AlbertHall
- Joined Jun 4, 2014
- 12,347
So maybe something isn't connected. The track of RV1 should connect to pins 1 and 5 and R10 should connect to the 0V supply output.
Measure the voltage across R10.
Measure the voltage across R10.
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The gain of U2 is obviously 1+ (56k/27k)=3.074 times. The IN+ is 9.8V so the output is trying to be 30.13V which is impossible since the Vcc is much less.Can someone explain why U2 only outputs 22.5V while:
Vcc+ = 28.5V
IN- = 6.7V
IN+ = 9.8V
I found now some articles of fake tl081. Those do not seem to have a valid circuit for OFFSET NULL 1 and 2?
Does this have influence on the output of U2?providing it with a current that is much too low at 5.6V/4.7k= 1.2mA so it barely regulates
Of course since one input of U2 is from a divider of the reference.Does this have influence on the output of U2?
I checked the pinout of Q1, it is good. (what is the function of this transistor?)The very low output from U2 might be because it is a Chinese fake?? Maybe Q1 has a backwards Chinese pinout??
Thanks for explaining this to me, I learned a lot by building this crappy board.The TL08x and TL07x opamps have the "Opamp phase Inversion" problem
by Aaron Carman
by Aaron Carman
by Jake Hertz
by Jake Hertz