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Power Supply Design Question - Click HERE for Original Thread
rjon17469
I have a question regarding the use of caps in a power supply:

I understand that caps are used in the power supply for both filtering and smoothing AC to DC. However, do the caps have to be connected from the rail to ground, or can they just be connected to both rails?

See attachment for schematics.

Thanks in advance!

Reece
Tensop
if you connect rail to rail you will need a capacitor with twice the voltage rating :)
rjon17469
quote:
Originally posted by Tensop
if you connect rail to rail you will need a capacitor with twice the voltage rating :)


Beyond that, it would work? To get similar results, would I also need double the capacitance?

Reece
ingvar ahlberg
No it will not work very good. The caps are filters, reservoirs and stabilizers to make the supply as stiff as possible. With the caps "floating" in respect to system ground the rails will start to fluctuate and it will affect signal and propably something will be destroyed.
rjon17469
quote:
Originally posted by ingvar ahlberg
No it will not work very good. The caps are filters, reservoirs and stabilizers to make the supply as stiff as possible. With the caps "floating" in respect to system ground the rails will start to fluctuate and it will affect signal and propably something will be destroyed.


Got it. Thanks!
IanAS
quote:
Originally posted by rjon17469
do the caps have to be connected from the rail to ground


Normally the ground IS the joint between the main res caps. Coupled to the centre tap of the Tx. of course.

In Dual Rail applications anyway.
jacco vermeulen
quote:
Originally posted by ingvar ahlberg
No it will not work very good

http://www.passlabs.com/np/MPA_PS_D0.pdf
byteboy
See:

cap discussion
quote:
http://www.passlabs.com/np/MPA_PS_D0.pdf

Good to know someone has some same idea like me......... :D

Not tried it yet though, would like to know if this realy works..........:scratch:
darkfenriz
I think it is OK to use only rail-to-rail caps in BRIDGE amp, isn't it?
otherwise I wouldn't use it
rjon17469
I'm not going to put the caps rail to rail.

Thanks for all your help. I was curious for the power supply design I was making.

Reece
djk
"I think it is OK to use only rail-to-rail caps in BRIDGE amp, isn't it?"

You got it, the 'X' amps are a bridge design.

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