Power Supply Front End - Alt Lab Supply by MCmaks

Last crawled date: 3 years ago

An inexpensive alternative to a DC lab supply. Essentially a power supply front-end with voltage adjustment buttons, LCD for voltage and current readings, banana jacks / binding posts, DC jack, and power switch. Built around a DC-DC buck converter board; output 0-16.5VDC, 3A peak, 2A continuous. The total parts cost is about 5 USD. It needs a positive tip power supply under 23VDC not included in that total; laptop chargers are pretty much ideal (~20V, >3A).
Dual Output Version
Thanks for the CAD models:
Banana jacks by Jeroen LodderSwitch by EdgeDC jack by Muhamad Sidiq
BOM:
Find the tip size of your wall-wart/AC adapter before buying the DC jack. Links for 5.5mm x 2.1mm as well as 5.5mm x 2.5mm are included below. The list includes things I suspect most people already have like screws and an AC adapter. Assuming those are on-hand, I calculated 4.29 USD for parts actually used (items 1 - 4 below). I selected parts with free shipping when possible, but some parts have minimum order quantities above what's needed.
1) DC-DC converter board
2) Banana jacks
3) Switch
4) DC jack, select your tip size
5) DC DC board screws, M2.5 x 5
6) Bottom cover screws, M3 x 5
7) Optional, rubber feet
8) Wire
9) Power supply, 2.5mm positive tip and cable
Assembly Instructions:
1) Print the body, bottom cover, and two buttons. Make sure the print bed is smooth because the bottom layer becomes the top of the assembled unit. (The texture of tape or glue may be transferred.) Buttons are small and may need some filing/pruning.
2) Optional: Paint/color the recessed text and the buttons.
3) Install the buttons; drop in, check they move freely and drop all the way down.
4) De-solder/remove the large blue terminal blocks from the DC-DC converter board. Clean out (wick or sucker) the plated thru-holes. You can solder wires ~6cm long into Vin/GND and Vout/GND to make wiring easier later.
5) Install the DC-DC converter board using M2.5 X 5mm screws (2X). The screw bosses should be effectively self-tapping. Check that the buttons now "pop" when pressed and when released.
6) Install the DC power jack, switch, and banana jacks.
7) Wiring: Use a fairly high-powered iron (GND plane and beefy bananas can suck the heat away before the temp gets high enough to melt the solder).
Solder red wires: DC jack+ to switch_in, switch_out to DC-DC board's Vin, DC-DC board's Vout to red banana. Make sure the polarity to Vin is correct!
Solder black wires: DC jack GND to DC-DC board's GND [by Vin], DC-DC board's GND(by Vout) to black banana.
8) Install the bottom cover with M3x5 flathead screws (4X). They should self-tap into the body.
9) Optional: Apply small adhesive rubber feet (4X).
https://youtu.be/syRFwWdw3rwhttps://youtu.be/0Hl5d5YSglQ