Copper Busbars in Aleph-X power supply - diyAudio
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Old 16th September 2003, 08:50 AM   #1
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Default Copper Busbars in Aleph-X power supply

Hi All,

I am planning the Power Supply in my upcoming Aleph-X project, and came across a dilemma. I own some lengths of heavy duty copper busbar, approx 40mm x 6mm cross section, which I have been saving for this project. I want to use them to move the Power supply currents around, from the rectifers to the filter caps to the output transistors. After all, it is widely accepted that this is a very good way of doing things, a lot of great amplifiers do this, or something similar (eg Pass Labs X series, Merk Levinson etc.)
However, in the XA200 amplifier, and therefore in my upcoming Aleph-X, it has a CRCRC filter, with the R's approx. 0.06 ohms. (From the XA200 8amp bias, with around 1volt drop across the R's, Anyway numbers aren't important in this question).
My question is, is it worthwhile using these massive copper busbars with ultra low resistance, if I'm going to insert a (relatively) high resistance in the circuit. Wouldn't I be better off using relatively small wiring, that simply handles the bias current?


Adrian
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Old 16th September 2003, 09:03 AM   #2
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I would say that doing something like this AFTER filter caps is probably worthwhile, but i you don't need the thickness you are referring to. I have done somthing similar using sheets of Cu right on top of one another (with appropriate holes and spacers) to get ultra-low impedance to the load. The setup is 9 units of capactitors (phase to phase in my situation), and the sheets are about 15*15cm. I think this would be fairly ideal.

The problem with bus-bars is - how do you connect to them reliably and with low impedance? I guess you could put all the caps in a line and just screw right through them - but I am pretty sure that won't get you as far as the sheets.

It would look cool. though!

Back to your question: After caps you should have low impedance. Before caps, it does not really matter all that much. Some inductance (or indeed some of your resistance) will probably do more good than harm.

Petter
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Old 16th September 2003, 12:46 PM   #3
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it may look cool -- but if it's accessible you may want to put some heat shrink tubing on the copper so someone doesn't use it as a handle.

the big Trygon (2kW) supplies I have use copper bar, copper braid and copper straps -- even looks as if they used some copper roofing sheathing, here's an example:
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Old 16th September 2003, 08:06 PM   #4
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Thanks for the input.

I suppose the other place I could use it are the output rails, and also for mounting the output transistors on, which then goes onto the heatsinks

Adrian
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Old 16th September 2003, 09:09 PM   #5
eLarson is offline eLarson  United States
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You could use them for the output rails, but then if the power is
ultimately coming from a lesser conductor, that wouldn't help you
much either, except in "looks cool" factor.

eL
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Old 17th September 2003, 10:43 AM   #6
grataku is offline grataku  United States
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I veemently disagree with the last post. There are a number of issues due to the high currents of the X circuit for which Cu bar are just about perfect, I won't go into details right now, build an AX and you will see. 6mm Cu bars maybe a little excessive but they do wonders for the grounds, whether you use single or dual rectifier bridge. I thought I was overdoing it but it ended up being just right. You can pretty easily engineer a way to use them for the +\- rails as well with the thermistor.
If you are going to use screw type capacitors you are probably going to need longer screws.
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Old 18th September 2003, 01:01 AM   #7
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I thinks the busbars look cool and are a cheap and effective way to tie things together. I had bought some 1/16"(1.6 mm) brass cut to my specifications at Metal Supermarkets (http://www.metalsupermarkets.com) for $4. Have a look at my pic.

Click the image to open in full size.

regards,
Dan
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Old 18th September 2003, 03:38 AM   #8
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I say go for it.
As an acquaintence used to say,"If some is good, then more is better, and too much is just enough!"

Grey
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Old 18th September 2003, 04:18 AM   #9
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I showed a pic of my copper buss bars in another thread...basically I buy 1"X1/4" from the scrap dealer and get 3 ft pieces for 10 dollars......I then machine/cut to my design

Cheers!!The DIRT®
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Old 19th September 2003, 12:01 AM   #10
eLarson is offline eLarson  United States
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Quote:
Originally posted by grataku
I veemently disagree with the last post.
Had I stated it with the sense of logic reversed "you'd be better off using a copper buss bar for BOTH the power AND the outputs" would that have made you a little less, er, vehement?

Erik
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