Power Supply (toroid) help

[pollypocket]

Greetings;

I have a question regarding toroid transformers in a power supply for an amp.

I have a dual power supply using a pair of 800VA toroid transformers. Is there any problem with stacking the toroids on top of each other? Is there any concern with running a bolt through the middle of the toroids to secure them?

If I remember high school physics, when you insert a steel core in to the middle of an energized coil, it has an effect on both the coil and the core.

Or am I worrying needlessly?

thanks,

Paul

[richie00boy]

You can stack them but you will need an insulating pad between each one, and you must be careful not to let the bolt end touch the top of the chassis or a shorted turn is formed.

[pollypocket]

Richie;

Thanks for the reply.

The toroids are wrapped in plastic covering so they are insulated. The hold down bolt doesn't touch the cover, but it is bolted through the bottom of the case, which is grounded.

Paul

[AndrewT]

Hi,
the bolt usually secures a steel dished washer to hold the transformer in place.

I habitually cover both the washer and bolt head in two layers of insulating tape to ensure no accidental shorting of the bolt/washer to chassis.

The coil you refer needs to be wound around the iron core for the effect you describe.

The toroid wire is wound around the transformer core not around your bolt. Therefore no interaction happens.

[pollypocket]

Andrew;

Thanks, the light has come on. There is a steel disk to anchor the toroids. I left the one in between also to ensure it didn't shift.

I am still not clear on why you insulate the bolt at the top end if the other end in secured to the chassis? Is having the bolt in the chassis a concern?

thanks,

Paul

[mpmarino]

Polly,

Before you go any further read this thread where I made a fool of myself I learned what a shorted turn is that day. start at post ~8.

thread

[AndrewT]

Hi,

....to ensure no accidental shorting....

[pollypocket]

Marc;

Thank you for the thread...I understand completely now. I was getting hung up in the nomenclature.

I guess I need to find some nylon bolts/rod.

thanks guys,

Paul

[richie00boy]

DO NOT use nylon it will loosen over time.

There is nothing wrong with a normal steel bolt you don't even need any additional insualation. Just make sure there is clearance from the lid to the top of the bolt. It's ok for the head of the bolt to be in contact with the chassis, just not both ends.

[pollypocket]

Richie

Good point.

Thanks for the advice.

Paul