sourcing out small transformers

bzhei · 25th January 2012, 06:21 AM

hi guys,

i'm working on an electronic crossovers and have replaced the op-amps in the audio section.

since the new op-amps were installed (lm4562), it is still working perfectly.

but i know the lm4562 draws current far more than the stock ones ba4558,ba4560, i want to upgrade the small transformer in the supply section.

however i tried searching the web but couldn't find any info on what they are specifically called and were to purchase them. they look like the one pictured below. the one labeled 3540100.

the diodes (1 zener, 1 1n4934) beneath it reads 25.7vdc before entering the transformer. then after the transformer, before entering the diode, it reads 13.7vac. can't read anything with my dvm set to DC. then after the diodes, i get the +/-15v for the op-amps.

where can i get one with higher rating, and what other specs should i be looking/be concerned with?

thanks

johansen · 25th January 2012, 08:16 AM

There's no reason to upgrade anything unless you're pulling enough current to burn that LT1072 out, and it will be the first to go, not the transformer.

bzhei · 25th January 2012, 04:25 PM

ok, thanks. when i had the ba4558 and ba4560, the supply pins read +/-15.17v. With the lm4562 in place, it dropped down to +/-14.96v

thanks for the heads up. but for future projects, can you lead me to a website where i can find more info about this small transformers? i wanted to at least get some knowledge about them.

thanks again.

johansen · 26th January 2012, 07:41 AM

Quote:

Originally Posted by bzhei

ok, thanks. when i had the ba4558 and ba4560, the supply pins read +/-15.17v. With the lm4562 in place, it dropped down to +/-14.96v

thanks for the heads up. but for future projects, can you lead me to a website where i can find more info about this small transformers? i wanted to at least get some knowledge about them.

thanks again.

That voltage drop is well within the normal voltage regulation of small flyback or forward converters, you might be able to pull it all the way down to 14 volts before you notice anything overheating.

As far as small ferrite transformers go, the fundamentals are unchanged. however due to the very small core you'll need a lot of turns and leakage inductance is rather high.

here's a link that might help you out.
2001 Magnetics Design Handbook - MAG100A

bzhei · 27th January 2012, 12:16 AM

ok johansen, noted everything. will be checking out the link.

thanks for all your help.

25th January 2012, 06:21 AM	#1
bzhei diyAudio Member Join Date: May 2011	sourcing out small transformers hi guys, i'm working on an electronic crossovers and have replaced the op-amps in the audio section. since the new op-amps were installed (lm4562), it is still working perfectly. but i know the lm4562 draws current far more than the stock ones ba4558,ba4560, i want to upgrade the small transformer in the supply section. however i tried searching the web but couldn't find any info on what they are specifically called and were to purchase them. they look like the one pictured below. the one labeled 3540100. the diodes (1 zener, 1 1n4934) beneath it reads 25.7vdc before entering the transformer. then after the transformer, before entering the diode, it reads 13.7vac. can't read anything with my dvm set to DC. then after the diodes, i get the +/-15v for the op-amps. where can i get one with higher rating, and what other specs should i be looking/be concerned with? thanks

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25th January 2012, 08:16 AM	#2
johansen diyAudio Member Join Date: Apr 2010 Location: seattle, wa	There's no reason to upgrade anything unless you're pulling enough current to burn that LT1072 out, and it will be the first to go, not the transformer.

25th January 2012, 04:25 PM	#3
bzhei diyAudio Member Join Date: May 2011	ok, thanks. when i had the ba4558 and ba4560, the supply pins read +/-15.17v. With the lm4562 in place, it dropped down to +/-14.96v thanks for the heads up. but for future projects, can you lead me to a website where i can find more info about this small transformers? i wanted to at least get some knowledge about them. thanks again.

27th January 2012, 12:16 AM	#5
bzhei diyAudio Member Join Date: May 2011	ok johansen, noted everything. will be checking out the link. thanks for all your help.

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