How hot is too hot to subject an output transformer to? I read that the pouring epoxy hits 200 degrees, is that too hot?
I was thinking it might be interesting to make a form and end up with a nice smooth black covering on a toroidal.
Since my outputs never get warm it generating heat in use shouldn't be a problem but the heat from the chemical reaction of the epoxy could be.
I was thinking it might be interesting to make a form and end up with a nice smooth black covering on a toroidal.
Since my outputs never get warm it generating heat in use shouldn't be a problem but the heat from the chemical reaction of the epoxy could be.
The problem with coating a toroid tfmr in epoxy is that the tfmr cannot dissipate heat as well, toroid's get hot, if your not careful an epoxy covered toroid could have an insulation breakdown. In amp building that uses a toroid or any tfmr really, a good air flow through the core and around the tfmr is desired to keep things cool The other issue is if at some point in the future a winding fails you can't easily dismantle the toroid to rewind it, which means a job that could take an hour or two will take a lot longer. If a toroid can be re-wound (an easy job on a low voltage high current secondary winding) it saves money, better that than chucking away the whole thing and buying another.
Andy.
Andy.
My output transformers haven't ever gotten above room temp but I run low power amps at generally low volume levels. I'll run the toroids before I do anything to them so I'll know.
At $70 new I can't imagine rewinding one, but I'm just not that DIY.
But, that said, those are all great points to include in a thread that may be read by someone else wanting to do it.
At $70 new I can't imagine rewinding one, but I'm just not that DIY.
But, that said, those are all great points to include in a thread that may be read by someone else wanting to do it.
The Toroidy OPT's are only potted in the center doughnut hole, not the whole thing. That seems like a good compromise to me. They come beautifully potted only in the center hole with what appears to be a pretty hard compound.
It makes sense for power transformers if only to make them silent. Just use very slow curing epoxy meant to be used for transformers. Let it cure for days in a well ventilated room preferably a barn or separate hobby room. The toroid wil be silent but you'll have to derate its maximum output power. I never went as far to drill ventilation holes in the mounting plate but at least I thought about it 🙂 For output transformers it makes less sense.
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Just an option to change the appearance other than covers.
Some different colors of epoxy and different shape options.
I doubt I'd do a power transformer with it.
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I think it is a great idea, but more for vibration dampening, like on Duelund Inductors. Most likely snake oil, but I always wanted to try it on my foil inductors.
Only a large quantity of fast cure epoxy will get hot. The slow cure stuff you won’t even notice.
Is that 200 degrees C or F? Do you know what the wire (especially its insulation) is rated at? It might be only 100 C or 125 C, probably whatever the transformer overall is rated at. Others' suggestion of slower curing epoxy sounds good.
For an output transformer, I can imagine an audio signal causing a bit of loose winding to vibrate, and that causing a small amount of distortion. Epoxy would surely fix this.