enter image description here

I use Arduino Pin to make PWM and give input to Op Amp LM324.

I would like to know, why my op amp has difference output. I have gain 2x. I multiply input from 0-5 Volt to 0-10 Volt because the gain is 2x. Output Pin 1,7, 14 is okay (has similar voltage).

But in output pin 8. It has different voltage almost 1 Volt. Let say Max Output for Pin 1,7,14 is 10.00. Then, pin 8 has around 9.1 Voltage.

How could be like that? I try to change my IC with new one. And has some problem. Why does it go?

My circuit is okay also. I double check my circuit.

Edit (Attach circuit)

enter image description here

RG = RF = 100 kOhm

Vin = 0-5 Volt

Vout = 0-10 Volt

I ground all of in one point. Also with Ground of Arduino. All of other 3 op-am is typically same circuit as above.

  • 4
    \$\begingroup\$ "My circuit is okay also" No you think it is OK. That doesn't mean it is OK. Maybe it just doesn't work as you expect, maybe your expectation is wrong. Still, you have to show the circuit. You will get no usable answers without it. I am too lazy to read: pin 1 = bla V, pin 2 = bla V and many others with me. \$\endgroup\$ Feb 29, 2016 at 11:05
  • 1
    \$\begingroup\$ It's all about the circuit... and the supplies... and the load.... and the bypass capacitors.... yep all about the circuit.. just totally guessing it's one of these. \$\endgroup\$
    – Spoon
    Feb 29, 2016 at 12:54
  • \$\begingroup\$ oke. thank you for you answer guys. I only use a 2 resistor each op amp. That is why I said my circuit ok. But I will change my resistor to other one, and recheck my soldering, my input. For the load, I havent put any load. I just tested the voltage. \$\endgroup\$
    – ucon89
    Feb 29, 2016 at 13:31
  • 1
    \$\begingroup\$ Without the schematic, how can we help you. "I only use a 2 resistor each op amp. That is why I said my circuit ok." There are a whole lot of ways to attach two resistors to an op-amp and make a circuit that doesn't work. \$\endgroup\$
    – uint128_t
    Feb 29, 2016 at 15:16
  • \$\begingroup\$ I already update with my circuit. What kind of possibility due of this weird behavior? \$\endgroup\$
    – ucon89
    Mar 1, 2016 at 1:35

1 Answer 1


The op-amps on an LM324 chip are essentially identical to each other (differences would be in mV) and you've swapped the chip so your circuit implementation must be faulty. So maybe you have a wrong or defective resistor or some conductive stuff on the PCB or you have a capacitor on the output that you think doesn't matter - whatever it is is something you have done.


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