In article , William G Darby wrote:

"Keith Marshall" wrote in message
...
The first is as per the subject line: What would I need to construct a
PSU
for my 18 volt cordless tools. My batteries just will not keep up. ( I
was
thinking only of a transformer and a full wave rectifier, and wondered
if
I
needed something special to allow the variable speed function to work)

Ideally you would need a transformer (probably a pretty hefty one!), a
rectifier, a couple of capacitors and a regulator plus a few other items
such as a case, etc. You might get by with something simpler but it
probably wouldn't be a very good idea.

But if you're going to go to the trouble of powering it with A/C why not
just buy an A/C drill? Here's one that looks comparable to yours for
[....]

Thanks Keith
No, I am in pretty good shape when it comes to AC drills. The thing is
that the darn batteries cost so much that it's not worth the cost to keep
the tools on the road. But the only sawsall I own is an 18V dewalt and it
seems a shame not to be able to use it while I have on hand all the
components to put together a DC power supply for it.

if you just want the power not the portability, you have had suggestions,
but if it were me i would kludge an avail battery onto it. make some
kind of terminal adapter for the cheapest new or replacement battery
avail. it couldn't be any more difficult or look any more cobbled up.

--Loren