Runaway Pancake Reason: 1
I dug out my Regenerative hybrid.
It has a varactor diode (MVAM109) for tuning, I used a voltmeter as a tuning dial.
It uses an NPN transistor for the regeneration.
I'll have to hunt around for the circuit.
There's a LM386 power amp, too, just for kicks.



* * * I found that schematic.  I tucked it inside one of my books.  It's with the other pics in the 'photobucket' link above. * * *
"Who is like unto the beast? who is able to make war with him?"
When all else fails, check your wiring!


Well in theory you could demodulates FM with a crystal set, by using slope detection. This is simply off tuning the signal so it sits on the slope of the selectivity curve. In practice you just tune for maximum volume.


Thanks again everyone. @runaway thanks for the photos nd circuit. i also dont get one thing in some basic crystal recivers there are 2 caps. one is in the lc circuit while one is connected to the diodes cathode to ground. what does this do?

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