Power Supply Design Question

[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]

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]

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]

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]

No it will not work very good

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

 

[byteboy]

Idea ..........

See:

cap discussion

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

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

Not tried it yet though, would like to know if this realy works..........

 

[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.