DIY lab power supply
I was getting a bit frustrated with my old lab power supply, a Manson EP925. I bought it second hand many years ago during my student years. The problem with it is that it has only one output. For many electronics projects I need several voltages, like 3V3 and 5V.
Dangerous prototypes sells a PCB that lets you recycle an ATX power supply into a bench power supply. Unfortunately I didn’t have an ATX power supply laying around, but I did have a couple of old laptop power supplies. In combination with some cheap Chinese break out regulator boards from Ebay I made a lab power supply. The laptop charger I’m using outputs a stable 12V and can supply 5A. That’s more then enough for most electronics projects.
Here is the block diagram of my lab power supply:
Lab power supply
My DIY lab PSU has 10 binding posts in total. The ones on the left provide 12V, 5V and 3V3. The 12V output comes straight from the laptop power supply. The 5V and 3V3 are provided by a KIM055L and a KIM035L module. These can output 5A of current. The other 4 are the outputs of a LM2596-adjustable and a XL4015 regulator. The LM2596 is a simple adjustable voltage regulator board. I desoldered the trimpot and soldered a regular potentiometer to it.
The XL4015 breakout board is setup as a constant current regulator. It has 2 trimpots to set voltage and current. I again desoldered the little trimpots from the board and soldered 2 potentiometers to it. I fitted the 3 potentiometers to the front plate and added 3 nice buttons so I can easily adjust them.
The left panel meter shows the output voltage of the LM2596, the right panel meter displays the voltage and current of the XL4015 output.
I designed a box in Draftsight and had it laser cut in acrylic sheet by a local company. You can download the dwg file here. The design is for 4mm acrylic sheet, as that is what my local laser cutting company stocks. BTW Draftsight is a CAD program that is free to use, and it even runs on GNU/Linux.
I bought the regulators and panel meters on Ebay. The binding posts, potentiometers, buttons, power switch, fuse and DC jack come from Tayda electronics. To distribute the 12V from the laptop PSU to the different modules I used an 8 position screw terminal strip.
Lab power supply
Lab power supply
Nice build! Did you test the output of this? You’re using switching power supplies, so there must be noise and ripple on the output, especially when under load.
Yes I have tested all the outputs with my Rigol DS1052E scope. The KIM modules give a very stable voltage. The old LM2596 regulator is the noisiest of the bunch. While it is a 3A regulator, the other components on the board are not adequate for a 3A load. You can read about my “switch mode regulator testing” in this post: http://www.bajdi.com/testing-switch-mode-voltage-regulators/
I’ll only use this PSU for small loads, I still have my Manson PSU that can pump out a stable voltage under a 20A load.
Great power supply, but why didn’t you used the XL4015 for both regulated outputs?
I just used the parts I had on hand, only had one XL4015.
Useful project.
Do you have the ebay link for the XL4015 board?
I tried to modify a LM2577S+LM2596S boost-buck CV/CC module,
but did not work with the remote pots.
It’s sold as a 5A lithium charger: http://www.benl.ebay.be/itm/1PCS-5A-Lithium-Charger-Step-down-5A-Power-Supply-Module-LED-Driver-M4-/301124034247