Difficulty: 
(4/5)
My latest model is a Constant Current Power Supply that can handle 50 volts at 5 amps. The model in the picture was rendered in Autodesk Fusion 360 and can be easily printed on almost any 3D printer, I used a PrintrBot Simple 100mm x 100mm. This model has enough space to fit a DC-DC Boost Converter that takes a 12 volt input and boosts it to 35 volts. The 35V signal is then fed into the DPS5005 Constant Current Power Supply (PSU.) The manufacturer offers this unit in a range of different voltages and amp ratings and this model fits almost all of them. Mine can handle up to 50V at 5A allowing me to upgrade the 35V Boost Converter in the future.
In this picture you will see my working unit that utilizes an Arduino Pro Mini Micro Controller (MCU) with two thermistors to monitor temperature and controls a small 40mm X 40mm x 10mm 12V Computer Fan with one of its Pulse Width Modulation (PWM) pins. I have also allowed for enough room in the case for the Power Supply Unit (PSU) that comes with a Bluetooth Module used for serial communications. The add-on allows you to control it by turning it off, on, and change various settings wirelessly as well as a program for your PC. I haven’t used this feature yet but imagine it could come in quite handy.
I added a pair of the WS8212B RGB LED‘s which shine white when the temp is below 30ºC on either of the two heat sinks. Two 10K thermistors are used to sense if the temperature hits 31ºC. When it does the light changes blue and gradually to red as it reaches the max of 70ºC. The fan also speeds up using the same scale. I took the above photos while testing my unit with a car headlight as the dummy load.
I designed a Printed Circuit Board (PCB) in Autodesk Eagle that lines up perfectly on top of the Arduino Pro Mini. Keep in mind this part is completely optional, and might be for the slightly more advance maker. I combined all of the components required to connect the two temperature sensors, all the LED’s, and control the 12V cooling fan. You print the layout on a laser printer or any professional photo copier that uses toner and transfer it to a copper clad board using the Iron. I may create a separate post for the Ferric Chloride etching process that I use if there is any demand.
Parts List
- 3D Printed Case from Thingiverse
- DPS5005 Digital Constant Current PSU
- Arduino Pro Mini
- Custom Etched PCB (optional)10K Resistors
- 35 Volt 5 Amp DC-DC Boost Converter
- 12V Fan 40mm x 40mm
- WS2812B RGB LED
- 1K Resistors
- LM7805 Linear Voltage Regulator
- (2) 10K Thermistors
- TIP120 Transistor
- 12V Power Supply (amp rating depend on use)
- Female Banana Plug Sockets
- Male Banana Plug Sockets
- Male and Female Header Pins
- Female DC Panel Mount Connector
- Download the Sketch
If you’d like to see more please drop a comment below, email me directly using admin@triplemike.com or hit me up at any of my social links with your comments and suggestions.