Slimmy

[steve-o]

Well the party went well and everybody had a good time

[dnar]

Looking good. A tip with the toroidal, dont let the mounting bolt touch the top of the case.

[steve-o]

Thanks.

Interesting .. Why not let the bolt touch the top ? It's ground potential from the bottom (which is the same as the top) ..
(ok if that's a joke it's too late tonight and I'll get it in the morning .. lol)

[dnar]

If it touches, the case and mounting bolt becomes a shorted turn, causing higher consumption and inrush, possible failure of the primary winding.

A single shorted turn in a transformer is a big problem as in theory it tries to dissipate infinate current, although in reality this current is limited by core losses and dc winding resistance. In the case of a mechanical shorted turn the dc resistance is very low.

Primary current can easily exceed ratings with overheating and failure common.

[steve-o]

Hmm. I've never heard that before. Interesting. How would this bolt/chassis single-turn "circuit" be considered part of the secondary transformer windings, unless you are referring to the negative side power supply output being grounded to the chassis.

[dnar]

A shorted turn in either primary or secondary windings is the same. Consider a bolt/chassis turn as another secondary winding ( single turn) that is shorted.

This has nothing to do with ground reference or your secondary circuit. Imagine adding a single loop turn to your toroid, you have created another secondary. Now join the two ends, shorted turn! Its the same with the chassis if the bolt touches the lid only much lower resistance and more current.

http://www.tortech.com.au/mini.html

http://www.toroid.com/mounting_hardw...g_hardware.htm

[steve-o]

From the 2nd link:

Caution-If you choose to apply your own mounting solution, remember that it is important that our transformer be mounted in such a way that the mounting screw and the metal chassis will not form a closed loop through the center and thereby create a shorted turn on the transformer.

OK , good info. I don't remember that from the courses in college, but there's probably a lot I've forgotten since then, being an old fart .. Appreciate the info!
I see you know your electronics, Dnar, are you in the field?

[dnar]

From the 2nd link:



OK , good info. I don't remember that from the courses in college, but there's probably a lot I've forgotten since then, being an old fart .. Appreciate the info!
I see you know your electronics, Dnar, are you in the field?

Thanks from one old fart to another Soon to be fifty...

Electronics? It was my hobby from the age of 10. Worked my way through concert touring, running my own businesses, studio engineering, working in control and automation, now I am the Engineering manager for a global pro-audio brand. You can check me out on Linkedin. Wayne Osborn Engineering Manager.

[dnar]

Here is another good reference to the shorted turn scenario I speak of.

http://www.digikey.com.au/Web%20Expo...f?redirected=1

[steve-o]

More good info Dnar. Thx.. Impressive resume too. "Soon to be 50" ? Wow .. must be nice, young man ..
You work with audio? Cool. Are you familiar with Adobe Audition 3.0 or CS5.5? They're what I've got for home-recording (in addition to some other stuffs) Pro Tools would be cool to have but y'know .. can't have it all .. especially with lasers as one of the hobbies heh ..