geophone kit circuit reqest

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the 741 inverter circuit in this also works without a battery

It doesn't work with its inputs at the negative supply voltage, and it has many other problems. So the 741 works like a piece of wire.

The LM386 amp has a gain of 200, which is plenty. Try the coil connected like this:


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thankyou audio guru ill try that one to, all though there are more 741 circuits on the net to and the one i used before was one of them so i welcome the extra. oh by the way i tried that circuit you said to try and its not very good it dont work, the powerfull rare earth magnets have to be sitting on top of the coil and moved, like brushing it to get any reaction, from the audio amp , however the latest way i have it set up its so sensitive that i dont have to swing the magnet, i can raise it and lower it and get an effect in fact at nearly 10mm is pritty great range  thats with the magnet away from the coil , and with the 1k and 10uf  removed from the 741 circuit, and i taped to the led leg  before the 10 ohms resister  and i conected the other coil input to somewhere else , now  my nine volts batteries aint full charge so the second was just a helper and when i removed the 9 volts battery from the preamp section it still worked , by just the induced voltage into the coil from the slightest movement of the magnet  and with the battery back in its more responsive , and even though it aint audio signal i think, to be boosted  at least im getting some form of sound from the amp section. ive saved that latest you posted so il be trying it to

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