My version of the G = 1000 low noise measurement amp (for Ikoflexer)

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#101
Mark Johnson said:
I think so too, as drawn it's positive feedback.

It also doesn't model the fast-light, slow-quench asymmetry of the photovoltaic magic, but perhaps that's insignificant when C6 is added (usecs versus seconds).
Click to expand...

I have tried that with 4*IF3601 and found the regulation is "too good",
at least with 4*IF3601 gm. Vd was nailed down at parts of mV precision; I had the
belly feeling that the loop gain might transport noise back to the input
and also effects that resembled motor boating; but then 4*IF3601 IDss is
much more than the allowed If_abs_max of the Vishay generator.
I was shooting for 0.1Hz lower passband corner and with the necessity
of an even lower input RC for noise reasons I was quickly at settling
times in minutes. At the moment I'm not that patient and I need a negative
supply for the output amplifier anyway, so I went the trusted op amp
integrator route, at least for my current design.
But I watch this here 🙂

regards, Gerhard
 
#102
gerhard said:
I have tried that with 4*IF3601 and found the regulation is "too good",
at least with 4*IF3601 gm. Vd was nailed down at parts of mV precision; I had the
belly feeling that the loop gain might transport noise back to the input
and also effects that resembled motor boating; but then 4*IF3601 IDss is
much more than the allowed If_abs_max of the Vishay generator.
I was shooting for 0.1Hz lower passband corner and with the necessity
of an even lower input RC for noise reasons I was quickly at settling
times in minutes. At the moment I'm not that patient and I need a negative
supply for the output amplifier anyway, so I went the trusted op amp
integrator route, at least for my current design.
But I watch this here 🙂

regards, Gerhard
Click to expand...

That loop was meant for ~1mA Id and a single battery power supply. It was an offshoot of phantom powered microphone circuits where there is no minus supply.
 
#103
Digikey dropped the price of the 2.7Meg and 10.0Meg SMT resistors from $0.10 to 0.015 if i ordered 50 These are P2.7MACT-ND and P10MACT-ND. I also ordered:
56M Ohm ±5% 0.1W, 1/10W Chip Resistor 0603 (1608 Metric) Thick Film
which is HMC0603JT56M0CT-ND

Anyone who wants these three, send me a PM including your email address, and you can send me an SASE, will return same.
 
#105
jackinnj said:
Digikey dropped the price of the 2.7Meg and 10.0Meg SMT resistors from $0.10 to 0.015 if i ordered 50 These are P2.7MACT-ND and P10MACT-ND. I also ordered:
56M Ohm ±5% 0.1W, 1/10W Chip Resistor 0603 (1608 Metric) Thick Film
which is HMC0603JT56M0CT-ND

Anyone who wants these three, send me a PM including your email address, and you can send me an SASE, will return same.
Click to expand...

I tried but could not find a tube of 823's to throw in.
 
#106
hallodeletue said:
Another one coming in - thanks for the effort, guys!

SGK - 1
Lbud4 - 1
luvdunhill - 1
waltzingbear - 2
DNi - 5
Ph104 - 1
Vacuphile - 1
av-trouvaille - 1
hallodeletue - 1
Click to expand...


Gentlemen,

PCBs just arrived.
Please kindly pay HK$100 per PCB to
wkypb AT hotmail DOT com

This will include PCB, registered post (surface mail), and Paypal fees.
We shall ship as soon as we received all payments, hopefully right after Xmas.

Please do not forget we need your :
FULL NAME
DIYA Codename
Postal Address


Thanks,
Patrick
 
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