Electronics > Beginners
transformer testing (toroid)
jaunty:
--- Quote from: Jwillis on January 21, 2020, 05:18:24 am ---Taking an inductance measurement and comparing it to what the inductance should be is the most accurate. if the inductance is far to low for the size of coil on a core theirs a short.
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ok that's DEFINITELY useful thanks
tautech:
--- Quote from: jaunty on January 21, 2020, 04:22:45 am ---tautech : yeah i normally do that anyway - at least when powering up something i worked on extensively for the first time
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Good on you ! It's good simple insurance not to let the magic smoke out.
Still you must use some discretion as to when you can use a dim bulb tester as some SMPS preregs don't like them at all. Some later Phillips CRO's apparently also.
FYI here's a post I did some years back of my dim bulb tester:
--- Quote from: tautech on June 30, 2014, 01:15:58 am ---My Dim Bulb Tester
Just a incandescent bulb wired in series with the DUT, and good to have a small range of bulbs.
This one is switched SPST, but in countries without a polarized main plug I would recommend a double pole switch
As is evident it was knocked together at no cost in a dead PC ATX case, using the existing IEC mains socket and a few "bits and bobs".
On power-on the bulb should momentarily flash bright, then dim after inrush currents subside.(if all is well).
If the bulb remains bright and the bulb wattage is appropriate for the DUT then "Houston, we have/still have a problem. :'(
If you have a DUT that has emitted the magic smoke or continually blows fuses this can be indispensable.
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For a transformer like your one in question it helps to understand a little of how and why they are wound like they are and if all secondary windings are step down they'll naturally have less turns and be thicker wire, not that you can see them as they'll most likely be terminated onto tails. Still if they weren't identified the winding with the highest R will be the primary and other low R windings secondaries.
You need watch for tapped windings especially on the primary side like those for different mains voltages for international use.
Don't be scared of these things just apply the thing between your ears and a dollop of safe practice and have fun.
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