Smooth Cap Values

[chriscool]

This a bit off the topic of stomp boxes. I need to smooth out a half wave rectifier as much as possible. Wiring two 40V secondary center tapped X-formers in series to get 80V. When doing this I can only get one secondary to 80V, therefore the I am stuck with using a half wave rectifier. Can't afford $250 on an X-former from Hammond to the needed specs. Any help with figuring out what capacitor values I need to make the DC as smooth as possible would much of appreciation.

[PRR]

> what capacitor values I need to make the DC as smooth as possible

As much as you can afford.

The load-current also matters a lot.

Is there some specific level of smoothing which is acceptable?

I do not understand why you can not use a Bridge rectifier.

[chriscool]

I do plan to use a bridge rectifier but I still need to smooth the DC. Not sure what the load current will be. This power supply will be feeding a ICEpower500A amplifier amp module.

[PRR]

Page 9:
http://www.icepower.bang-olufsen.com/files/solutions/icepower500adata.pdf

> Wiring two 40V secondary center tapped X-formers in series to get 80V

80 volts AC will give 113 volts DC. The module is rated 85V absolute-MAX.

I hope you know what you are doing.

[DavenPaget]

I do plan to use a bridge rectifier but I still need to smooth the DC. Not sure what the load current will be. This power supply will be feeding a ICEpower500A amplifier amp module.

You don't really know what you are doing ... 113VDC will surely kill the amp .
You seriously only need 50V .

[iccaros]

This a bit off the topic of stomp boxes. I need to smooth out a half wave rectifier as much as possible. Wiring two 40V secondary center tapped X-formers in series to get 80V. When doing this I can only get one secondary to 80V, therefore the I am stuck with using a half wave rectifier. Can't afford $250 on an X-former from Hammond to the needed specs. Any help with figuring out what capacitor values I need to make the DC as smooth as possible would much of appreciation.

when you place two transformers in serries you have the two outside leads and the two that come together, which makes up your center tap. If you had center taps before you ignore them.

should look something like this


and the secondary looking like this

with the center jumper being your center tap.

[iccaros]

I do not know how many amps you need but Parts express has this 50v CT transformer (70.5v after full bridge rectification) for 6.95
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=129-084

[amptramp]

You can always satisfy your curiosity by simulating your circuit in the free power supply simulator:

http://www.duncanamps.com/psud2/index.html

As an approximation for the first cap in a filter,

CV = Q = IT where C is capacitance
                             V is voltage drop at each alternation (for a fullwave supply)
                             Q is charge
                              I is current
                             T is time period for a half cycle (for fullwave rectification)

If you are on a 60 Hz supply, the period is 16.666 msec and the half period is 8.333 msec.  So if you can tolerate a 1 volt drop on a 1 amp current drain, C becomes 8333 µF.  This is an approximation, but a useful one.                           

[DavenPaget]

He's better off with a 75V 600W SMPS for 4ohm loads and 80V 600W .
50W of dissapation in best case situations ( 4 ohm fully loaded ) for 4 ohm loads so 500+50W should be okay , but 600W to give it some slack .