RadioBanter - View Single Post

January 4th 05, 12:58 AM

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