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Archive for the ‘dummy load’ Category

As seen here, Juan had some problems with his power supply, and while he wanted to “simply” build another one, he didn’t let the power supply go to waste. Instead he converted it into an adjustable dummy load based on the design by Dave Jones’ shown below.

This device, however, is no mere duplication of Jones’ and adds an Arduino for control, allowing for voltage, current, power, and temperature monitoring. The enclosure was designed in Fusion 360 and 3D-printed, and the front panel overlay in Inkscape. 

Other interesting tricks include using a readily available DC motor for input instead of an encoder, along with an array of 7-segment displays that don’t quite all match, but act as functional outputs nonetheless. 

Code for the project is up on GitHub.

Sometimes it’s necessary to make do with whatever parts one has on hand, but the results of squashing a square peg into a round hole are not always as elegant as [Juan Gg]’s programmable DC load with rotary encoder. [Juan] took a design for a programmable DC load and made it his own in quite a few different ways, including a slick 3D-printed enclosure and color faceplate.

The first thing to catch one’s eye might be that leftmost seven-segment digit. There is a simple reason it doesn’t match its neighbors: [Juan] had to use what he had available, and that meant a mismatched digit. Fortunately, 3D printing one’s own enclosure meant it could be gracefully worked into the design, instead of getting a Dremel or utility knife involved. The next is a bit less obvious: the display lacked a decimal point in the second digit position, so an LED tucked in underneath does the job. Finally, the knob on the right could reasonably be thought to be a rotary encoder, but it’s actually connected to a small DC motor. By biasing the motor with a small DC voltage applied to one lead and reading the resulting voltage from the other, the knob’s speed and direction can be detected, doing a serviceable job as rotary encoder substitute.

The project’s GitHub repository contains the Arduino code for [Juan]’s project, which has its roots in a design EEVblog detailed for an electronic load. For those of you who prefer your DIY rotary encoders to send discrete clicks and pulses instead of an analog voltage, a 3D printed wheel and two microswitches will do the job.

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