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Attenuator for oscilloscope input stage

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Froginthewell

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I need an attenuator to scale down input voltage +-220V to 0-5V for my oscilloscope project. What would be the best way to do it? I have thought of using an opamp in inverting mode. But will LM324 accept 220V input?
 

Hoping not to be offensive, reading your question I think you are not familiar with electronics. An LM324 cannot accept 230Vac between its + and - input terminals.

If galvanic isolation is not of importance, a resistive voltage divider is used in most cases. However a general-purpose resistor cannot handle 220V safely. This means you need special resistors, or you need to use several resistors in series to share the voltage so that each resistor experiences a relatively low voltage. Note that the mains voltage also has transients into the kV range that damage your equipment.

If you only want to measure the 220V mains, you may use a non-encapsulated mains transformer and use the low voltage secondary as the output that goes to your oscilloscope project. You may wind your own secondary. Note that the peak voltage of 220V mains is around 310V.

Think twice (or more) before connecting some home brew circuit to the mains.
 

https://obrazki.elektroda.pl/48_1344479222.jpg

Sorry i didn't clearly posted before. I mean to say does above circuit works? I will be using higer wattage resistors.
Will zener and filters solve the problems of the transients?

If the attenuation of 1/100 is not suitable, I was thinkin of using resistor divider before inputting to the opamp.
 

You do not need an opamp to build an attenuator. Simply use two resistors ; but isolate your input via a suitable step down transformer
 

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