PI-1 timing circuit and coil

[Serafin]

HI:

I build the PI-1 op-1 and work but the coil not detect the metal, I it already fits the potenciometers and it does not pass anything, it verifies the voltages and its well and the coil has current. That I can do?

I uses NE5534N

[Carl]

Re: PI-1 timing circuit and coil

Did you fix the cap values I just posted?

- Carl

[Serafin]

Re: PI-1 timing circuit and coil

yes. I fix the cap values posted and the new C10
and use a coil of 20cm diameter and 27 turns of wire No.26.
the circuit work and the speaker sound and the pots control work but the coil no detect.
this problem is in timing circuit or multivibradors?
you have this progect working?
I uses MM74HC221 this can have the problem?

thanks carl.
best regards.

[Serafin]

Re: Carl help! PI-1 timing circuit and coil

hi carl

I am install a jumper in ic7(cmos4066)in pin 1 and 2 and the metal detector work but poorly
in my project I install r23 a resistor of 200 ohms its the problem?
what it happens?

thanks