At 01:24 20-08-98 +0100, you wrote:
>> So, does anyone make a box where you can set it for whatever voltage you
>> want from, say, 1vdc to 50vdc or something, with some way of hooking up
>
>What you want is called a 'bench power supply' and it's a common piece of
>electronic test equipment. The one I have does 0-30V (continuously
>variable) with a maximum output current of 10A. And you can set a current
>limit, so that if your device takes more than, say, 0.5A, the PSU will
>shut down, protecting the device. The output is on a couple of
>terminals/binding posts, so you can link up just about anything to it.
>
>The problem is the price. The one I have, as a kit, is about \pounds
>250.00 (!). There are cheaper ones (I've seen one for \pounds 60.00, I
--snip--
>Aha... That's the problem. They are _not_ cheap. You may find one of the
>Heathkit ones at a radio rally - I bought a non-working 0-50V, 1A
>Heathkit PSU at a rally for \pounds 5.00. Fixing it involved replacing
>the power-on lamp, which is a dropping resistor for the regulator as well.
Exactly Tony! Often at hamfests, or radio rallies in UK, one can find very
capable power supplies for quite reasonable prices. A common expression for
the type of variable PS we're talking about is " lab-type power supply" as
they are usually used in electronics labs or repair shops as a rather
flexible pieces of bench equipment.
I've got several extra rack mount power supplies at the old house I must
sell off as I don't have the same amount of space at the new house. Maybe I
should offer them to the list here in case anyone should need one for their
workbench to do just what has been discussed in this thread or whatever.
Gotta pull them out of the pile first though. Two types: one type is 0-36
volts DC at (IIRC) 5 or 6 amps and the other units are dual 0-18 VDC at 1.5
amps. Dual here meaning two separate identical PS's in one unit. Great for
those who need both + and - voltages in their application or simply two of
the same polarity or just on PS alone.
Tony's description (in previous msg) of how to design a simple linear power
supply and select the appropriate parts to replace the missing unit is
right on target.
Even though the description gives all that one needs to construct a PS, if
one is still shy about actually constructing it (lack of such experience)
perhaps a friend who is an experienced amateur radio operator or
electronics repair person could either build it or be at your elbow to
guide you through the construction. I've lent guidance often at work in
training a beginning technician or at home with friends who wanted to learn
how to swing a soldering iron. My wife and a few years later, my son are
next in line for this!
Incidentally, components for building such a PS can be found fairly readily
(and sometimes really cheaply) at a hamfest especially the larger hamfests
around larger towns. DigiKey is a rather good mailorder supplier of parts
too, for example. I buy ribbon cables from them for the oddball types I
need (that are not typical PC-types).
Regards,
Chris
-- --
Christian Fandt, Electronic/Electrical Historian
Jamestown, NY USA
Member of Antique Wireless Association
URL:
http://www.ggw.org/freenet/a/awa/
Received on Wed Aug 19 1998 - 20:45:31 BST