Bench power supply

[Steve MillwardParticipant @stevemillward84705]

Hi I’m looking for a bench top power supply 0 to 30volts 10amp

anyone got one any recommendations & price please

cheers

Steve

[Steve MillwardParticipant @stevemillward84705]

[John HaineParticipant @johnhaine32865]

There's a wide selection of used units on eBay. The ones we used at work were often Farnell, not sure if they ever did one that could do 10A. Other names are Thurlby, Thandar. Most of the test equipment suppliers have a range, you can pay a lot of you want to!

I have a 20v 5A one that came from Maplin, which is switched mode. Depending on what you want do use it for it may be better to look at a linear supply – the SMPS one I have is not awfully keen on pulsed loads. A couple of features that are nice to have: multiple outputs, a good accurate current meter (the one in mine is a sick joke), and some preselectable o/p voltages, say 5 / 12 / 24v as well as variable.

[V8EngParticipant @v8eng]

These people (Reading area) keep a wide range of good brands electronic kit. 
Might be worth ringing with your requirements.

No personal connections to them etc!

Stewart

Edited By V8Eng on 23/01/2023 16:43:33

[Nigel Graham 2Participant @nigelgraham2]

Thankyou V8Eng for that link, now book-marked in my 'Engineering' folder.

Thank you too, Steve, for asking in the first place.

(I want a PSU for a 24V motor for a milling-machine drive.)

[Robert Atkinson 2Participant @robertatkinson2]

What is your intended application?

300W is quite a big bench power supply. Basically you have a choice of "old fashioned" analog or more modern switch-mode. Linear is bigger heaver and generates more heat.
If your are going to power reactive loads like motors even a lower quality linear is likely to be OK but a cheap switch-mode may struggle or even go up in smoke.
My personal preference is Farnell or Thurlby / Thandar (now TTi)
A Farnell B30/10 will meet your spec for a linear but it does not have variable current limiting.

Robert G8RPI.

Edited By Robert Atkinson 2 on 23/01/2023 19:05:50

[HollowpointParticipant @hollowpoint]

I bought a cheap "Hanmatek" branded one from Amazon. I didn't expect much but I've been very pleased with it. I use it a lot, no issues. 👍

[Graham StoppaniParticipant @grahamstoppani46499]

I recently upgraded from my 5 amp power supply to a 10 amp power supply. I use them for component testing and electroplating. I bought my new supply for £67 including shipping from Gateros who I buy my plating chemicals from. See link below:

**LINK**

It has worked fine for what I bought it for. Its worth noting that my 5amp supply had fine and coarse adjustment knobs for current and voltage which this unit doesn't.

Graham

[Robert Atkinson 2Participant @robertatkinson2]

This link to what appaers to be the same PSU as Gateros are selling:

Includes internal photos. The images do not instill confidence that the unit would meed UK safety specifications.
For example the single insulated lowvaoltage fan wire close to the un-insulated mains inlet socket terminals. This would fail a certification inspection.

The lack of a mains switch is also a concern.

Robert G8RPI

[Henry BrownParticipant @henrybrown95529]

As Hollowpoint, I bought a Hanmantek 0-24V, upto 10A. I searched ebay for "used", "nearest first" and found it about 10 miles away. The chap was happy to demonstrate it working when I collected it.

[HowiParticipant @howi]

All depends on what you intend doing with it.

There is a difference between a power supply and a 'bench' power supply.

the latter will give a voltage range,normally up to 30 v, some will go higher.

they will have current limiting capability (can save your projects from emmiting magic smoke).

they will have volt and amp meters so you can see what is happening.

A lot of modern bench/lab supplies are now switch mode, smaller,lighter, cheaper than linear power supplies but electrically a lot more noisier with respect to RF emmisisons.

My bench supply is 0 to 20v at 1 amp and was built 40 years ago, has been rehoused many times and is my go to for all my electronic testing, current limiting being the most used feature that can prevent magic smoke.

I have been tempted by the cheap Chinese offerings (they are good value) but find my old mate is enough to do what I want.

As I stated at the beginning, it is down to what you are going to use it for.

[SillyOldDufferModerator @sillyoldduffer]

I've not found a perfect power supply yet!

I prefer linear because I'm a radio ham and switched mode supplies are radio frequency noisy. Doesn't matter for most electronics work. Downside of linear is cost!

Switched mode supplies are cheaper and often offer more facilities.

Fixed voltage supplies are much less likely to accidentally damage electronics than variable supplies, because they stop the clown at the controls setting the voltage wrong. But a variable supply is more adaptable.

For less than £150 my ideal supply would deliver low noise DC:

0 to 350V at 250mA
0 to 60V variable at 10A. Volts and amps both controllably limited, short-circuit protected, and metered
12V fixed up to 10A (Lots of equipment is 'car battery' compatible
5V fixed up to 5A (Old skool logic)
3.3V fixed up to 3A (Modern logic)
-15 Gnd +15V split rail variable up to 3A (OpAmps)

Doesn't exist!

Dave

[john fletcher 1Participant @johnfletcher1]

Not difficult to make your own basic workshop power supply. Here is my experience, several years ago I was give a discarded wheel chair battery charger, and used the metal box again, to house the bits for my bench power supply. I measured the transformer output voltage, it was far to high for what I needed , a few turn were removed from the transformer secondary As the outer turns were now a bit loose I sealed them with Araldite. To the case I fitted an ammeter, analogue type, and one of those Digital amp/volts meters as well. A full wave rectifiers and two 5000 micro farad capacitors ( pre owned) to add a bit of smoothing, to the output. I fitted a 10 amp variable voltage regulator from PRC on heat sink, which I had to hand. There is a fuses on the output and power ON neon indicator. Cost almost zero and almost bomb proof. It has been quietly working for the past 20/30 years. I regularly use the PSU to power a 12 volt modified cordless drill now running on 18/24 volts in my workshop. A large pre digital battery charger transformer is ideal to get you started. John

[Milly SParticipant @millys]

Hi all thanks for all your replies I’ve now ordered a 30v 10amp

power supply basic but will do what I need £47:99

ill update when unpacked & tried

thanks again

steve

[john fletcher 1Participant @johnfletcher1]

For anyone else needing a power supply unit, look up RSGB web site and see if there is a local Amateur Radio club near bye or when there is an Amateur Radio Mobile Rally in your area. These Amateur Radio Mobile Rally are dotted around the country through out the summer. Some areas have an auction sale, some would call it a junk sale, where things frequently go for a song. John

[John HaineParticipant @johnhaine32865]

Posted by Steve Millward 1 on 26/01/2023 15:09:38:

Hi all thanks for all your replies I’ve now ordered a 30v 10amp

power supply basic but will do what I need £47:99

ill update when unpacked & tried

thanks again

steve

Steve, could you say where from please?

[John HaineParticipant @johnhaine32865]

Posted by Steve Millward 1 on 26/01/2023 15:09:38:

Hi all thanks for all your replies I’ve now ordered a 30v 10amp

power supply basic but will do what I need £47:99

ill update when unpacked & tried

thanks again

steve

Steve, could you say where from please?

[Milly SParticipant @millys]

Hi the company I bought my power supply from is called

static arc

Based in Birmingham

[V8EngParticipant @v8eng]

That looks a useful supplier.

Duly stored for future reference thank you.

[BazyleParticipant @bazyle]

At that rate a psu plus 24v wheelchair motor is a contender for a small lathe rather than a VFD etc.

[John HaineParticipant @johnhaine32865]

**LINK**

Thanks!

[SillyOldDufferModerator @sillyoldduffer]

This could be a naive question but I notice lots of switched mode power supplies come with three terminals:

Does anybody know what the Ground terminal is for? I can think of a few possibilities:

• Gnd connects to mains earth and is made available for safety or to ground static. OR
• Gnd connects to chassis, and either the Plus or Minus terminal can be connected to it. This would allow the PSU to be configured to power 3 different combinations: positive ground equipment, negative ground equipment, or floating ungrounded equipment. OR
• Gnd connects to chassis with positive and negative arranged equally around it. So if the PSU is set to 18V out, -9V would be available on the black terminal and +9V on the Red – both relative to Gnd, a split rail supply.

Dave

[John HaineParticipant @johnhaine32865]

On mine the +/- are floating unless one side grounded.  The same is true on most lab linear PSUs as well, desirable feature to avoid ground loops in certain situations.

Edited By John Haine on 27/01/2023 16:04:00

[Robert Atkinson 2Participant @robertatkinson2]

I can confirm what John said.
The "GND" terminal is connected to the chassis AND mains supply protective conductor "Earth". The low voltage DC output is isolated from GND/Earth. The user can connect one or other of the output terminas to GND if they wish. This can help with electrical noise and safety or for compatibility with connected circuits.
The powersupply specification should say how many volts the output can be "floated" above ground without causing damage. A lot of low cost power supplies don't say. The output of these should not be taken much more than the maxium outut voltage above ground.

Some dual supples will have a 0V, positive, negative and GND terminals. For these the output is always symmetrical about 0V and any output terminal can be connected to ground. If the output is set to 12V and negative connected to ground the 0V terminal will be at plus 12V measured to ground and positive will be at plus 24V measured to ground.

Robert G8RPI

[Author]

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