gary Metal Detector

[yhl]

我完成了我的一部分

[WM6]

我完成了我的一部分 I finished my part of the Gary PI MD

Congratulations yhl.

Are coin findings on last picture yours, done by Gary PI, or out from local museum?

[yhl]

Adjust the potentiometer VR1 of the voltage of 1V, the legs 6 IC9 occur.

Adjust the potentiometer VR1 of the voltage of 1V, the legs 6 IC9 occur.

[yhl]

Need help

I do a circuit. But not enough depth detection / 2.5CM coins only 10CM.
Circuit the total current only 55 mA. If there are problems?
Points are normal voltage

[oros27]

即線圈的問題？

[Qiaozhi]

即線圈的問題？

Possibly.
yhl - what are the coil details?

[oros27]

即線圈的問題？

Approximately 12 inch OD and wound with a 20 1/2 AWG.
Approximately 26 Turns
Inductance, Approximately 400 uhy measured at 1 Khz.
DC Resistance aprox 0.8 ohms.

[yhl]

Thank you

There may be / I is a 0.51CM line. Diameter 20CM, 30 laps of the BFO coil

[Qiaozhi]

There may be / I is a 0.51CM line. Diameter 20CM, 30 laps of the BFO coil

That will give you a coil of around 513uH which should be ok.
Do you have an oscilloscope?

[yhl]

hello

I have no oscilloscope. I just want to ask the next / coil does not match the current will become smaller?>

[Qiaozhi]

I have no oscilloscope. I just want to ask the next / coil does not match the current will become smaller?>

Then it is difficult to see what is happening to the RX signal. You might need to adjust the value of the damping resistor.

[yhl]

hi

But the current of the circuit is the work of only 55 mA. Each voltage is normal. Electronic parts no problem.

[yhl]

I want to know

I could try to build a coil. I just want to ask why the current only 55 mA under?
Q1 IRF740. I used the 6N60 replaced. Parameters of the same

[yhl]

LOOK

[Help] display IRF840 What could be better than the tube?
IRF840 500V 8A 125W NMOS field effect transistor can be substituted with a common 6N60

[Qiaozhi]

But the current of the circuit is the work of only 55 mA. Each voltage is normal. Electronic parts no problem.

I agree. The quiescent current seems to be on the low side. Maybe the TX pulse width is too small or you need to increase the frequency. I would recheck the component values in the TX driver circuit.