I want to build a bench power supply, and am looking 'round the net for a
good circuit.

Requirements: 2 outputs, adjustable v, adjustable i, v & i meters (or
digits). Prefer 30v max, or similar. Preset v selections (5, 12, 15, etc.)
would be nice.

Here's one I found, complete with the designer's smiling face on each circuit
illustration:

http://members.shaw.ca/roma/supply-4.html

What's your favorite circuit? Features you like that I haven't mentioned?

Thanks,
--
Al, the usual

sez:

...$20, which is what I pay for bench supplies.

Where?
--
Al, the usual

"Usual Suspect" wrote in message
obal.net...
I want to build a bench power supply, and am looking 'round the net for a
good circuit.

Requirements: 2 outputs, adjustable v, adjustable i, v & i meters (or
digits). Prefer 30v max, or similar. Preset v selections (5, 12, 15, etc.)
would be nice.

Here's one I found, complete with the designer's smiling face on each circuit
illustration:

http://members.shaw.ca/roma/supply-4.html

What's your favorite circuit? Features you like that I haven't mentioned?

Thanks,
--
Al, the usual


Perhaps you should get a copy of the current issue (March 2007) of Nuts & Volts
magazine. It has a construction article that's just begging for you to look at
it. The article is "A Test Bench Power Supply". The power supply, as
presented, provides two 0-20V @ 1A supplies and one fixed +5V @ 1A supply. Your
other fixed supplies are easily added by using the appropriate power
transformers and regulators. The regulator circuits are trivial.

www.nutsvolts.com
They will send you a free copy to entice you to become a subscriber. (My own
subscription has been ongoing since 1/80)
--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

Some days you're the dog, some days the hydrant.

In article .net,
Usual Suspect wrote:
I want to build a bench power supply, and am looking 'round the net for
a good circuit.

While not wanting to put you off, unless you already have most of the
major parts it will cost you far more to make than to buy a ready made
one. Such is life these days.

--
*Two wrongs are only the beginning *

Dave Plowman London SW
To e-mail, change noise into sound.

Here is a simple one for 0-30V @ 3A with current limiting

http://www.electronics-lab.com/proje...003/index.html

If you read thru the forums you'll find a parts list and updated
schematic that expanded this to dual 0-30 @ 5A complete
with PCB's that can be downloaded.

Further reading will show how to add digital V and A meters.

Good luck

Kevin

On Mon, 05 Mar 2007 20:06:49 +0000, Usual Suspect wrote:

I want to build a bench power supply, and am looking 'round the net for a
good circuit.

Requirements: 2 outputs, adjustable v, adjustable i, v & i meters (or
digits). Prefer 30v max, or similar. Preset v selections (5, 12, 15, etc.)
would be nice.

Here's one I found, complete with the designer's smiling face on each
circuit illustration:

http://members.shaw.ca/roma/supply-4.html

What's your favorite circuit? Features you like that I haven't mentioned?


It looks like a lot of fun, actually. To make it really sexy, you should
check the LM317 data sheet, and modify this one to be adjustable down to
0. :-) A current limit wouldn't hurt, and I guess you can do whatever
metering you want to.

I do kinda like the idea of presets - I even already have a circuit
in mind for n latching circuits for n spst switches. :-)

Have Fun!
Rich

Usual Suspect wrote:
I want to build a bench power supply, and am looking 'round the net
for a good circuit.

Requirements: 2 outputs, adjustable v, adjustable i, v & i meters (or
digits). Prefer 30v max, or similar. Preset v selections (5, 12, 15,
etc.) would be nice.

ok as far as it goes but you need to specify a current, line regulation,
load regulation, curent limiting, crowbar protection,
switching or linear, and even line voltage. also voltage range i.e. 0-30
5 - 30 etc.


Here's one I found, complete with the designer's smiling face on each
circuit illustration:

http://members.shaw.ca/roma/supply-4.html

What's your favorite circuit? Features you like that I haven't
mentioned?

Thanks,

my favorite? that would be 7 or 8 200w or larger NPN transistors in parallel
with emitter resistors mounted on a huge heatsink driven by another 200 W
transistor powered by a very large transformer into matched 30A bridge
rectifiers.
the main filer cap is a very large "computer" cap (ok, if you are young
think of a "power stiffener" for car audio.)

the voltmeter is a large mirrored scale and "expanded" using switchable
precision zeners. i.e. 0-10, 10-20, 20 -30V
the ammeter is a matching large mirrored scale attached to a high current
meter shunt through a multi-turn calibration pot. the meter has diode
limiters to protect it from surges.

the supply can be driven from an internal or external reference. the
reference source is on a separate winding and is offset several volts below
common so as to achieve a zero volt output. for improved load regulation the
regulator references to the output terminals. voltage is controlled via a
multi-turn pot.

primarily intended for high current applications at 13.8 Vdc this unit was
result after many less robust supplies became shall we say... non
functional.

logon to http://www.electronicsforyou.com were u can find the variable
power supply circuits, or logon to http://www.vegakits.com there a
circuit which ur looking for

On Mar 5, 2:16 pm, Usual Suspect wrote:
sez:

...$20, which is what I pay for bench supplies.

Where?
--
Al, the usual

Electronics (ham) swap meets. Any used HP is fine. Some of the Lambda
late model supplies with digital readouts have problems, but the older
gear is good. None of mine have digital displays, but meters are
cheap. I even have one of the HP Harrison supplies, which are stone
age. Speak of the devil:
http://cgi.ebay.com/HP-HARRISON-6200...C-BENCH-POWER-
SUPPLY_W0QQitemZ330093581220QQihZ014QQcategoryZ582 86QQrdZ1QQcmdZViewItem
This this the Lamba that often has trouble:
http://cgi.ebay.com/ws/eBayISAPI.dll?
ViewItem&item=330094946204&ssPageName=MERC_VI_RUPX _Pr8_PcY_BID_Stores_IT&refitem=330093581220&itemco unt=8&refwidgetloc=active_view_item&usedrule1=UpSe ll_LogicX&refwidgettype=cross_promot_widget


Bench supplies are quite heavy. I'd sure hate to buy one on ebay
unless the seller double packs it. Still, I'd get a HP supply from
Ebay before building my own.

Speaking of supplies with digital readouts, I recall a chip I designed
that worked fine with any bench supply except those HP with the
readout. [I'd have to research to find the number.] It turns out HP
put in a nice soft start feature that was so "soft" it found a flaw in
my undervoltage lockout.

Who makes these? Most likely the Chinese, maybe Korean.

http://webtronics.stores.yahoo.net/dualout03x22.html

Anybody know the manufacturer?

Sparky

THERES RAJ, BLR sez:

http://www.electronicsforyou.com

You, sir, are a troll.

The site is nothing but one of those "faux" resource sites that crop up way
too often in Google results stating that they have [fill in whatever terms
you used in your Google search] at the right price. Sites like this must be
simply collecting hits, showing the numbers to potential advertisers, and
collecting $$.

If anybody has any other suggestion as to what purpose these
serious-waste-of-time sites serve, I'd be happy to hear.

FBt

Usual Suspect wrote in message
obal.net...
I want to build a bench power supply, and am looking 'round the net for a
good circuit.

Requirements: 2 outputs, adjustable v, adjustable i, v & i meters (or
digits). Prefer 30v max, or similar. Preset v selections (5, 12, 15, etc.)
would be nice.

Here's one I found, complete with the designer's smiling face on each
circuit
illustration:

http://members.shaw.ca/roma/supply-4.html

What's your favorite circuit? Features you like that I haven't mentioned?

Thanks,
--
Al, the usual


Assuming your 2 supplies are from isolated secondaries or separate mains
transformers and the outputs will parallel, then series/isolated
pair/parallel switch is easy to add to double volts or current range (single
rail).
If for repair or soak testing then something I would have had a use for is a
presettable current monitor that sounds a sounder if the current drain goes
above or below a settable amount from the initial free, ie below any current
limit , current drain, for instability/thermal/intermittant fault checks

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

I like this one:
http://www.wikihow.com/Convert-a-Com...b-Power-Supply

who doesn't have an old PC sitting around?

-Jeff

"Usual Suspect" wrote in message
obal.net...
I want to build a bench power supply, and am looking 'round the net for a
good circuit.

Requirements: 2 outputs, adjustable v, adjustable i, v & i meters (or
digits). Prefer 30v max, or similar. Preset v selections (5, 12, 15, etc.)
would be nice.

Here's one I found, complete with the designer's smiling face on each
circuit
illustration:

http://members.shaw.ca/roma/supply-4.html

What's your favorite circuit? Features you like that I haven't mentioned?

Thanks,
--
Al, the usual

cr500r sez:


http://www.wikihow.com/Convert-a-Com...o-a-Lab-Power-
Supp
ly

Aw, but they're *switchers*. A last resort for a bench supply, imho.
--
Al, the usual

They can be a bit noisy (understatement), but PC supplies are shielded, the
regulation is usually really good, and the amperage is great, as well as the
efficiency compared to linear.
It all depends on how much radiated noise you can accept, you can always
filter the wires coming out of it.

"Usual Suspect" wrote in message
obal.net...
cr500r sez:


http://www.wikihow.com/Convert-a-Com...o-a-Lab-Power-
Supp
ly

Aw, but they're *switchers*. A last resort for a bench supply, imho.
--
Al, the usual

yep, older hp,harrison bricks!

an hp6200b has been my companion for YEARS!

analog meter, basic controls, two plug terminals front, all sorts of useless
terms on the rear too!

stay with a basic type, no frills that will distract u from the task at
hand.



"Usual Suspect" wrote in message
obal.net...
I want to build a bench power supply, and am looking 'round the net for a
good circuit.

Requirements: 2 outputs, adjustable v, adjustable i, v & i meters (or
digits). Prefer 30v max, or similar. Preset v selections (5, 12, 15, etc.)
would be nice.

Here's one I found, complete with the designer's smiling face on each
circuit
illustration:

http://members.shaw.ca/roma/supply-4.html

What's your favorite circuit? Features you like that I haven't mentioned?

Thanks,
--
Al, the usual