I have been working on an Arduino DC programmable power supply using:

  • MPC4725 (Digital to Analog Converter)
  • LM358 (Operational Amplifiers)
  • IRFZ44N (Mosfet)

Wanting to add a current limiter feature, I found a circuit pretty interesting described here:


However, I cannot understand the point of having the 10 kOhms resistor at the non inverting input... Do you have any ideas?

Other question is about the 100nF capacitor with 1kOhm resistor. It seems to me that it is some kind of pass band filter... Do you agree with that?

enter image description here

Thank you for your help

  • \$\begingroup\$ Check this one electronics-tutorials.ws/opamp/opamp_6.html \$\endgroup\$ – Daniel P Feb 19 '18 at 1:30
  • \$\begingroup\$ Thank you Daniel. This tutorial is well written and it helps out about the capacitor. What about this 10kOms resistor? I could not find any similar circuits. On my point of view, it is useless since the impedance is already very high on the non inverting input... But I would appreciate to get another point of view from someone with more experience! :) \$\endgroup\$ – Lucas A Feb 20 '18 at 8:35
  • \$\begingroup\$ Well the 10k resistor is a mystery to me. If I had designed the circuited I wouldn't have put that resistor. The input current is in the order of nA so the voltage drop over that resistor wouldn't be measurable with a common multimeter. \$\endgroup\$ – Daniel P Feb 20 '18 at 17:06

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