Buck converter power supply

@tinkerman

Looks good and quite handy. Do you find that it gets hot after prolonged use ?

@will

Honestly I've only used it while testing components, nothing more than 10 to 15 minutes with no heat.

But that is something I did not think of in the original design.  I think I'll add some vents to the case and keep a little 5V fan handy.

@tinkerman 

Thanks for the info. I was thinking of making something similar with a 2.1mm x 5mm power jack on the back and 5V, 6V, 9V and 12V outlets on the front (sort of a universal supply) but I was afraid that it would melt or damage the PLA case.

I have some 5V 25mm fans, I think I'll add some side vents and a fan on the top to push the hot air out. Sounds like I can add a switch to it because I won't need the fan for short use periods.

Hi @tinkerman  & @will,

  Neat unit .. well done.

 You rightly discuss the question of heat from the regulator modules .. but if you use connectors, particularly ones with small contact areas like the 2.1mm x 5mm types, beware of the possible heating problems.

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 A couple of thoughts if you decide to develop any new units:-

Beware of expecting 2.1mm x 5mm plug/sockets (and similar small sizes) to pass too much (continuous) current. They can get hot enough to melt the plastic of both the plug and socket, which is pain to fix. The problem being the centre pin has only a tiny contact area.

Exact acceptable currents probably depend on quality of plug and socket, which are probably down to luck. I have only limited amount of (painful) experience, e.g. from a laptop designed by a well-known company that should have known better, so I can only make rough guesses. I doubt if up to 1A will cause any issues, and up to 2A will probably be OK, but above that I would advise finding a better connector.

To avoid you spoiling a new plastic moulding, I suggest you test any plug/socket combination at the current levels you expect it to cope with. Wrap some thermal insulation to mimic the effect of your box, and leave it passing current for an hour or so, checking to see if gets hot, every few minutes. If you feel it getting even a little warm, that is a warning sign and suggestion to widen your search for a new plug and socket. That 'little' warmth can increase to plastic melting temperatures with usage, possibly leading to a premature failure.

For modest increases, up to say 4-5A, the same shape plug/sockets, in a larger size, particularly the diameter of the centre pin, might be convenient without breaking the budget too much.

.......

Please note: Obviously these plugs are only suitable for low voltages of up to say 25V as the terminals are exposed. However, the amount of heating only depends on the current, not the voltage. However, heat generation is an indication of voltage drop.

Using connectors that get warm on the input to a voltage regulator, as in your present unit, the voltage drop may be compensated by the regulator with no adverse effects in most cases.

But, if connectors that get warm are used on the output, the voltage drop may be more significant, as it will reduce the voltage supplied to load, increasing the risk of problems like processor boards that 'crash'.

Of course the healthy sized output plugs on the illustrated unit should be fine for many applications!

'''''''''''

Sorry this is a bit long and 'geeky' but I hope it will save you from disappointment. Good luck!

@davee 

Thanks for the advice and especially for the explanation. You've pretty much talked me out of my original design, sounds like I'd be a whole lot safer to spend the $$ and buy a proper bench power supply.

I think I'd still like to make a 5V version, just to get rid of all these power banks that always seem to be drained when you really need them 🙂

Hi @will,

   Thanks for your kind reply.

   I certainly didn't want to put anyone off designing and building something ... just to point out that the 'little things' like connectors sometimes need as much care as the high profile stuff, if you want a reliable result. An infuriating trick of connectors is to work when you first put something together, but then progressively fail over a period of time. Hence, if you are making something to use for a while, it is worthwhile being a little 'generous' on your choice.

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I guess it depends what you are trying to do and what is important to you.

If you want to build a handy power source or two ... go for it! I was hoping to reduce the chance of you suffering an unexpected problem and avoidable disappointment if it didn't work as well as you expected.

If you want to build something else, that needs a power supply, and you can afford a commercial one, then maybe buying a ready made one, will allow more time to concentrate on your main project.

Stay safe and have fun, whatever you choose!

@davee 

You didn't "put me off" it, a bench power supply has a lot of benefits such as much higher currents and voltages, ability for constant voltage and constant current, built in gauges to get volt/amp and power use.

Besides, I'm getting slower and starting a flash fire from a duff design would be both embarrassing and disconcerting 🙂

Just and FYI, this power supply is not meant to be used long term.  I wanted something I could easily build and use for "benching" ideas.  I would not want to use it over long periods of time as I too would be concerned about overheating or other issues.

As my shop grows there will be a dedicated power supply.  For now the power supply works great but I do appreciate the feedback...more knowledge is always welcome.

Hi @tinkerman,

  Thanks for your reply. As I said, I think you have done a great job, and obviously you haven't used any small pin connectors with your 1st project, so it was only applicable for any follow ups you or anyone else might consider.

I was only 'inspired' to write after seeing @will 's comment and thought maybe someone would think it was a good idea, not realising that it might not work as well as they expected, and lead to disappointment.

As I mentioned, my own experience of those particular connectors arises from one of my (now) older laptops made by a well-known global company, whose design resources would have been practically infinite compared to most of us. I am still using it in a limited way, but it is on its 3rd socket, countless plugs, and the case is locally melted and broken in the vicinity of the socket  - not a pretty sight!

Best wishes and good luck wth your projects.