RV101 calibration

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12-Nov-2019 08:57 AM

apper

apper

Posts: 8

Any practical tips as it's (for me) almost impossible to to get in the 10mV range so absurd sensitive the setup is. (btw it is even so in LTSpice.....)


 

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12-Nov-2019 09:43 AM

EJP

EJP

Posts: 1676

Make sure the transistor is working first. Replace with BC549 if necessary. Make sure the VR is 2K or more across the outer terminals. Replace the 2k2 resistor with 1k8 if still necessary.

EJP

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12-Nov-2019 10:12 AM

apper

apper

Posts: 8

ok, will do!
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29-Nov-2019 03:04 PM

apper

apper

Posts: 8

Left channel bias is reasonable stable at 10.20mV, alas the right seems very temperature sensitive and fluctuates  from 10.00mV to 11.00mV.

The only real temperature dependent in this is Tr107?

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02-Dec-2019 02:01 AM

EJP

EJP

Posts: 1676

10-11mV is on the high side but as long as it's stable and doesn't run away over a period of at least ten minutes it's OK. You could try changing the 2K2 resistor around Tr107 to 1k8 to get more adjustment range.
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