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# High frequency voltage measurement with digital multimeter

#### electronium

##### Member
Hello, I hope you are doing well
Guys, because I don't have a scope, if I want to measure the high frequency voltage with digital multimeter dt830d and victorvc97 and multimeters from this group, the gate voltage of MOSFET or igbt or pwm base transistor doesn't show the high frequency and the display number toggles, it doesn't fixed.Is there a pre-circuit for this??
Please help, after the prop multimeter, it can measure the pwm high frequency voltage in the switching sources. I don't know what circuit and how it should be?!

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What frequency are you trying to measure?

What frequency are you trying to measure?
Switching frequency of power supplies...up to 100khz

Switching frequency of power supplies...up to 100khz
Assuming you want to measure the frequency (not the voltage) you can get a voltage to frequency (and frequency to voltage) conversion chip.

If, on the other hand, you want to measure the voltage - rectify the signal through a diode and into a capacitor (second leg connected to ground) and you'll get the peak voltage that you can measure as DC voltage.

Assuming you want to measure the frequency (not the voltage) you can get a voltage to frequency (and frequency to voltage) conversion chip.

If, on the other hand, you want to measure the voltage - rectify the signal through a diode and into a capacitor (second leg connected to ground) and you'll get the peak voltage that you can measure as DC voltage.
I did not understand what you said, can you draw the circuit for me?
At the same time, I want to get high frequency voltage

Something like this...

Known as a "peak detector" - this will show the highest positive voltage input to this circuit over the time you measure. Set your meter to DCV when measuring between nodes 0 and 2. The output voltage will be about 0.6V less than your actual input peak because of the diode voltage drop.

Something like this...
View attachment 143934
Known as a "peak detector" - this will show the highest positive voltage input to this circuit over the time you measure. Set your meter to DCV when measuring between nodes 0 and 2. The output voltage will be about 0.6V less than your actual input peak because of the diode voltage drop.
Now if the voltage is very high, for example 311v pwm
drain and gate If MOSFET is considered, can it be the same circuit?

Now, if the voltage is very high, for example 311v pwm, in this MOSFET, is this circuit the answer?
You'd need to check the rating of the meter you're using, diode, the capacitor and the wire.

Then you'll need to be careful to discharge the capacitor after each use as you'll have a high voltage discharge and a spark. You may want to use a high voltage transistor to do the discharge so you don't have bare wires - you definitely get a spark and pop some molten metal - wear goggles and gloves if you don't find a high-voltage resistor. Also, if you simply use a switch, it may not last for many measurements.

Also, consider using a smaller capacitor 0.001uF (1nF).

You'd need to check the rating of the meter you're using, diode, the capacitor and the wire.

Then you'll need to be careful to discharge the capacitor after each use as you'll have a high voltage discharge and a spark. You may want to use a high voltage transistor to do the discharge so you don't have bare wires - you definitely get a spark and pop some molten metal - wear goggles and gloves if you don't find a high-voltage resistor. Also, if you simply use a switch, it may not last for many measurements.

Also, consider using a smaller capacitor 0.001uF (1nF).
I will implement the circuit and report the result in this thread in the form of images and clips

Something like this...

Known as a "peak detector" - this will show the highest positive voltage input to this circuit over the time you measure. Set your meter to DCV when measuring between nodes 0 and 2. The output voltage will be about 0.6V less than your actual input peak because of the diode voltage drop.
Analysis and report of test results in the form of photos and videos

1k resistor

Fast diode es2j

Capacitor 104

pwm gate test point and MOSFET 2n60 hot ground ratio in standby mode atx 250w power

Video test and circuit analysis with atx power
Note: I plug in at minute 0:03 and unplug at minute 0:14.

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Sorry, I don't connect to Iranian web sites.

Sorry, I don't connect to Iranian web sites.
dear Engineer! The upload center server has changed

Note that for high frequency signals, normal rectifier diodes like 1N4000 series will not work well - you need a "Fast recovery" type.

A UF4007 or similar would be suitable. The diode also needs to be rated at greater than double the highest peak voltage you will ever measure.

(A 1N4007 can take 30uS to stop conducting after the polarity reverses, so they should not be used for frequencies all that far above 50/60Hz).

Note that for high frequency signals, normal rectifier diodes like 1N4000 series will not work well - you need a "Fast recovery" type.

A UF4007 or similar would be suitable. The diode also needs to be rated at greater than double the highest peak voltage you will ever measure.

(A 1N4007 can take 30uS to stop conducting after the polarity reverses, so they should not be used for frequencies all that far above 50/60Hz).
He said he is using the ES2J diode (2A, 600V, 35nSec)

He said he is using the ES2J diode (2A, 600V, 35nSec)
Sorry, missed that bit!

Why does the input of the circuit show the peak voltage of the city, which is 320v dc, but the output shows 34vdc?

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