Introduction: MCM Variable Bench Power Supply
As you learn more about electronics you quickly realize how valuable a variable bench power supply is. For the uninitiated a bench power supply is essentially a box that sits on your bench and let you control the power you supply to your project. Some power supplys allow for very little control such as choosing between 3.3, 5 or 12 volts. Others are much more accurate and allow you to control amperage and a load of other things I am still learning about.
Most electronics enthusiasts / Makers / Hardware hackers build their own power supply at some point as a right of passage, so I figured I would have a go. I love the Mid-Century modern aesthetic, so I wanted to infuse that look into my power supply to make it a bit different than the norm.
I should also mention that I have built this power supply using commonly available modules to speed up my build. This means I purchased electronic components that where assembled by someone else and connected them together to fulfill my needs. This is a quick and dirty way to do things. Much more accomplished Makers out there actually build the modules themselves. Respect.
Step 1: Bill of Materials
Here is the list of parts I used for this project. If you are a budding Maker you probably have some of these lying around already. In case you don't I've included links where you can find them.
- IEC Male Panel Socket with fuse link
- Toggle Switch link
- Laptop Power Supply 16V@4.5A link
- LM2596 DC Step Down Power Supply link
- Voltage Ampere Monitor LED Panel link
- Brushless DC Fan link
- LTC3780 Regulating Power Supply link
- 2 x Female Banana Socket link
- 200K Potentiometer link
- 500K Potentiometer link
- 2 x Top Hat Potentiometer Knob link
Step 2: Case Cannibalization
Instead of hitting the wood shop to create a case, I found an old alarm clock that looked great but had a very annoying ringer. So annoying in fact that I stopped using it a week after buying it. I gutted it and was contemplating replacing the Plexiglas front panel with a different wood species, but my father brought up a better option. My father is a tailor, so he suggested using some type of textile over the Plexiglas. We thought this would work and be a lot easier than woodworking.
Before covering the Plexiglas I mapped out where I wanted to put all of the components and slowly drilled holes or Dremeled the panel where components needed to fit.
Then my father and I dug around and found a piece of Ultrasuede that had a really great texture. I lightly sanded the Plexiglas, sprayed some adhesive onto it and stretched the Ultrasuede over it and folded it over.
Step 3: Wiring It Up
I routed two holes in the back panel of the alarm clock and placed the IEC socket and fan. The IEC socket was interesting as it included a fuse mount. Safety first.
Next I broke open the laptop power supply and glued it to the case. Then I wired the AC input to the toggle switch, and then onto the laptop power supply.
The laptop power supply outputs 16v which I wired to both the LTC3780 and the LM2596. The LM2596 converts the 16v to 12v, which I wired to the fan and the Voltmeter/Ampmeter display.
Then the LTC3780 was wired to the Voltmeter/Ampmeter display and the banana sockets.
Next, I desoldered the small potentiometers that control the voltage and current on the LTC3780. I wired the new ones to the board and then exposed the pots through the front of the panel. I then attached some 70's era knobs to the pots.
Step 4: Finishing Touches
I think it came out rather well. My father's idea of working in a textile really adds something unique to the project. I think I'll collaborate with dad more often. The only problem is, now my other equipment is jealous.