Ways to test a transformer - Electronic Circuits Projects Diagrams Free

Nostrafus · 27th June 2003, 03:33 AM

Aiight, I got this circuit I want to duplicate (it broke, was made poorly, and want to remake it with better components) and the transformer has only one marking on it, no serial or anything, and I'm afraid to strip it to pieces to look for it as I may not be able to rewind it and get the same performance for testing what kind it is.

Anyone got any ideas.

Marking is 18, can't tell if it's on primary or secondary as the windings are covered by shrink plastic.

Nostrafus · 27th June 2003, 03:37 AM

I was thinking hooking up a AA to the primary windings and then use a multimeter on the secondary and getting the ratio so I can figure out what it is.

mattg2k4 · 27th June 2003, 04:02 AM

Holding a AA to a transformer won't give you much to work with, a single up and down cycle of the voltage then the AA is applied and removed. I don't know if a multimeter will be able to measure this, but if it can it will only appear for a second and you might not catch it.

A 555 square wave generator could be hooked up say at 60 Hz (seeing as how that's the frequency of mains here), or if you're feeling fancy, you could turn that into a sine wave generator. Or just hook it up to mains. That might be a bit risky, since mains is mains, but it would certainly be easy.

stevez · 27th June 2003, 11:05 AM

I agree with avoiding connecting to the mains - too dangerous. You could take a doorbell transformer to drop the mains voltage to something safe ( the sine wave generator is best but not sure you have access to one). Then take a small light bulb (bulb, not LED) with a voltage at least that of the doorbell transformer that will act as a series resistor to limit the current - and apply voltage to one side momentarily and measure the voltage across the transformer leads on the input - then on the output. The ratio of the voltages should tell you what you want to know. What you won't know is how much current the windings can take. There is a crude rule of thumb for total power rating of a transformer based on the cross sectional area of the core but I don't have access to my manual at the moment.

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27th June 2003, 03:33 AM	(permalink)
Nostrafus	Ways to test a transformer Aiight, I got this circuit I want to duplicate (it broke, was made poorly, and want to remake it with better components) and the transformer has only one marking on it, no serial or anything, and I'm afraid to strip it to pieces to look for it as I may not be able to rewind it and get the same performance for testing what kind it is. Anyone got any ideas. Marking is 18, can't tell if it's on primary or secondary as the windings are covered by shrink plastic.

27th June 2003, 03:37 AM	(permalink)
Nostrafus	I was thinking hooking up a AA to the primary windings and then use a multimeter on the secondary and getting the ratio so I can figure out what it is.

27th June 2003, 04:02 AM	(permalink)
mattg2k4	Holding a AA to a transformer won't give you much to work with, a single up and down cycle of the voltage then the AA is applied and removed. I don't know if a multimeter will be able to measure this, but if it can it will only appear for a second and you might not catch it. A 555 square wave generator could be hooked up say at 60 Hz (seeing as how that's the frequency of mains here), or if you're feeling fancy, you could turn that into a sine wave generator. Or just hook it up to mains. That might be a bit risky, since mains is mains, but it would certainly be easy.

27th June 2003, 11:05 AM	(permalink)
stevez	I agree with avoiding connecting to the mains - too dangerous. You could take a doorbell transformer to drop the mains voltage to something safe ( the sine wave generator is best but not sure you have access to one). Then take a small light bulb (bulb, not LED) with a voltage at least that of the doorbell transformer that will act as a series resistor to limit the current - and apply voltage to one side momentarily and measure the voltage across the transformer leads on the input - then on the output. The ratio of the voltages should tell you what you want to know. What you won't know is how much current the windings can take. There is a crude rule of thumb for total power rating of a transformer based on the cross sectional area of the core but I don't have access to my manual at the moment. __________________ stevez