Electronics > Projects, Designs, and Technical Stuff
Quiet transformers
Rachie5272:
My latest project requires custom transformers, and we're currently using standard E-cores. It works fine, but it buzzes a bit louder than I would like. It's probably silly, but I'd like to make things a bit nicer with a quiet transformer. It's an audio transformer roughly 1cm cubed, being fed with square pulses.
Are there any manufacturing techniques to prevent vibrations, and thus noise? Maybe dipping the whole thing in epoxy?
schmitt trigger:
Did you actually built the transformer?
If so......
EI laminations indeed rattle, if they are not impregnated with the heavy varnish specifically designed for that purpose.
If it is a commercial transformer you purchased and is varnished and still rattles, you may be over driving it.
thermistor-guy:
--- Quote from: Rachie5272 on April 22, 2020, 12:51:00 am ---...Are there any manufacturing techniques to prevent vibrations, and thus noise? Maybe dipping the whole thing in epoxy?
--- End quote ---
For telecom applications, we used to glue the cores and the windings, to stop them from moving. That was enough to meet acoustic emissions spec of telephone exchange equipment.
There are still some potential acoustic emissions from magnetorestrictive effects on the core. I have no experience with this; maybe a sound-deadening mounting of the transformer will help. You may not need it.
So treat the cores first, then the windings, then the mounting.
coromonadalix:
better go with toroids xformers
but in your case yes dipping it in epoxy should do the trick
CatalinaWOW:
Epoxy covers a lot of sins. I can't recommend a special type, but it will have to be a slow cure, low viscosity resin to wick into the cores and provide the needed sound control. You might find it easier to do some research on the varnish which was traditionally used and may well still be available. Tar has also been used for this in the long ago past. It works but is messy, tends to drip out if you get the core warm and smells bad. Not recommended.
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