Dave Vanee wrote:
>
> Hello,
> I'm building a fuel injector flow bench and am having trouble finding out
> how I should power the fuel pump and injector.  The voltage has to be made
> to vary between 1.5V and 16V (roughly).  Also, I think the pump and
> injector will need anywhere from 4A to 8A (I've been looking for a 10A
> method to be sure).
>
> Can anyone suggest a regulator or device which I might use?  All I've
> found that might help is this part: LT1270ACT-ND from Digikey.  The main
> problem is that it's a little costly.  I know someone else who has done a
> similar project, and they used two car batteries (I'd like to use a
> standard wall-socket as the source).


Hi Dave, I have a great way of making these and
do it all the time for friends who need high
current variable supplies and cheap... (you know
how expensive these are to buy??)

I go the local electrical scrapyard, find any old
power supplies or equipment that has big heatsinks
full of TO-3 transistors. These were VERY common
back in the 70's and 80's (linear days) and are
all very obsolete now and sold for scrap metal.
If you get lucky you might even get case, fan,
transfomer, fuse/switch etc. I often get a 200w
or 300w units etc complete for about $10 US.

Even if you just get the heatsinks and transistors
that is ok. You can get a 18v 17A toroid from
Digikey etc for about $40. About $25 for a 200w
toroid if you find one with the right ratings.

You can make a very effective linear adjustible
high current supply just using a cheap regulator
like a LM317 to drive the big pass transistors
on the heatsink. Find any circuit on the net that
shows a LM317 driving an "external" series
transistor. :o)
-Roman

PS. Most electronics shops sell cheap 10A or 20A
panel meters, this is a VERY handy addition to
the supply. And a voltmeter obviously.

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