Does anyone know if there is a Transformer Turns Ration Meter at the shop?
I have a guitar amp output transformer that is metering ok on my multimeter, but I wanted to make sure it was working correctly.
We have sig-gens and oscilloscopes… Can you excite it and measure the voltage without the purpose-built instrument?
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As long as I can slowly inch up the voltage I think I’ll be able to get what I need. I’m guessing I’ll need to get to about 30volts. Will those signal generators put out that much voltage?
No, I don’t believe they will produce 30V, but if your looking to determine turns ratio you don’t need anywhere near that much voltage.
Ok, it’s very possible that I don’t know what I’m doing. I’m basing needing 30V on this YouTube of a guitar tech checking a transformer.
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There is a 10 amp variac in the E lab. It has an ac outlet for its output - You don’t have worry about how to wire it up. Hook it up to the primary along w/ ac voltmeter and put another ac voltmeter on the secondary. Start the variac at 0 volts and dial your way up.
NO! I believe he is wanting to test an output transformer, not a power transformer. You should NOT use a variac with an output transformer.
To the OP, it would help if you describe what is wrong with your amp, its model, and what you are trying to test and why.
Good point. Don’t want to do that w/ an audio output transformer. Hmmmm…sig gen driving a pair of Apex pwr op amps in bridge configuration driving… Another project.
No need for a project. In the video the OP posted, he was using 30V because it produced 1V on the output and hence had an easy to calculate 30:1 voltage ratio. You can achieve the same thing with a signal generator and a two channel oscilliscope, which we have on each of the benches.
You connect channel 1 of the oscope to the primary and channel 2 of the oscope to the secondary. You then connect the signal generator to to the same connections on the primary that you connected the scope to. Do connect black to black on the gen and scope.
Set the sig gen to produce a 1kHz sine wave at say 10V peak to peak. Using the measure capability of the oscope measure the input signal and confirm you are seeing about 10V p2p. Now measure the p2p voltage of the secondary (channel 2 of the oscope).
Use this to calculate a ratio. If using the same tranformer as the guy in the video this should be 30:1. In other words your channel2 p2p should be about 1/3V. You can then use the rest of the math to calculate the input impedance of the transformer.
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Thanks! @wandrson That’s really what I needed to know. I’ve learned just enough about electronics to be dangerous 
but not enough to actually get work done
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