Andy Flind MFD.

[Geo]

Radio is not the primary detector so don't spend so much time for it....

[abdou2014]

primary detector is the ANDY circuit, to begin , what is the resonance frequency of a receiver coil ?

[Geo]

There is n't magic frequency!!!!
Tune it near to 80Khz and its fine!

[abdou2014]

Thank you for your help

[abdou2014]

ANDY 4016 circuit has low output, almost I can't hear ringing, it is necessary to modify this stage and add something for speaker .

[Geo]

As i remember Andy's output can drive a speaker but you will not have the beep at max signal.Output signal of 4016 increases with the the increase of the input signal as the mdetectors at nomotion mode. This is the reason that we connect a beep generator.
But the problem is that we need a new design....
Until then you can keep the beeper far from the coil

[Pahom]

As i remember Andy's output can drive a speaker but you will not have the beep at max signal.Output signal of 4016 increases with the the increase of the input signal as the mdetectors at nomotion mode. This is the reason that we connect a beep generator.
But the problem is that we need a new design....
Until then you can keep the beeper far from the coil

What will the new scheme change? If the noise on the circuit comes from the speaker, then the circuit has nothing to do with it. If there is interference inside the circuit, then you need to make a galvanic isolation or power the sound generator from a single power supply.

[abdou2014]

Now it's Ok , very stable circuit with 3 volts supply

[Pahom]

Now it's Ok , very stable circuit with 3 volts supply

What are you powering from 3 volts?

[abdou2014]

streatcher and oscillator

[Pahom]

streatcher and oscillator

Well, the oscillator is clear to me and what it is for. But what is (the stritcher) did not understand. Maybe not a correct translation.

[abdou2014]

pulse extender or fast pulse receiver

[abdou2014]

the oscillator to drive the speaker

[Pahom]

pulse extender or fast pulse receiver

Thank you, I understood what I was talking about. I have such schemes. And they also work from 3 volts. True, not a lot of non-standard use of microcircuits, but the caffeinth signal-noise is much better than on the LM324

[Geo]

Finally i did n't find solution for the beeper so i moved the beep generator far from main pcb and coil.
Now it works fine!!!, i can adjust it at full sensitivity without any problem.
It don't need any other mod, so now i wait for a good T.H