EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: Mecanix on November 22, 2021, 02:12:50 am
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Looking to acquire isolation to safely measure AC switching with a scope for a SMPS design I'm experimenting with and came upon this product advertised as "Isolation Probe".
Are those actually optically isolated or mislabeled for a differential probe?
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That is a diff probe
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Right. Glad I've asked, thanks MasterTech.
I take that there is nothing remotely isolated in that tool?
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I take that there is nothing remotely isolated in that tool?
It provides isolation between the DUT and the oscilloscope.
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Presuming few 1kv rated current limiting resistors and a comparator (or more)? Sounds smokey!
I'll dig into this later on today, not familiar with those highVAC toys (thanks guys).
Got a feeling I just need an inexpensive 220V-to-220V transformer, have it canned in a small metal box and call it a day...
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Got a feeling I just need an inexpensive 220V-to-220V transformer, have it canned in a small metal box and call it a day...
It’s very unlikely a mains transformer designed for 50/60Hz operation will give suitable frequency response for SMPS operating in the 15-50KHz region.
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Presuming few 1kv rated current limiting resistors and a comparator (or more)? Sounds smokey!
I'll dig into this later on today, not familiar with those highVAC toys (thanks guys).
Dave has torn down a couple and yes that's more or less what goes into any "high voltage" differential probe, big divider (usually 4 megs each side for whatever reason) with an amplifier in the middle. I think the money is mostly in the compensation and fine tuning to give the whole thing a flat frequency response.
https://youtu.be/GOlgaEK2Hsk
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Interesting tool. Dave's vid confirmed what I've seen from another model spy shots I was looking at yesterday... just couldn't figure out the 'isolation' part. But after watching the vid and finally understanding all starts to make sense now. Regardless, spoke to a supplier (not the one of the pic, another one) and was told I needed both; the isolation transformer + diff probe kit (if done the correct/safe way is required, apparently). So I'll just gear up and cancel Friday's evening cinema and popcorn I guess.
Thanks guys, all good pointers I appreciate that. Man all that tooling... adds up quick just for a custom transformer and fet switching analysis. Hope I'll have the chance the re-use all of that stuff throughout the years...