Show your favorite and most used benchtop PSU

[JeanF]

Hi !

Maybe some of you remember my el-verycheapo PSU made from various bits and bobs glued to a piece of scrap plywood ? (see prev page) Well... now it's even more rocket science ! It's got a proper enclosure

check it out :




as you can see it even features a proper IEC C7 connector 

funny thing(s) : I didn't have enough banana sockets so I had to buy 2 more (the 5v and 12v GNDs) but they were slightly different and didn't fit as good as the others so I had to use a bit of hot glue afterwards. Aaaaaand also :  All I had in stock was yellow so I hand painted the 3v3, 12 and 15v GNDs in black 

 

[Bored@Work]

Hi !

Maybe some of you remember my el-verycheapo PSU made from various bits and bobs glued to a piece of scrap plywood ? (see prev page) Well... now it's even more rocket science ! It's got a proper enclosure

What a clever way to increase the initial fuel for a fire.

[JeanF]

Yeah, indeed cardboard and wood are good fuels 

You have a good point here. I am aware of intrinsic safety issues. As you may have noticed from my way of speaking*, this is more of a joke than a proper power supply. I'd never leave it powered without attendance and I built it only for fun in my spare time based on junk parts. I would be silly to use a metal case, proper insulated banana jacks, a fuse holder ect. with this kind of PSUs inside... The whole point was to save these parts from the trash bin 

* : at least that was my goal, but it's not as easy in English as in French for me

[robrenz]

I guess this will have to be my new favorite.  Only 500nV and 500fA setting resolution and 10nV and 10fA measuring resolution. It will just have to do for now

[con-f-use]

Maybe some of you remember my el-verycheapo PSU made from various bits and bobs glued to a piece of scrap plywood? [...]

=

[txescientist]

I agree, that is not the smartest thing to do, especially with available cheap plastic enclosures (I used mains wire distribution box :-)) but look at this thing>
http://tatstechtalk.wordpress.com/2010/10/02/i-already-dont-like-pcs-but-cardboard/
http://www.engadget.com/2010/10/01/recompute-cardboard-pc-in-the-flesh-its-real-it-boots-its-m/

[blackdog]

Hi nardev,

Thank for the compliment.
I build all kinds of instruments in these Cisco boxes 

Kind regarts,
Blackdog

[Chipset]

This is my lightly modified Danica TPS 20 linear supply. I rescued it from the basement of a high school with a severely neglected EE program along with the HP gear to the right of the pic (5316A, 2x 8111A, 2x 3478A (both under repair and not pictured), a tek TAS465, tek 308 and some other odds and ends.
I'm not one for analog dials so I got the digital displays you see here off of ebay. 5 digits might seem excessive for such a relatively low end supply but the price difference between 4 and 5 digit displays was entirely negligible. I wanted to make the mounting plate out of aluminium or steel but didn't have any at hand, so I painted a bit of mdf.
I also took the opportunity to replace the pots with 10-turn ones.

All in all it serves its purpose and does it well, it's no precision instrument but it works fine.
I get about 2 decimals of reliable accuracy and resolution, purists will shout at me for removing the analog dial and carving it up to fit the digital displays but it's far more useful now with dual readout than it ever was before.

[Kibi]

This one is my new favourite. I found it in a dustbin the other day, the meters a still spot on.




This one is my most used in the workshop.




This one is the most used in the house.
I also found this one in a dustbin a while back. It did not work, but when I opened it up it looked like it was someone's incomplete project that they got fed up with and consequently threw it away. I completed it and it works well. I don't know what make it is supposed to be (Velleman perhaps), but it's about 40W (20V 2A) with adjustable current limit, course and fine voltage adjustment. It's perfect little handy power supply to use when you are cosy in the house and just want to check something out without having to run out to the workshops in the freezing snow.

[Kjelt]

Up till last year I used my two Delta 30V 10Amp PSU the most. Last year a Delta 300V 5A PSU at the company blew and was cost effective beyond repair  .
I was lucky enough to be the one that was allowed to export it to my own shack and got it working again since this great company shares the datasheets 
(if you ask nice). So now this is my preferred PSU for most things.

[Electro Fan]

My most used is a Tektronix PS503A.


But my favorite is an HP 66000A mainframe.  Found it without the keyboard in the trash.  Took me 10 years before I got a keyboard for it - and come to find that the thing works perfectly.

That is all very cool!

[Mark Hennessy]

This one is the most used in the house.
I also found this one in a dustbin a while back. It did not work, but when I opened it up it looked like it was someone's incomplete project that they got fed up with and consequently threw it away. I completed it and it works well. I don't know what make it is supposed to be (Velleman perhaps), but it's about 40W (20V 2A) with adjustable current limit, course and fine voltage adjustment. It's perfect little handy power supply to use when you are cosy in the house and just want to check something out without having to run out to the workshops in the freezing snow.

I can tell you all about that one...

That was made at the BBC's engineering training site at Wood Norton, and it's my design (I work there). It's nothing clever; just an industry-standard floating regulator that everyone uses, but it's proved to be reliable and many have been made over the last few years. It was designed to be easy to build, which is why the PCB is TH and single-sided, and why connectors have been used where possible. The enclosure was chosen by someone else, and it did impose some mechanical and thermal constraints, but it's not bad overall.

It has adjustable current limiting (limit shown on meter when DC output is switched off, just like the TTi units) and an over-temperature cut-out. Regulation is done by a dual op-amp. The maximum voltage should be set (with PR1) to 18V with fine-volts at min, and about 0.4V higher with the fine-volts at max. Current should go to 1.2 or 1.3 amps, although I only used a 1N4148 as the reference for that, so it's not terribly stable with temperature (decided that didn't matter - you have to draw the line somewhere!). You should find that the voltage stability is pretty good for such a simple design.

No-one on the course has ever left with a partially-completed unit - we always make sure they are finished and tested - so I'm intrigued to know what you needed to do with it. I'm also curious about where you found it. I wonder who would want to throw away such a useful thing? Of course, not all broadcast engineers need to work with electronics these days...

I can send you comprehensive details if you like - drop me an email.

All the best,

Mark

[con-f-use]

I can tell you all about that one...

Even the schematics and partslist? It looks kinda cute... Where does one get the enclosure?

[Mark Hennessy]

I can tell you all about that one...

Even the schematics and partslist? It looks kinda cute... Where does one get the enclosure?

Yes, all of that and more.

However, let me speak to my boss first. Just to clear things from the BBC's point of view - because they employ me and it was developed on their time, it's technically their IP. I'm sure it'll be OK provided I put a suitable disclaimer on any documentation.

The case is a Lawtronics HSK220 - http://www.lawtronics.co.uk/heatsink.html

Mark

[txescientist]

Thanks 

[BravoV]

This one is my new favourite. I found it in a dustbin the other day, the meters a still spot on.

Don't know why, probably its just me, I really dislike those push buttons, especially that two at the top for current setting.

To me that both are so counter intuitive, it feels like when I was going to use it, had to pause for a while thinking and verifying the combination again in my brain to make sure I will be pushing the right combinations. 

Anyone have the same impression ?

[84GKSIG]

they do not come across as strait forwards as a rotary position switch would have, wonder how those beasts look inside 

[BravoV]

I guess probably with the consideration that it needs quite an expensive rotary switch to switch the high current connections, hence those cheap ugly push buttons.

[84GKSIG]

thats kinda what I was starting to think, how old are those?

[theonetruestickman]

Wow, so much awesome gear, though some of you appear to have a much different definition of "inexpensive" compared to me... 

The most used for my is probably the Heathkit ET3100 and one of the little switchable deals with interchangeable barrel plugs. Those are great for testing small consumer electronics for which the wall wart is MIA. The 12V lighter plug one is nice for testing stuff out in the car, too.

As far as *favorite*, I'll have to go dig out a couple of the telecom behemoths I've got stowed in the barn. Those are way cooler but far more power than I actually need to use for anything.

[VintageTekFan]

Wow, so much awesome gear, though some of you appear to have a much different definition of "inexpensive" compared to me... 

I've just been lucky that I live near a Polytechnic college with a large budget and poor security on their garbage bins.

[theonetruestickman]

Found it - favorite PSU I own, purely for the size of the transformer. 

[Clint]

I have a history or using Thurbry Thandor (TTi) PSU's and am now have 3 generations in dual PSU, the latest one is this one:

http://uk.farnell.com/aim-tti-instruments/cpx400d/power-supply-dual-60v-max-20a-max/dp/1853729

Its a beast and very stable, I have not done much with it and one thing I will do is spend some time to see how accurate it is over the voltage and current ranges.

There is not much in this price range that can do 20A at 20v and still do 7A at 60V ! so quite ideal for my amplifier work.

[Kibi]

I can tell you all about that one...

No-one on the course has ever left with a partially-completed unit - we always make sure they are finished and tested - so I'm intrigued to know what you needed to do with it. I'm also curious about where you found it. I wonder who would want to throw away such a useful thing? Of course, not all broadcast engineers need to work with electronics these days...

Hello Mark

Thank you very much for the information.
I rescued this Power Supply from a WEEE bin which was sitting just outside SCAR before decommissioning works commenced. Being from SCAR or somewhere thereabouts, my guess is that it belonged to one of the News engineers.
The next problem was that it could not be logged onto the system as a working bit of kit to be redistributed as a) it was found in a bin and it did not power up at all and b) it was neither asset marked, bore a serial number nor had any brand name on it (it is now clear why). Basically nobody was interested in keeping it for redistribution so I asked if I could keep it and repair it. Permission was granted.
Once I got down to repairing it, I found that the secondary of the transformer was disconnected and none of the power transistors were screwed to the side of the case. I remedied these faults and it did then power up but had an intermittent fault which I eventually traced down to one of the wires being disconnected from the current / voltage readout selection switch. It was difficult to detect this fault because the Hellermann sleeve was holding the wire in place.
I wonder if the original owner could be found and whether or not they would like their lovely little power supply returned to them in working order?

[Maximus]

Made this one myself!  I'm quite proud of it.  Although after a year of electrical engineering schooling I have come to realize just how basic it is.

the guts of my PSU

Its enough to do most basic work.