On 2 Jan 2005 18:53:36 -0800, wrote:

I just had two powersupplies and ran the cables together so a simple
way of putting it would be that I have an amp, and i took the + from
both powersupplies, and put them to the + on the amp and the same with
the -. do you think it would work for me to get some bridge rectifiers
from radioshack? (25 amp bridge rectifier is $3.50 or something like
that,) get 2 of them and isolate each powersupply?

Go to your local auto supply store and get a reverse-polarity
two-battery isolator. Tell them that you are running a
positive-ground British RV or something exotic like that. These
devices exist but they have to be ordered from the warehouse. They
consist of two horse-size diodes mounted on a heat sink with nice
big screw terminals. There should be a clear hook-up diagram with
it. This will be cheaper and easier than buying the components and
manufacturing the device yourself.

Connect one P/S to one input, and the other P/S to the other input.
Connect the load (amps) to the output/common. Warning - if one
supply has a slightly greater output voltage than the other, that
one will pick up the whole load. Digital metering of each supply's
output and the load voltage (nominally 0.7 V below the supply
voltage) is important.

That's how I run my communications center, with a big marine
gel-cell battery floating on the DC bus (13.8 V). Haven't had a
problem in five years' continuous duty.

--
73 de K2ASP - Phil Kane

Even with diodes, it is often the case that one supply will hog all
the current while the other one loafs, as the output set points of
both would never be exactly the same. The easiest way to deal with
the problem is to hang a boat battery on one supply to float.

Unless you are going for the Neil Young sound, the average will be
lower than the peak, allowing the battery to absorb a lot of the peak
current with one supply operating quite efficiently.

It may be difficult to truly separate the two amps with their own
separate supply as this may lead to ground loop problems, but if you
can tie the grounds together, you might not.


Another approach would be to check out E-bay for a good clean used
integrated amp.

Jim


"Robert Kubichek" wrote in message
...
All you need is 2 25amp diodes and hook up so it looks like one
half of
a4 diode full wave bridge rectifier, or it looks like a 2 diode
full
wave bridge rectifier. The output is positive, and the input of
each
diode is the positive output from each power supply.

in + |
\
+ out
/
in + |

pos from power1 to diode | output tied to second diode output
common output is positive at amp/power1 + amp/power2
pos from power2 to diode | output tied to first diode output

I would still supply each amp separately, due to voltage
requirements.

Bob N9LVU

wrote:
I just had two powersupplies and ran the cables together so a
simple
way of putting it would be that I have an amp, and i took the +
from
both powersupplies, and put them to the + on the amp and the same
with
the -. do you think it would work for me to get some bridge
rectifiers
from radioshack? (25 amp bridge rectifier is $3.50 or something
like
that,) get 2 of them and isolate each powersupply?

Even with diodes, it is often the case that one supply will hog all
the current while the other one loafs, as the output set points of
both would never be exactly the same. The easiest way to deal with
the problem is to hang a boat battery on one supply to float.

Unless you are going for the Neil Young sound, the average will be
lower than the peak, allowing the battery to absorb a lot of the peak
current with one supply operating quite efficiently.

It may be difficult to truly separate the two amps with their own
separate supply as this may lead to ground loop problems, but if you
can tie the grounds together, you might not.


Another approach would be to check out E-bay for a good clean used
integrated amp.

Jim


"Robert Kubichek" wrote in message
...
All you need is 2 25amp diodes and hook up so it looks like one
half of
a4 diode full wave bridge rectifier, or it looks like a 2 diode
full
wave bridge rectifier. The output is positive, and the input of
each
diode is the positive output from each power supply.

in + |
\
+ out
/
in + |

pos from power1 to diode | output tied to second diode output
common output is positive at amp/power1 + amp/power2
pos from power2 to diode | output tied to first diode output

I would still supply each amp separately, due to voltage
requirements.

Bob N9LVU

wrote:
I just had two powersupplies and ran the cables together so a
simple
way of putting it would be that I have an amp, and i took the +
from
both powersupplies, and put them to the + on the amp and the same
with
the -. do you think it would work for me to get some bridge
rectifiers
from radioshack? (25 amp bridge rectifier is $3.50 or something
like
that,) get 2 of them and isolate each powersupply?