Diy Bench power supply
Ive always wanted a bench psu but a decent one seemed too expensive so like most hobbiest i been just using a old ATX pc power supply. These re-purposed ATX supplies do the job fine for fixed voltages such as 3.3v ,5v and 12v but i wanted a varible supply above 12v.
I found this variable voltage 0-35v / constant current 0-3A regulating panel mount display on eBay for £20 . Rather than building something from scratch i decided to give it a try . The unit has a small colour LCD display and has a rear fan that comes on above 2amp draw. The unit displays indicates the set and measured parameters and includes various modes options such as default voltage.
Caged 24v psu (ebay non branded)
I had a 24v psu 2.5amp lying around again from a old project so decided to use that . To be honest it isn’t the best quality and wasn’t expensive but was a good size to fit the case.
Case & Design
I also recycled an ABS project box from an old project that was never finish hence the random cut outs at the rear!. I tried improving it by gluing a plastic mesh behind the holes and now its added extra cooling as well making it safe from fingers !.
Everything seems to fit in snug but Will have run a few tests to ensure the cooling and space is adequate . Although being a tight fit the size makes its ideal for use in on my ever reducing hobby space… working its way outside to the garage by Christmas haha !
The wiring was so simple as the regulator had just input and output terminals . I also added a inline fuse (DC output from regulator) to protect the regulator unit. The AC mains enters the unit via a fused IEC (kettle lead socket) At present i haven’t put a mains switch on the unit as when i needed it i will control at the wall socket . Although the DC output can be switched on and off via a button on the regulator.
I’m very happy how the unit turned, its a great size and best of all it didn’t cost me a lot as well as re-using old parts. After hours of load testing the unit doesn’t seem to get hot therefore the space inside must be ok.
The regulator unit works really well only thing is the on screen font is small and not as clear stood far back but i may try and fit a panel meter or put one on my mk2 . The regulator unit also doesn’t seem to have a heatsink but a fan that operates above 2amp draw. Although the chips haven’t got very hot so the PCB Heat sinking and fan must be ok i guess.
Also I think the caged psu isn’t the best quality hence its emits a bit of audio noise and unloaded the voltage seems to drift. I was able to rectify this voltage drift simply putting a load resistor across the psu output terminals to put a very small load on it less than 100ma. Overall it seems to operate ok and the voltage and ac ripple are good enough , you get what you pay for i spose.
Would this replace my hacked ATX supply ?
Simple answer No , with only 2.5amps max (ok for most stuff i do) and only a single output i would use this in addition to my ATX supply.
PLEASE NOTE LIVE MAINS VOLTAGES ARE PRESENT ON PSU IF UNSURE ALWAYS SEEK PROFESSIONAL ADVICE WHEN CONNECTING UP !
Please only use this for reference with to the correct manuals and datasheets. I hold no responsibility to any damage to any equipment caused .