autotrak sw2 vs ic7d

[lucas]

Hi

Possible this modification? (Autotrak with IC7d)
Thanks

[kt315]

with SW2 opened HH works very unstably. simply connect it and do not use the switch.

[lucas]

And nobody "guard gnd"?

Thanks.

[Carl-NC]

I don't understand the point of ading IC7d. Looks like it opperates the same way as just the switch.

"with SW2 opened HH works very unstably."

With the TL072, it's stable for several seconds, long enough to do a no-motion pinpoint. To get longer stability, you would need to replace the TL072 with a true zero input current CMOS opamp.

- Carl