Total PI Gain

[1843]

Hi all,

If we instead increasing the integrator gain, leave it and increase the gain of the after integrator op amp, what will happen?

For example I want to increase total HH gain 10 times, instead changing R26 and R27 to 1M, I add an additional op amp at TP5 with gain 10. This work can keep the integrator TC from changing and also prevent to add to internal noise of the integrator op amp.

Best regards

[Geo]

Hi 1843. If you will change R26 and R27 then the total gain will be 1.000.000. I made detectors with so big gain but had 2 problems. First ...... they was a little "unstable....... or very sensitive to everything" and second problem was to null the output of integrator so without signal to have an output 1....3 V. At some detectors if you increase the gain of the integrator the output goes hight and you lose everything .
Bye

[Kev]

This may help

Hi,
I doubled the DC gain on a Goldquest, but it became very unstable, but by the adition of the feedback circuit paralleled with the fb resistor stability returned. This extra gain gave around an inch more on a one gram nugget.
see details here
http://www.findmall.com/read.php?34,...602#msg-461602

Cheers
Kev.

[Geo]

Hi Kev. Very good work .
Congratulation