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I have a DC / DC converter in the + -12V output connected to the comparator's power pins. A square wave of 1 kHz is applied to one of the inputs of the comparator.

The output of the comparator should be in the form of a square wave, oscillating in the range of + -12V.

When connecting the multimeter to the output of the comparator, I see a value of -12V. When I switch to the frequency measurement mode, I see 999.6Hz, which approximately approaches 1kHz.

It’s not very clear to me how a multimeter can measure the voltage of a PWM signal. Why does he give out exactly negative voltage? Does he make a specific selection?

Delta
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    Please add in a schematic. There's a CircuitLab button on the editor toolbar. Use "Save and Insert" and an editable schematic will be saved in your question. Is the squarewave + only or + and -? What is the duty cycle (% on-time) of your squarewave? – Transistor Apr 01 '20 at 06:47
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    Cheap Multimeter are only able to measure sinus and dc signals. You have to use RMS tagged Multimeters to measure individual signals and they use sampling and calculations. – Findus Apr 01 '20 at 07:04
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    Possibly related: https://electronics.stackexchange.com/a/404964/35022 – MarkU Apr 01 '20 at 08:09
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    _"When connecting the multimeter to the output of the comparator"_ - Where are you connecting the other multimeter probe to? Which brand/model is it? – Bruce Abbott Apr 01 '20 at 08:42
  • Models: 1) Mastech MAS830L 2) OWON D35. Square wave 1kHz, 27% duty cycle. I connect directly to the output (track) of the comparator. I will send the scheme later. – Delta Apr 01 '20 at 09:36

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