PSU to Serve (Laboratory Power Supply)

thingiverse

That is the so-called "Laboratory" Power Supply Unit. Needed to power and measure all that devices to be used in DIY projects. For a long time I did use the laptop power supply with a voltage switch (after equiped it with one of that $1 3-dgit voltmeters) + StepDown. Very nice and unexpensive setup, should I say. But not so nice when you own the 3D Printer. Finally I was ready to spend another 2 days on new project and now happy to present results to you. The PSU features regulated output voltage 0...23.5V, current limit setup upto 3A, small form-factor... Ok, you need the following to make one yourself (most of the parts should be modified that or another way but nothing too hard): 1) 24V 6A PSU available from a lot of sources. Found the cheap PSUs source here: EDT-100W AC-DC Converter 110V 220V to 24V DC 6A Power Supply Switching Transformer - we are going to load no more than 24Vx3A(/eff,~90%) - no more than 75W in well-ventilated device, hope that is OK. The price is less than $5! And I did not find any problems with components that PSU is made of. 2) StepDown module with all that settings and limits, B3603. Mine was bought years ago from Banggood for the same $12.10 as the sell now (bought 3 pcs). Sure you can find it cheaper. It is based on LM2596 so 3A current is the limit (well-ventilated, again). 3) mini360 step-down like that one from Banggood (to be honest, that are 5, not one, but at $0.70 each) - used it to power the 12V air fan (not going to drop the 24V to 12V using resistor, too much heat and no speed regulation). 4) C7 Power Socket 5) 13x8mm Rocker Power Switch (Mine Aliexpress switches source is not available now but hope you can find them). 6) 12V 40x40x20mm Fan - used Sanyo Denki KDE1204PKV1 Maglev fan just because have them :) Use any you have. With fan grill. 7) Deans T-Plug Male Connector ("Dean") (obviously you need the female connector part too). 8) M2-M3 Screws, wirezzz... Alligator clips! What should be done before assembly (you can get all info from uploaded photos): 1) 24V 6A PSU - desolder 24V 2-pin connector + right (looking at output PSU side) capacitor, resolder capacitor to the ex-connector place (and the wires going to StepDown to be soldered to the ex-capacitor place) 2) B3603 StepDown - desolder inter-board connectors, replace by wires (so that controller board, one with buttons, could be moved to the device front side apart of power board that will be located at the device's top). Desolder both power 2-pin connectors. 3) mini360 - fine as is but do not forget to tune it 12V-output. One more tip: mini360 is base on MP2307 chip that's high input voltage limit is 23V, not 24V so you should lower the voltage from 24A 6A PSU before - any diode or two will be OK. Or you can try setup with no diodes as the maximum limit is 26V or so. As for me, I decided not to risk (PSU to Serve, not to Fry). 4) As I forget to design M2 nut holders behind the C7 Socket so that you can screw when the case is closed, the C7 Socket needed to obtain melted-in nuts. Did it (check the photos). 5) Fine as is. 6) Cut wires, solder to the mini360 output, solder the mini360 input to 24V 6A output - that is. 7) How to fix firmly T-Plug Male inside the case? Easy! Make two half-holes on the both plug sides so that later you can fix it with 2 M3 screws. Check the photos. 8) Yes! Cut, flux, solder. Cut. Screw. Fun. Dimensions: 135x63x51mm, weight 300g. On 3D printed parts - you need to print Case Top+Bottom and the Buttons. Mine was printed using all PLA, black and yellow. Tried to design minimising supports but the air holes and some screw holes need support so printed using auto-support generation feature. Questions? Welcome!