Chemelec TR detector

[Jafar]

Add a 10 nf capacitor, in tx circuit

Ok i do it

[Carl-NC]

“The two images with higher voltage are related to TX, and the single image with lower voltage is related to RX. I used 28AWG wire for the winding.”

I don't know what nodes you are probing. You should use 2 probes, place one on each side of the TX coil, and mathematically subtract them.
On the RX coil, probe the output of the preamp, IC1-pin14.

“Carl, I changed resistors R16 and R17 from 1.2 kΩ to 100 Ω in order to increase the TX voltage, but it didn’t make any difference.”

No, they will make little difference except to make power go up. Leave them at 1.2k.

[pito]

The purpose of using H bridge is to increase the power of the transmitter. A low current indicates that the transmitter's LC is not in resonance with the applied frequency. Increase/decrease C12 to obtain the maximum coil voltage (what do you have now?).

this you should have between emitters 12V, your first pic indicates low coil Q, use thicker wire



Problem with Rx coil nulling = you don't have shields on both coils.

[Jafar]

I don't know what nodes you are probing. You should use 2 probes, place one on each side of the TX coil, and mathematically subtract them.
On the RX coil, probe the output of the preamp, IC1-pin14.



No, they will make little difference except to make power go up. Leave them at 1.2k.

"Carl, what do you suggest I do now, and what things should I change? I’ve been away for a few days and couldn’t make any changes."

[Carl-NC]

I have no idea.

[carl1123]

My detector is also showing 1.25V on the meter, how do I fix this? It doesn't matter if I move the transmitter coil, the reading doesn't change