First PSU

[jesse86]

Hi all!

I'm looking to build (or buy) my first PSU. I've been watching Dave's videos (his usupply series and other PSU teardowns) and searching around the forums and YouTube trying to decide on what PSU I should build, and I'm sort of stuck in decision paralysis at the moment. From other posts surrounding this topic I know that people will want to know what I'm looking to do which makes sense and I'll list out some stuff below to help guide this. But ultimately what I hope is that some more experienced folks will chime in with some of their thoughts having looked back at their own journeys, with input on what they wish they would have started with.

I think my constraints are:
- I don't know how far down the rabbit hole I tend to go with this, so a low budget to start, ideally under $100 if possible
- multiple outputs or ability to make a few on the cheap
- enough to power arduino / pi and some smaller components / servos
- for someone inexperienced that doesn't want to blow up too much stuff, maybe some safety features perhaps?
- something I won't immediately regret and will last me a while
- If possible, something that could evolve over time / that I could improve as I learn more

Projects I'd like to tackle, starting with some more near term ideas and then down the line:
- use it to get hands on experience and learning, as I've spent long enough watching YouTube videos and not jumping in myself
- design or make other useful projects that are useful with electronics work (decade resistor?)
- powering temperature sensors and using them to do pid control, load cells, building other shop tools and instrumentation
- building small hydraulic pumps controls, small servo projects
- working with different sorts of rotary and linear encoders
- small custom CNC builds (probably using arduino and custom logic to start, maybe using legit GCode with linuxcnc down the line)
- larger motor control for more powerful CNC applications

Cheers!

[admiralk]

The simple answer is to get one of these

But not necessarily that model. You can power it with a wall-wart and as long as the wall-wart can supply more than you need, you are good to go. You can always upgrade to a proper PSU later, when you need to. I forget the conversion off hand. but an old laptop power supply should give you better than 12V output.

[gbaddeley]

Do you want to learn about power supplies, or just get something off the shelf? Linear or switching? Need metering?

[jesse86]

Learning more about power supplies would be awesome! As for linear vs switching, it's my understanding that linear are less efficient but more accurate, and the increased weight is a non issue for my use case. Also metering would be nice to have, but is not a requirement.

Also, thank you both for the quick replies!

[jpb]

admiralk' suggestion is a good one given your budget of $100.

You have the advantage of being in the US where things are cheaper, but you probably should look to getting a good quality linear supply off ebay or perhaps build your own.

To give an idea of what it is possible, I just bought one of these:
https://www.conrad.com/p/ea-elektro-automatik-ea-ps-3032-05b-bench-psu-adjustable-voltage-0-32-v-dc-0-5-a-160-w-no-of-outputs-1-x-510716
off ebay for £80 which is less than $100. It is not a top flight power supply like an keysight or keithley one and it is probably quite old but it is in very good condition - looks barely used.
It only has one output though.

I would avoid cheap new supplies as they are probably noisy (switching ones) and possibly dangerous.

The problem with $100 as a budget is that it is hard to get a good quality newish supply with more than one output for that sort of budget.
I had a brief look at ebay and the best I could see was this one:
https://www.ebay.com/itm/HP-6236B-Triple-Output-Power-Supply/313011889896
But it doesn't look in wonderful condition. One option would be to get it for $61, check it produces output (it is described as used so should work) and then clean it up and possibly replace the Electrolytic capacitors in it. If you have to repair the thing or restore it you will learn about power supplies and might end up with something good quality - but do some research first.
If you get something that old, it is a good idea to open it up and check it out before using it. But as you're a beginner I don't want to advise you to mess around with power supplies unless you know what you're doing - anything with mains voltage can be dangerous and that includes a charged reservoir capacitor even if the thing is not plugged in.

Here is a thread on it:
https://www.eevblog.com/forum/testgear/hp-6236b-triple-output-power-supply/

This one looks better, though pricier:
https://www.ebay.com/itm/HP-Hewlett-Packard-Agilent-6236A-Triple-Output-Power-Supply/114185828884

[MarkF]

I really like these little HP Power Supplies for small projects.
I have four of them.
No fan.  So quiet.
The only drawback is the low power output.  If you can live with 400mA, they are great.
Look for the ones with two concentric adjustments for voltage and current (i.e. coarse and fine).
Some only have a single pot for each.



They can be had for $50 to $60 (shipping included) if you search eBay.
Hewlett Packard HP 6216A 0-25V/0-0.4A