PI-1 Hamerhead, opt.1 question to all

[Eugenij]

I build opt1, but the sensivity is too bad. Only 30 sm for big cooper jar (10 sm). I tried to decrease R35, but without effect. Also tried to increase R29 up to 300K without any improvement. I have changed IC8 with TL062 and this has some small positive effect, but I am still far far from good sensivity.
Can anybody help me with some suggestions? Thanks in advance!

[Seras]

Re: PI-1 Hamerhead, opt.1 question to all

Hi I build this project opt1 and I detect a 1 cent dollar coin at 23 cm and bottle (cerveza) at 60 cm.
Adjust R42 and R46 and R45 until good sensivity this is the secret and TP4 (IC5 pin3)at 0.7 V, not put C11, R11 680 ohms at 1W.I not put jumper of IC7 pin 8 at ground (positive).

Good luck

Best regards

[Eugenij]

Re:Thanks!

Thanks Seras,
I'll try your sugestions this weekend days.

Regards,
Eugenij