Main Site Documentation

Bench Power Supply - Dangerous Prototype's ATX Breakout Board, any experiences?


#1

I am using DP’s ATX Breakout Board for a cheap bench power supply. Figured it was safer than tearing apart an ATX ps myself, and cheaper than an actual bench supply. I haven’t had any problems with it, using it to supply 3V3 to my Cerb40s.

Anyone have any experience with this device beyond mine? I don’t own an o-scope, so I don’t know how smooth or clean the power is. Have I got myself a decent low-cost option, or am I running on borrowed time?


#2

you’re at the mercy of the 3v3 line from the ATX PSU. Most PSUs don’t do too bad a job at this, although it’s not intended for high current capability (therefore might not be a good alternative if you’re wanting to draw lots of current). You could always look at a simple LDO to take the 5v out and regulate it to 3v3 if you didn’t trust your ATX PSU - the LM1117 is a cheap part that could do the job (and GHI use their equivalent on all the USBizi family boards, the AMS1117, in both 3v3 and 5v0)

No, I don’t have the DP ATX BoB, but I have intended to add one to my next Seeed order, although I don’t have a decent ATX PSU that’s not in a failed state either :slight_smile:


#3

@ Gregg - I’ve built two different ATX-based bench power supplies, and while I haven’t done much testing to see that they’re outputting precisely the voltage they’re supposed to, they do a good enough job for my purposes, which was to provide sufficient current to drive full reels of RGB LED strips.

IMO, if you know a reasonable amount about working with electricity, it’s not difficult to build your own ATX-based power supply, and a bit cheaper than the DP board (though probably not if you count your time). Just have to keep in mind that there are some potentially very nasty capacitors inside, and keep clear of them.

But if you want plug and play, the DP board looks quite nice.


#4

I always find this sort of supply for bench use in prototyping dangerous. They can output very high currents in a short or fault condition.

They are also very poor at regulation unless you are pulling some load on the the outputs. They generally have a minimum load requirement so check on this. This has especial;ly been the case on the ±12V rails in the past.

Your initial cost for a dedicated bench supply may be higher but you have the comfort of current limit control which limits damage to your boards. You also get 0-30V output too which allows for testing of other voltage inputs and not just 3V3 and 5V. :slight_smile:

I am not sure where you live but the likes of the GW Instek bench supplies are not that expensive for a dual output type with display of voltage and current. I have a GW Instek scope that is now some 7 years old and it is still going strong.


#5

I just noticed that the BoB has a 9W 10R resistor which appears to be loading up the 5V supply so that the minimum load is created.

This is going to get hot :slight_smile:


#6

Man, I could really use something like that. Anybody know how long their DHL shipping to the US usually takes?

@ Dave: this has built in 1.25A breakers. Also the Seeed page says most supplies apparently don’t need the resistor. They include it, but you populate as needed.


#7

You may want to check out my build blog post.


#8

@ Brett - The linear regulator is a good suggestion, I’ll try to use that when possible.

@ devhammer - It’s the capacitors that convinced me to go with the board. Most recommendations involved waiting long periods of time for the caps to discharge, and shipping was faster :).

@ Dave - I’ve kept an eye (finger) on the resistor and it hasn’t gotten excessively warm. I’m not taxing the supply, either though. I just looked at the GW Instek supplies. Cheapest single out manual adjust was ~$200, a far cry from the $40 or so I spent on the board, case, and PS. (I didn’t buy the PS just for this, just happened to have an unused one previously purchased.) I would love a good bench supply, but my budget doesn’t allow for it, at least not until I sell a project successfully.

@ FireyFate - Sorry, I don’t remember how long shipping took. Less than the recommended time for letting the PS caps discharge…

@ ianleel74 - Best for last? That is SWEET! That’s some serious maker skills. Do you sell kits? My woodworking tools are a bit lacking…

@ EVERYONE - Thanks for all the input! It’s great to have such a wealth of knowledge and experience to tap into as I journey deeper and deeper into electronics.


#9

@ ianlee74.

Nice handywork and blog.

Not sure what your budget goes to but these guys might be handly for your new front panel.

http://www.frontpanelexpress.com/

I use the German office for my front panels, both commercial and hobby designs. You get some nice professional looking designs with logo’s, engraving etc. The software shows the price so you know the total costs.

Dave…


#10

Thanks, Gregg. No, I haven’t made any kits. Unfortunately, even to make kits would put the price higher than what you can buy a lab grade power supply for with lots of extra features. So, unless you have the time, tools, & scrap wood then it’s really not worthwhile. Unless you just have bags of money to blow…then, give me a call :wink:

Thanks, Dave. Thanks for the tip on Front Panel Express. I’m sure I’ll use them for something eventually.


#11

Mine showed up today… for the money it’s pretty nice and it’ll be way better than the pile of wall-warts I’ve been using!