# Favorite bench supply circuit?

U

#### Usual Suspect

Jan 1, 1970
0
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,

D

#### D from BC

Jan 1, 1970
0
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,

Most often my prototypes include a power supply...
I seldom use my homebrew power supplies.
Also, when I do need a power supply it's usually some punk voltage
like 54V at 3amps.
Better to put time into unique projects and buy a power supply.
D from BC

M

#### [email protected]

Jan 1, 1970
0
Most often my prototypes include a power supply...
I seldom use my homebrew power supplies.
Also, when I do need a power supply it's usually some punk voltage
like 54V at 3amps.
Better to put time into unique projects and buy a power supply.
D from BC

I couldn't agree more. There are so many used supplies that it isn't
worth the effort to build a bench supply. Just the damn box and a heat
sink will be about $20, which is what I pay for bench supplies. D #### DaveM Jan 1, 1970 0 Usual Suspect said: 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, 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. M #### miken Jan 1, 1970 0 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, Saw in that web-site this statement ".....the notorious LM723 , a versatile but rather unfriendly IC...." Can someone please tell me about the unfriendly side of this IC. I just bought 50. Thanks de miken D #### Dave Plowman (News) Jan 1, 1970 0 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. S #### seanacais Jan 1, 1970 0 Here is a simple one for 0-30V @ 3A with current limiting http://www.electronics-lab.com/projects/power/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 R #### Rich Grise Jan 1, 1970 0 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 R #### Rich Grise Jan 1, 1970 0 Saw in that web-site this statement ".....the notorious LM723 , a versatile but rather unfriendly IC...." Can someone please tell me about the unfriendly side of this IC. I just bought 50. Too Many Leads. ;-) It also could be persnickety about input and output cap. values, but that's just a WAG. Cheers! Rich T #### TimPerry Jan 1, 1970 0 Usual said: 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. M #### [email protected] Jan 1, 1970 0 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-6200B-20-OR-40-VDC-BENCH-POWER- SUPPLY_W0QQitemZ330093581220QQihZ014QQcategoryZ58286QQrdZ1QQcmdZViewItem> 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&itemcount=8&refwidgetloc=active_view_item&usedrule1=UpSell_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. E #### Esther & Fester Bestertester Jan 1, 1970 0 THERES RAJ, BLR sez: 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

N

#### N Cook

Jan 1, 1970
0
Usual Suspect said:
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,

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

U

#### Usual Suspect

Jan 1, 1970
0
cr500r sez:

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

C

#### cr500r

Jan 1, 1970
0
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.

G

#### Guest

Jan 1, 1970
0
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.

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