Introduction: Simple Bench Power Supply Using an Old Laptop Charger
So this is my bench power supply, it's a very simple build with only 4 wires to add / connect. The main power comes from an old laptop charger which can deliver 19v and 3.4A max. It's worth mentioning that the laptop charger is a 2 wire version from an Acer laptop. A lot of laptops these days use a 3 wire system which wouldn't work in this instructable without further electronics changes (maybe someone out there could show us how to make the 3 wire chargers also work?). It also worth mentioning that if you didn't have an old laptop charger then a DC power supply like this one could be used instead but you'd need a matching panel mount socket as well.
The voltage and current regulation are done by a RIDEN® DPS5005 50V 5A Buck Adjustable DC Constant Voltage Power Supply Module available online. There are different versions of these which can handle more or less voltage / current etc but I went for the 50v 5A max variant as it was more than the laptop charger could provide. Bigger versions have a separate PCB and in some cases a cooling fan so they wouldn't fit inside the 3D printed housing I've included here.
The housing was 3D printed as I have access to one and I've included the .stl files in the instructable. If you don't have access to a 3D printer then a suitable plastic enclosure could also be used instead. The total cost of this was under £30 including the 3D printer filament. I've attached all of the .stl files for the enclosure with 2 different boxes, one for the socket i'm using and one for a panel mounted socket.
Ok so you can buy a complete bench power supply for around £50 these days. However, from experience they generally only allow current control in 0.1A steps and in some cases 0.2A or 0.3A is the lowest they will go. With the DPS5005 you can control from 1mA in 1mA steps if you need to. This level of control puts this unit inline with much more expensive bench power supplies.
1) 3D Printed Enclosure (could use a bought enclosure instead) - £2 (Filament only)
2) RIDEN® DPS5005 50V 5A Adjustable Voltage Power Supply - £23 - Banggood
3) 2 x Banana clips - £1.15 -banggood
4) Some wire - Already had some lying around
5) Socket to plug charger in - I reused the one from the laptop as the laptop was no longer working (A chassis mount socket could be bought to suit the charger plug).
6) Some small screws - again these were already lying around at home
Step 1: Fit the Banana Plugs to the Housing
Split the banana plugs open and pass them through the housing, Simply tighten them back up an ensure the eyelets (now shown with the wires soldered on) are also fitted behind the nuts. A trick here is to open the front part of the banana clip and there is a small hole (which can used for connecting wires in used). Insert a small screw driver through the hole and this will stop the banana plug spinning when being tightened.
Step 2: Add the Charger Socket
Fit the charger socket to the back of the housing. fit the small strap over the top and screw into position. If your using a chassis mounted socket then fit the socket through the housing and tighten the screws. The charger socket rescued from the laptop had damaged wires so I swapped them prior to fitting the socket. Make sure you use wire that is rated above the Ampage of your charger.
Step 3: Fit the DPS5005 Into the Enclosure Lid
Simply push the DPS5005 in through the lid and click into position. If your using a stock enclosure then you'll need to cut out the lid ready to accommodate the DPS5005 first.
Step 4: Connect the Wires
Connect the 4 wires to the DPS5005 ensuring to get the right wires in the right place and the polarity is right.
Step 5: Fit Lid and Test
Finally screw the lid into position being careful to no trap any wires. Plug in the laptop charger and power on. I then set the voltage and current for an LED and connected it to make sure everything was working.