Hi,

I want to buy one of those hobbiest PC Osilliscope / Logger / Frequeny Analyser etc. However the oscilliscope max voltage range is 0-20V. I want to use it to examine harmonics on the Mains AC (240VAC) line.

Can anyone recommend a good "low noise" transformer that will not introduce harmonics into the very signal I am trying to measure?

Also, How do I shift the the stepped down volatge into the 0-20V AC range ie not -10V / + 10V range that would come out the other end of the transformer?

Many Thanks

 

Preserving bandwidth with a transformer isn't easy.

I'd suggest something more akin to a voltage isolation module such as the one shown in the attachment.

You may prefer to do a more extensive search to find other options or manufacturers. Off-the-shelf availability may be an issue. I haven't investigated thoroughly.

http://www.lem.com.cn/docs/products/cv%203-1000.pdf

 

Your oscilloscope may be able to measure higher voltages with a x10 probe or more.

 

Your oscilloscope may be able to measure higher voltages with a x10 probe or more.

Check here, amongst other places. I'm not associated with them; I've just used some of their products and they work fine.

 

How about using a voltage divider consisting of two 1% resistors....]

Reference the reading to the neutral line (white) wire.

 

How about using a voltage divider consisting of two 1% resistors....]

Reference the reading to the neutral line (white) wire.

This is a cheap but not a good idea at all in your are not a proffesional because there is no isolation and a fault can be deadly.

 

Thanks everyone who replied. Very helpful.

 

I would buy a x100 scope probe. that will make my 20V scale 2000 Volts/cm.