How to do the best of connection in multi-CAP power supply

[ckwong99]

Hello there,

Can anyone tell me how do the best for the load connect to the DC source according to attached picture ?

This is the real wiring path in my power AMP DC supply and doesn't follow any regulation circuit.

CK

[pacificblue]

F-6, and don't forget small capacitors next to the load.

[ckwong99]

I am not sure what will be got, if F-1 be used.

[AndrewT]

Hi,
connect the load to D & 4, to minimse the inductance of the cabling.
Twist the cables from transformer to rectifier.
Twist the cables ab with 12
Twist the cables from smoothing caps to load.

Is the load an amplifier?
Then run the power supply traces right next to each other as much as possible and keep the power ground trace as near as possible.

Look at
http://www.diyaudio.com/forums/showt...60#post1890160

[ckwong99]

Yes, the load is power AMP.

I read the passage and understand how I connect them. Thanks.

[pacificblue]

Originally posted by AndrewT
connect the load to D & 4, to minimse the inductance of the cabling.

Is the additional impedance from D to E and 4 to 5 significant? And if so, would it not improve the filtering, when it is before the last pair of capacitors and therefore be a good thing? Or if it is bad, would the consequence be to connect the load right in the middle between C - D and 3 - 4? And should A and 1 also be connected to that same point?

According to capacitor manufacturers the right way to do it is disconnect 1 from 2, connect 1 to 5 and connect the load between E and 2, provided all capacitors are the same size.

[AndrewT]

my reasoning follows along the rCrC philosophy.
the first C in the group is the first C in the rCrC.
This is then followed by the longest (=highest impedance) route to the output.
The other three have two equal length wires and one zero length wires. This combination have the lowest impedance connections possible if one does not stack the caps on top of each other.

The r in this arrangement is tiny but it must have some effect and it cannot do any harm.
A reminder of what I said before. The first Cap in an RCRC or LCLC smoothing arrangement suffers high ripple.

[infinia]

You can hook it up pretty much as you've drawn it, but the key part is to tap the load off of the last cap as close to its terminals as possible. This will effectively keep Vripple lowest.

[pacificblue]

The question is, whether the r between the capacitors is significant. There were no values in the first post. The r could be so small that the set-up should be treated as parallel configuration of capacitors, i. e. rC instead of rCrC.

Originally posted by AndrewT
The first Cap in an RCRC or LCLC smoothing arrangement suffers high ripple.

And should therefore have low ESR, the lowest possible voltage rating and the biggest possible physical size. Plus sufficient airflow around it, which many people also like to forget.

[infinia]

You 2 guys like to split hairs. Just use wide traces to promote sharing caps esr, and the key part is to tap the load in the right place. You learn this stuff by building high performance SMPS.