3A Dummyload. 2014-12-23

I needed a dummyload for different testing in my lab so i started to google for a suiteable design to start from. I found the one from  EEVBLOG #102 to fit perfectly.

The power circuit is basically identical to the EEVBLOG's but i added aditional functions with the help of Pic 16F1847.

The dummyload can handle 3A/ 40V/ 50W. I have tested it with 40W continuous without any issues. Above 40W the heatsink and fan cannot cool the FET enough and it will be overheated after a while. With bigger fan and heatsink this can be avoided. The Pic measures the surface temperature on the FET. Above 45degC the fan will start, and above 85degC the DUT will be disabled to ensure that the dummyyload will not be overheated.

Also there is warning when over voltage/ current/ power occurs.

Not everyday i need to use almost all of my lab equipment. Even the homemade dummyload was used to simulate different load currents.

Control panel. 2014-07-01

I needed a control panel for my heater system in my house. The main feature was to be able to set  the temperauter from the panel instead of going down to the basement to set it. Also i wanted to be able to see the ambient room temp. I also added battery backup solution for the room panel.

The Danfoss regulator in the heater has a communiaction bus similar to RS485 but Danfoss has altered to fit their application. My first idea was to hack into this bus but i soon realized that it would be to much work since they used a non standard protocoll.

I therefore decided to  use a model airplane servo to mechanically push the buttons on the Danfoss regulator.

Below  is the  panel mounted in the hallway fully operational.

The chosen  PIC for this project was 16F1973.  There is a overcurrent protection circuit  to the servo. If the servo consumes to high current the panel goes into protection mode and the  shuts everything of. Then a master reset is needed.

Mechanical solution of the button pusher