Author Topic: input bias servo with OP177FPZ  (Read 9330 times)

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Offline fantast

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input bias servo with OP177FPZ
« on: December 27, 2011, 07:42:04 PM »
heaveno,

I have some OP 177FPZ in spare. Was it possible to use them for the input bias servo OPs without any changes?

Kind regards
Claus

Offline peranders

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Re: input bias servo with OP177FPZ
« Reply #1 on: December 27, 2011, 07:50:28 PM »
It should work.
/Per-Anders Sjöström, owner of this forum

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Offline fantast

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Re: input bias servo with OP177FPZ
« Reply #2 on: December 27, 2011, 11:10:39 PM »
Thanks Anders,

I assume I shall remove C61/62 and G61/62 if I am going to use them in the input bias servo?

(And possibly I will also do not need the Zeners DZ9 and DZ10).

Many regards
Claus

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Re: input bias servo with OP177FPZ
« Reply #3 on: December 28, 2011, 06:28:37 AM »
Correct and the zeners will go also.
/Per-Anders Sjöström, owner of this forum

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Offline fantast

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Re: input bias servo with OP177FPZ
« Reply #4 on: December 28, 2011, 11:03:23 AM »
What about the tendency to put DC back into the MC System in your design?

Offline peranders

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Re: input bias servo with OP177FPZ
« Reply #5 on: December 28, 2011, 11:18:31 AM »
The input servo avoids this.
/Per-Anders Sjöström, owner of this forum

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Offline fantast

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Re: input bias servo with OP177FPZ
« Reply #6 on: December 30, 2011, 12:29:39 AM »
Maybe a silly question, but how was it necessary to have a 8slot wago for power supply, as only 5 channels seem to be sufficient (R+/R-/L+/L-/Ground)?
Kind regards
Claus

PS: Finsished with the soldering now and putting the power supply to it...

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Re: input bias servo with OP177FPZ
« Reply #7 on: December 30, 2011, 06:21:28 AM »
You can have one or two power supplies.
/Per-Anders Sjöström, owner of this forum

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Offline fantast

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Re: input bias servo with OP177FPZ
« Reply #8 on: December 30, 2011, 02:32:45 PM »
Thanks,

now the hard stuff. It is running, however I am missing the left preamp part (no diode, no output). Any good idea where to start to find the failure?

Best regards
Claus

Offline peranders

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Re: input bias servo with OP177FPZ
« Reply #9 on: December 30, 2011, 08:13:48 PM »
What is your problem? I'm not sure what you mean.
/Per-Anders Sjöström, owner of this forum

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Offline fantast

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Re: input bias servo with OP177FPZ
« Reply #10 on: December 31, 2011, 12:37:10 AM »
I have checked all connections and parts and everything seams to be OK so far. However, I have a big unbalance at the crossing going to R16 and to R17. Via R8 and T2 the the voltage in around 6V wheras it is just 0.6V the way across R9 and T1. I am not sure where this is from.
Also the DC adjust (after R29) is constantly increasing, starting 5.2V going up to 8V within in few minutes.

Kind regards
Claus

Offline fantast

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Re: input bias servo with OP177FPZ
« Reply #11 on: December 31, 2011, 02:03:08 PM »
OK.
It was the Zener DZ1 :roll:
Regards
Claus

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Re: input bias servo with OP177FPZ
« Reply #12 on: December 31, 2011, 03:17:39 PM »
It is running. First impression is quite good  :wink:
Thanks Anders

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Re: input bias servo with OP177FPZ
« Reply #13 on: December 31, 2011, 03:19:01 PM »
Good news!
/Per-Anders Sjöström, owner of this forum

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Offline fantast

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Re: input bias servo with OP177FPZ
« Reply #14 on: December 31, 2011, 05:14:02 PM »
Next time I am at Chalmers or VTI I will give you a call.
Cheers,
Claus