Workshop Psu recommendations?

The market is awash with them, second-hand on eBay and new from various sources including Amazon. Depends on what you want and how much you wish to spend. As for safety, that depends on what and where you buy from, especially second-hand.

For example, I bought two from Amazon.

First; I bought this four years ago for £52, a Long WEI PS-305DM 0-30V 5A. The features it had that appealed, were constant current, constant voltage, two meters and a switchable for amp/milliamps. It's not missed a beat and has been really useful on numerous occasions.

Second; I bought two weeks ago, an OWON SPW3051, 0-30V 5A CC, CV, a 3" LCD display and lots of features, all for £80.99. The reason I bought this was I needed to provide a TV circuit with two independent voltages, a 24V supply and a 10.2V supply.

You may wish to consider this, as you can purchase PSUs that will provide two controllable outputs. A little more expensive, but so is buying two power supplies. I'd certainly recommend you buy one with at least over current protection.

Prior to this, I had a 1980s Altai, it was switchable from 0-12/24-24V at 3A. It also had a switchable single meter for Volts/Amps. Although the switchable power and meter were not a great problem, I did find it a pain. The Altai now resides on my store room bench, and it's developed a fault in that it only works on the 12V-24V range. As it does not have OVP or OCP, combined with the other limitations, I can't be bothered to fix it, so it will be replaced soon. I also had an old Philips, this did have current protection and two meters. When I bought my first new bench PSU, I passed this on to John, who was just setting up a workshop and did not have a PSU.

Hope that helps in some way. 👍 

I have 3 bench PSU’s here, one is a GW Instek, dual 18V @ 5A, I got it for nowt 12 years ago when the company I was working for shut down, it was still in its box with all its leads! Damn good power supply, has only gone wrong once, when I accidentally shoved 10KV back up the input, it toasted one of the digital meter chips, but a replacement cured it.

I also have a Wier single power supply, 60V @ 1.5A, very useful, particularly with battery valve sets, not quite the 90V they require, but normally enough for testing, and I can also couple it with another to get the voltage up a bit! This one was given to me years ago along with a load of other stuff.

my most recent one is a Thandar TS3021S, single 30V 2A, an eBay purchase for not very much because the output switch was broken, a replacement switch and a quick tune up and it’s working perfectly! These little power supplies are very good workhorses, along with the PL320’s, which are a later version. They come up on eBay occasionally at sensible prices, but there are a lot of overpriced ones too, service manuals are available online for these too which is a bonus. We use a lot of Thurlby-Thandar’s at work, they just keep on going! Some must be over 30 years old by now.

 Regards 

Lloyd 

Old Irwins have always done me well. Mine came from my schools science lab... Readily found on fleabay. 

A Thurlby Thandar PL320 - they just go forever. I also have a few Farnell PSUs from the L30 family and for stuff that bites, a Farnell E350 (the 100mA version) and two HPs that go up to 320V.

Agree you can't go wrong with manufacturers such as Thandar, Farnell, Weir etc

It all depends on intended use as to which voltage or current ranges are required. A standard output rating of 0 to 30V 0 to 3A is usual. 

Avoid those really cheap power supplies from China!

A Skytronic 650.682 40V 10A PSU had been chucked out from the R&D lab after it developed a bizarre fault with a two level Schmitt action output <0.1v and 45V caused by control circuit oscillation. This caught the technician by surprise as the system he was testing suddenly had full power delivered to it !! Inside the PSU there were no local decoupling capacitors on any op amps, no capacitors across the rectifier diodes, no mains filter capacitor or anything to protect against a high back EMF voltage developing across the transformer primary when switched off. Just one 100uF cap on each fixed voltage regulator output and a cheapo 220uF capacitor across the output terminals which had gone open circuit.  🤮 

Rich

Posted by: @marconi_mpt4

 

Avoid those really cheap power supplies from China!

I'll second that. Utter crap and risky for the items you connect to them.

At work, they bought five such things and they all failed just after the warranty expired.

They now only obtain TTI power supplies and we never have any problems. Ok, more expensive, but you get what you pay for.

@will Oh well, I guess based on these comments below, you'd best ignore my two recommendations. Even though they have been well reviewed by many independent techs.

Posted by: @marconi_mpt4

Avoid those really cheap power supplies from China!

Posted by: @pye625

I'll second that. Utter crap and risky for the items you connect to them.

👍 thanks chaps, lots to mull over there , farnells have some fairly cheap units in their stock , should I just buy a basic unit for now as I'm fairly green...

The psu's that are low-cost may well be great and perform well to begin with.

But they are not built to last. In my case, they have proven unreliable in the work place compared with more costly types.

However, in my workplace they are used on a daily basis. A low-cost device bought for occasional hobby use may well prove more reliable if not used all day and every day.

I would certainly not ignore crustytv's advice above, but you need to weigh up all the opinions and then decide.

I would say the Long WEI PS-305DM that Chris has should be a good unit, it looks similar to the GW Instek that I have, they have a proper transformer and well made PCB’s, and I’m sure I have seen the same case style hanging around for the last 20 years, even in my first workplace I remember seeing them! The one I have has certainly been hammered, I don’t think there is a day I don’t fire it up for something in the workshop, and I did almost fry it with 10KV, the only part affected was the digital meter, the actual output was still working fine.

Thats not to say there aren’t some absolute crap ones out there, there have been reviews of some of the cheapo switch mode types that showed them to be noisy on the output, or just damn right dangerous, you have to pick carefully. Size and weight will show up if it’s a proper transformer type or SMPS, and it’s worth looking up any model you are interested in for any YouTube teardowns, and reviews.

 Regards 

Lloyd 

@will TTI, Thandar, expensive to buy but properly designed and built to last forever. 

Got a link?

I've just been looking on eBay at prices of the Farnell L30 family: as the name implies, they are 0 - 30V at various currents. For fixing your typical transistor radio, a 1A supply would suffice and typically these start at about £49.

No links, obviously - that's policy here.

The Longwei power supplies have found favour in an unconnected area - providing power for old Hornby 'O' gauge trains, many of which ran from 20V DC.

@will Mike @cathovisor is correct eBay links, although not allowed publicly, can be exchanged privately via our internal messaging system. Just send Mike a PM and I'm sure he'll send it to you 👍 

I've been looking at those, I think one of those will suffice. 👍