hello pahom and everyone. the device does not detect a battery spark at any distance. the oscillator is used but I need to put an extra switch to understand the difference in the operation of the circuit. I will know by evening. the important thing is that I do not know at what points in the circuit I need to measure with the multimeter and the oscilloscope to know that the oscillator excites the receiver as much as necessary.

the oscillator used is this one.

I also put a switch on the oscillator and it seems to make a huge difference. With the oscillator off, it doesn't detect the pen at all. With the oscillator on, both the 741 and the sound generator detect the pen. If I turn off the 741, it detects the pen again (how is this done). The oscillator's power cable works like an antenna and seems to be more sensitive than the small loop. When I turn on the oscillator and sound generator, I have the longest detection distance for the LED lamp I have. And for the radio I have. Once the 741 is on, the distance decreases but the sound becomes more stable. It is also very important that the battery cases are very well secured so that it doesn't make false sounds. Also, when I grab the paper box with both hands, the distance decreases again.

When the oscillator is turned on, the timer 555 must have the maximum sensitivity of the device. well, accordingly, the detection distance is greater. That's when you turn off the LM741 amplifier and your device works.... that's where the miracles are.

:oh:

I have started building the box.

Does the box need to be connected to ground?

Judging by the photos that are publicly available, the original has no shielding.

hello everyone. so I have placed all the circuits inside the box and the receiver circuit with the loops on the top of the circular box which is also metal and I noticed that it no longer detects the pen I rub on the clothes now it only catches a piece of plexiglass when I rub it. also it no longer catches any LED bulb while in the paper box it caught it from one meter. now it catches the screen from the radio only when I touch it while before it caught it from half a meter. why does the antenna box have to be metal??? is the function I describe correct??? what tests are there to know if it works as it should???

the cylindrical top antenna it's not made from metal - the way you build it acts as a short circuit for signals.
I think is made from plastic, I will check to be sure.

Hi Bill 512. If you mean the cylinder where the oscillator is located, I have a φ50 pvc pipe and there on top is the small receiver loop. I fixed the problem that it doesn't detect. Now it detects again but not at the distance it detects when it is in the cardboard box. (Thank you very much for answering, if you have any information you would like to share that would be very helpful.)

Are you talking about the big cylinder or the oscillator tube???

Finally, does anyone know what material the large circle is made of? Is it iron or plastic????

Hi Zico! This circuit is only two transistors, 741 and 555 stimulator and a 555 sound or do you have it with the radio tda 7000? Good job anyway!

Hi Kostas 87, thank you for your comment. I don't use dta 7000. Do you think it's necessary?