Hi Everyone,
Thought I would share a project I've been working on lately. I have been needed a load tester for some time, but I've been getting away with things like this
![Grin ;D](https://www.eevblog.com/forum/Smileys/default/grin.gif)
![](http://imageshack.us/a/img209/626/o7tp.jpg)
Yeah, that's just a lot of power resistors mounted on a fan
![Smiley :)](https://www.eevblog.com/forum/Smileys/default/smiley.gif)
Anyway, I want to build this new load based on what parts I already have, the goal is not a precision instrument. But something better and easier to use than a lot of power resistors.
Basic schematic, very simple:
![](http://imageshack.us/a/img838/3972/o06l.png)
The use of LM358 will probably not let me go all the way down to 0mA, but that is fine for my use. And the IRL2203 is because I had a few of them from another project, should work fine for this project.
I will use a 20x4 (HD44780 based) LCD display and a PIC24 micro, here a quick test setup for the control part:
![](http://imageshack.us/a/img542/1674/i2hx.jpg)
I'm aiming for 40-50W continuous and slightly higher short term. Low voltages only, maybe up to 20V, and features like constant current, constant resistance and constant power. I could do constant voltage as well, but I don't really like that feature. Also I'll try add some pseudo random noise feature.
I have decided on 1 encoder to set the modes and values, and 2 buttons, one for selection and one to start and stop the load. Plus a single LED to indicate if the load is on or not.
A low voltage cut out and a mAh counter would be handy for battery testing.