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October 25, 2011 AT 7:10 am

HOW-TO: Make a variable DC power supply

Makepowersupply-Copy

How-To: Variable DC Power Supply @ MAKE.

Hobbyist electronics projects need robust, reliable power supplies for prototyping and testing. I learned how to build this circuit from the Basic Analog Circuits class at ITP taught by Eric Rosenthal, but took it several steps further in building a solid enclosure and integrating a voltage meter. Now it lives on my desk, ready to power most small projects I’m working on, ranging from 0 – 24 volts and up to two amps. You can learn all about how to make one yourself using this Make: Projects tutorial.

The mini volt meter from Adafruit is what brought this project to the next level. All of the components on this three-digit, seven-segment display are packaged into a small size. All you need to do to integrate it into any project is attach a positive and negative lead to whatever you wish to measure.


Minivotmeter Lrg

Mini Volt Meter. Put a voltage meter anywhere with this very handy display. These are often used by RC hobbyists for keeping track of batteries but we thought it would be great on a breadboard or enclosure.

Minivotmeterback Lrg

Simply connect the red wire to the positive supply, and black to negative ground. The display has a microcontroller that will read the voltage, compare it to a stable reference and display the voltage with 0.1V precision on a 3-digit 7-segment display. It works from 3.2V up to 30V so it will be good for nearly any electronic project! The meter draws 3-4mA to power the microcontroller and display. This particular LED display is a nice vivid green, which we found very readable. Mounting tabs make this module easy to attach to any box or plate.

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