beerbarrel wrote:

Anyone have a source for a schematic for a 12v around 20 to 30 amp
power supply that makes use of a full wave rectifier? I've found quite
a few for a bridge rectifier but I'm not really sure how to mod them
to use a full wave rectifier. I have a nice 32v 30 amp center tapped
at 16v transformer that I would like to make use of.

Thanks...

You can use half of your bridge with this transformer to produce
something like 22 volts DC at the filter cap. Connect each end ot the
secondary to one of the AC inputs ot the bridge and connect the cap
and load between one of the DC connections of the bridge and the
center tap. If you use the + terminal of the bridge, it will be the
positive output. If you use the - terminal of the bridge, the center
tap will be the positive output.

The bridges will handle a bit more current than they are rated for,
because only two of the 4 rectifiers will be getting hot. They will
certainly need a heat sink for anything like 20 amperes out, though.

After you get that working and running a couple 12 volt headlights in
series (at least), you can start thinking about how to regulate this
down to 12 volts.

--
John Popelish

"beerbarrel" wrote in message
...
Anyone have a source for a schematic for a 12v around 20 to 30 amp
power supply that makes use of a full wave rectifier? I've found quite
a few for a bridge rectifier but I'm not really sure how to mod them
to use a full wave rectifier. I have a nice 32v 30 amp center tapped
at 16v transformer that I would like to make use of.

Are you mixing things together here?

There are full wave bridges that use a ct transformer and half wave bridges
that use non-ct transformers.

I know of no distiction between bridge rectifiers and full wave rectifiers
other than there can be full wave or half wave rectifiers and there is
usually a disctinction between encapsulated rectifier bridges and ones built
of discrete diodes and resisters.

After running a 32v ct transformer thru a full wave bridge you are going to
have way too much voltage for regulating down to 12v unless you enjoy the
extra heat.

Sounds like you intend to make a linear power supply, what sort of regulator
and pass transitors do you have in mind?
thanks, John.

Anyone have a source for a schematic for a 12v around 20 to 30 amp
power supply that makes use of a full wave rectifier? I've found quite
a few for a bridge rectifier but I'm not really sure how to mod them
to use a full wave rectifier.

Hi, Bridge rectifiers are full wave. Sounds like you want a full wave center
tap arrangment. These are very common, surprised you could not find a
schematic.
With a 32 volt center tapped xfmr, connect the center tap to common and
attach 2 rather large diodes to the other two transformer leads, and common
their anodes. You now have an unfiltered 22.6 volt full wave DC power supply.
Xfmr CT is negative, and the diode anodes are positive.
To get to a 12 VDC regulated supply add sufficient filter capacitors, and
regulator devices. A 12 volt 20 amp linear power supply requires heat sinks on
the solid state devices. I use about 50,000mfd filtering on mine, and a 200
volt 50 amp darlington transistor, as the series pass transistor regulator. I
used them because that is what I had on hand. The final design of your
regulated supply will depend on a number of factors.
73 Gary N4AST

On 09 Jan 2005 23:21:57 GMT, (JGBOYLES) wrote:

With a 32 volt center tapped xfmr, connect the center tap to common and
attach 2 rather large diodes to the other two transformer leads, and common
their anodes. You now have an unfiltered 22.6 volt full wave DC power supply.
Xfmr CT is negative, and the diode anodes are positive.

You have the rectifiers connected the wrong way to get a positive
output voltage. In half wave rectifiers, two diode CT full wave
rectifiers and in bridge rectifiers, the cathodes are always connected
to the _positive_ capacitor terminal.

Paul OH3LWR

You have the rectifiers connected the wrong way to get a positive
output voltage.

You are right Paul, thanks for pointing that out. Been too long since I
thought about anodes and cathodes on solid state rectifiers. I just look for
the band or the diode symbol on the the device and hook it up.
73 Gary N4AST

This is probably the thing for you.

http://www.qsl.net/yo5ofh/projects/power_supply.gif

Geir

"beerbarrel" wrote in message
...
Anyone have a source for a schematic for a 12v around 20 to 30 amp
power supply that makes use of a full wave rectifier? I've found quite
a few for a bridge rectifier but I'm not really sure how to mod them
to use a full wave rectifier. I have a nice 32v 30 amp center tapped
at 16v transformer that I would like to make use of.

Thanks...