JSR03 going a bit nuts on me

[peranders]

You should be worried if the temperature is over 100 deg C. 60 degrees is not much for the transistor itself but electrolytics may be "tired" shorter than expected.

The current should be not more than needed for good operation.

[raq]

P-A,
Operation continues to be stable.

Let me ask you - what do you think about using AD797 or LT1028 with my voltages and everything else? For reference, I am right now using LME49710.

Thank you,
Radu.

[peranders]

LT1028
SUPPLY VOLTAGE
> 9 volts supply voltage
INPUT COMMON-MODE VOLTAGE RANGE
> 2 volts in at the inputs

AD797
SUPPLY VOLTAGE
> 9 volts supply voltage
INPUT COMMON-MODE VOLTAGE RANGE
> 2 volts in at the inputs

If you can make sure you'll have 10-12 V for the opamps they might work but I haven't tested.

[raq]

All checked... With R12 used, the Vcc should be between 12V and 15V (15V most likely).
Vref is 2.5V, so this is accomplished too (Vin+, Vin-).

If I build the 3.3V PS, I might use 1.25Vrefs, things will not check anymore.

Thank you,
Radu.

[peranders]

You must be aware of the common mode limits. It means how near the inputs can be the supply voltage and ground. If the inputs are out of the common mode limit the opamp may not work properly but no harm in testing.

[raq]

Alright then - assuming I use any of the mentioned op/amps, I believe likely have a common mode limit above 2.0V. If Vref stays 2.5V, with an R9 of 1k, having R8 = 320ohm should hit my target of 3.3V - is that correct?

DZ1 could be a green or red LED provided it hits 1.65V over itself.

Please let me know - thank you,
Best,
Radu

[peranders]

Using a 2.5 V ref is wise and some sort of red, yellow or green LED may work. Make sure that the opamp output is within it's limits. You can measure this but if you have a stable output voltage it will probably work. the potential at R10 must be exactly the same as the + input. If this is the case the opamp is regulating properly.

Correct with the resistors.