2 boxxxx :)

[scs]

High frequency receiver coil must have shield .Detector does not work with missing shield .

[totob]

Thank you DDM and chemlec for the explanation

[totob]

High frequency receiver coil must have shield .Detector does not work with missing shield .

Of any substance making this shield ?

[scs]

Make this shield of aluminum foil with 5 mm overlap.Receiver and transmitter battery and PCB must be not together.Receiver PCB-shielded .Receiver coil connection-with shielded cable.Receiver and transmitter make in resonance.This is valid for high frequency-20-200 kHz Receiver - transmitter detectors.

[totob]

ok scs i will make these modifications.
What will happen if i modifying the size of coils, say 40/30 cm?
Also how many number of turns i need?

[scs]

If used 70 kHz frequency 24 x 24 sm.

[totob]

..Receiver PCB-shielded .Receiver coil connection-with shielded cable.Receiver and transmitter make in resonance detectors.

Do you mean i make it like this pic

[scs]

Receiver coil.

[scs]

Receiver coil-Scheld cable connect to mas\minus| PCB

[totob]

The Transmitter Draws considerable Current.
Just a Small 9 Volt Battery is Not very good.
You need a Higher Amperage Battery.

can i use this 12 v battery?

[scs]

The best battery variant-in the photo.Joke-400 mAh Li-Mh is normal for use.

[totob]

After i changed the battery of receiver to higher Amperage battery, now the power of receiver increased and stable.so i cane make Distance between coils 90 cm
I separate the transmitter and receiver circuit from each other and i shielded the receiver coil but the result of detection is the same (very Weak ),
sensitivity only to big object (like microwave) at distance 30cm.
I don't know where i make the mistake.
please can you check my previous board

[totob]

can anyone check these boards, help please

[totob]

After i changed the battery of receiver to higher Amperage battery, now the power of receiver increased and stable.so i cane make Distance between coils 90 cm
I separate the transmitter and receiver circuit from each other and i shielded the receiver coil but the result of detection is the same (very Weak ),
sensitivity only to big object (like microwave) at distance 30cm.
I don't know where i make the mistake.
please can you check my previous board

[porkluvr]

tobob,

you should use either mica, polystyrene, or polypropylene for the transmit tuning capacitor.

This is not a high power transmit circuit but you should use quality components to get the most out of it.

If you need help, it might be useful if you were to show the reverse side of your PCBs and identify the transistors in your pictures!

Also, what coil(s) are you using now?