Bill of Materials for Transformer

[CapnC]

I'm I missing anything?

55v @20 A, 5v @ 20A Transformer

1. 2 Toroidal Transformers 800VA ea
2. 2 Bridge Rectifiers (55v, 5v)
3. Filter Capacitors: 1 47,000 uF (55v), 2 120,000 uF (5v)
4. Toroidal Mounts
5. Capacitor Mounts
6. Bleeding Resistors
7. 10 AWG enamel wire (to wind 5v)
8. Input/Output Voltage Terminal
9. Enclosure

[ViperTX]

Wire to interconnect everything. I would add an input power switch and fuse holder.

[Al_The_Man]

I would include cooling fan, and a chunk of aluminum plate to mount the bridges on and possibly the Transformer, keep in mind all of these items, including the caps are de-rated once a certain temp. is reached. Also, if you use the typical centre-bolt & large disc mounting assy for the toroid, make sure no grounded object come in contact with the top disc or screw or you will have a shorted turn set up. (you will start to wonder why the txfr is heating up with no apparent load).
Al

[trilect]

You might also think about putting an inrush limiter wired in series with your input voltage. It looks like a ceramic capacitor and it has a high resistance for the first half second or 2 then it drops to almost nil.

This keeps your lights from dimming when you turn this thing on and makes your power switch last longer because it won't arc the switch as bad.

digikey has them 2 bucks or so.

[CapnC]

Hey Guys,

I will post an updated "Bill of Materials" shortly. I got the toroid transformers and unwound the wrapping and it appears the 40volt secondary is wound on top of the 17 volt secondary. I had planned on unwinding the 17 volt to get 5v, but I really don't want to unwind the 40v. So, I plan on creating a third secondary using 12 AWG wire (not magnet wire). Is it a bad idea to use insulated 12 AWG solid wire as a permanent secondary?

[Al_The_Man]

Originally Posted by CapnC Hey Guys, So, I plan on creating a third secondary using 12 AWG wire (not magnet wire). Is it a bad idea to use insulated 12 AWG solid wire as a permanent secondary?

It should not be a problem, the reason for magnet wire is the overall dia is less than other kinds of insulation, as long as you can get the turns on it should be OK, although ideally for maximum coupling, magnet wire would be the way to go.
A visit to your local motor re-winder might get some results just for a few feet you need.
Al

[ViperTX]

Only that it takes up more space and the insulation might not be rated for the temperature rise....use 105 C or above for temp rating.

[CapnC]

Updated Bill of Materials for Dual output powersupply 55V and 5v @ 30 amps

1. 2 800VA Toroidal Transformers
2. 2 Bridge Rectifiers
3. Filter Capacitors - 1 x 37,000uf
2 x 12,000uf
4. Toroidal Mounts
5. Capacitor Mounts
6. 12 AWG stranded wire/solid wire
7. 2 Fuse holder
8. Fuses
8. Inrush limiter
9. Enclosure w/Fans
10. Bleeding resistors 3 10k 5watt
11. Power Cord
12. Rocker switch
13.Quickconnect connectors
14.Ring Tongue Terminals

Is it okay to wrap back up the toroid with electric tape? Can it handle the heat? I just wrapped up a whole donut...very tedious work.

[trilect]

"Is it okay to wrap back up the toroid with electric tape? Can it handle the heat? I just wrapped up a whole donut...very tedious work."

I've never used electrical tape to wrap one so I can't answer for sure. I use mylar tape when I wind them for amplifiers and shield them with stainless steel to keep the noise out of my amplifer circuit. You won't need to shield yours though.

[CrocDundee]

How about the old way of wrapping the toroid with cotton tape ( you know, the stuff your mothers used to write your name on and sew into your coats and pants)..Then put it in a tin can filled with floor varnish overnight, then take it out and cook it for 24 hours..pretty good insulation I reckon.....

[Al_The_Man]

Originally Posted by trilect shield them with stainless steel to keep the noise out of my amplifer circuit. You won't need to shield yours though.

The benefit of Toriods is that there is virtually no radiated energy compared with the square stack txfr, when used with amplifier circuits, if you do shield, it is important not to completely cover the txfr if a centre bolt is used as a shorted turn condition is set up.
Al.

[ViperTX]

trilect,

Electrical tape will create a googy mess once it warms up...so avoid it. Maybe the heat resistant tape used to wrap car exhaust pipes...I'd check the local auto parts store.