testing unknown transformers

cm961 · 9th January 2004, 02:46 AM

Hi guys,

I'm working on a studio monitor project and I have a wack of transformers I've pulled from all kinds of equipment. I plan on using toroids from Plitron in the final assembly but I wish to find some transformers suitable out of my surplus pile. Most are EI laminate type (the big, bulky, unshielded kind). I wish to test the transformers to find out their ratios and other characteristics. I'm a 4th year EE but we never really covered transformers (or anything else in the program for that matter...) and I don't really want to just plug them into the mains for fear of blowing a house fuse. Should I use a signal generator and power amplifier as an input signal? And what sort of signal level should I adjust it to?

Pete

roddyama · 9th January 2004, 03:09 AM

You need a variac.

sam9 · 9th January 2004, 04:56 AM

The voltages are easy enough to work out. It's the VA rating that always bugs me. That's based on how many amps the transformer can safely take which is a question of heat dissapation. I sdupose you could estimate roughly based on mass but that's likely to have a big margin or error. Testing to destruction is one way but not very satisfying.

9th January 2004, 02:46 AM	#1
cm961 diyAudio Member Join Date: Jun 2001 Location: Peterborough, Ontario	testing unknown transformers Hi guys, I'm working on a studio monitor project and I have a wack of transformers I've pulled from all kinds of equipment. I plan on using toroids from Plitron in the final assembly but I wish to find some transformers suitable out of my surplus pile. Most are EI laminate type (the big, bulky, unshielded kind). I wish to test the transformers to find out their ratios and other characteristics. I'm a 4th year EE but we never really covered transformers (or anything else in the program for that matter...) and I don't really want to just plug them into the mains for fear of blowing a house fuse. Should I use a signal generator and power amplifier as an input signal? And what sort of signal level should I adjust it to? Pete

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9th January 2004, 04:56 AM	#3
sam9 diyAudio Member Join Date: Jun 2002 Location: Left Coast	The voltages are easy enough to work out. It's the VA rating that always bugs me. That's based on how many amps the transformer can safely take which is a question of heat dissapation. I sdupose you could estimate roughly based on mass but that's likely to have a big margin or error. Testing to destruction is one way but not very satisfying.