60W Electronic Dummy Load Mod 20mA to 999mA

[voltlog]

A viewer asked on youtube if this electronic dummy load could be hacked to work lower than 0.2A. In a previous video I explained the limitation is probably given by the low value 10mohm shunt resistor. The dummy load is rated up to 10A so it has to use a small value shunt but that 10 mohm resistor cannot generate a high enough voltage drop for currents less than 0.2A so that is probably why the load is software limited to 0.2A minimum. After reading the comment on youtube I immediately thought about experimented with a 0.1 ohm resistor and it works perfectly, the whole range is shifted by an order of magnitude and I can now adjust between 20mA and 999mA instead of the original 0.2A to 9.99A. Now I can test even low current power supplies or batteries. Enjoy the video and let me know what you think.

[mij59]

Put the shunt resistor on the other side of the board, where the high current traces are.
The traces on the component side are only used for voltage sensing.

[voltlog]

That is indeed a good point, the shunt resistor would be better mounter on the other side touching directly the high current path. In my case I am relying on the big plate through holes, filled with solder for the high current path which in this case is 1A maximum and will work just fine but if a higher current was used I would have to solder it on the back side as suggested.

Thank you.