Uploaded November 2014 | Updated September 2026, 2 weeks ago
This video documents the modifications that I had to make to the (cheap Chinese imitation of the Japanese) REX C100 PID controller that I bought on eBay. The three modifications I make are: (1) Convert the otherwise-220VAC controller to run on 9VDC, since I don't have access to 220VAC (2) Remove the mechanical 3A relay that the controller uses to switch mains power to the output terminal, in preparation for using the output to trigger a solid-state relay instead (3) replace the 5V voltage regulator (7805) with one that is capable of supplying more current (ie: switching the 100ma TO-92 package out for the 1 Amp TO-220 package). Hopefully this info will help others who purchase these inexpensive PID controllers. Thanks to this video for info on the relay conversion: youtube.com/watch?v=2NpcMycHDvk&list=WL&index=55
UPDATE: A couple things that I didn't consider before making the video, but corrected afterwards: (1) I am using the cord that came with the oven for the 110VAC. It has a polarized plug and I didn't pay attention to how I was using it. I have since fixed it so that the HOT wire goes to the SSR's control voltage connector and the NEUTRAL wire is the one that goes to the elements. If you look at my diagram in the video, what I just said will make more sense. (2) In my diagram, I drew the fuse in the wrong place. I've since located it on that HOT wire that I just mentioned. So it goes: HOT wire to 12A Fuse to SSR. Basically, I know enough to be dangerous sometimes and didn't consider those two safety issues until recently.
ANOTHER UPDATE: I just turned everything on, chose Autotune and the controller seems to have come up with PID values that work for this oven. It was all over the place before that (getting hot way beyond the set value). It seems like it's going to do exactly what I need.
This video documents the modifications that I had to make to the (cheap Chinese imitation of the Japanese) REX C100 PID controller that I bought on eBay. The three modifications I make are: (1) Convert the otherwise-220VAC controller to run on 9VDC, since I don't have access to 220VAC (2) Remove the mechanical 3A relay that the controller uses to switch mains power to the output terminal, in preparation for using the output to trigger a solid-state relay instead (3) replace the 5V voltage regulator (7805) with one that is capable of supplying more current (ie: switching the 100ma TO-92 package out for the 1 Amp TO-220 package). Hopefully this info will help others who purchase these inexpensive PID controllers. Thanks to this video for info on the relay conversion: youtube.com/watch?v=2NpcMycHDvk&list=WL&index=55
UPDATE: A couple things that I didn't consider before making the video, but corrected afterwards: (1) I am using the cord that came with the oven for the 110VAC. It has a polarized plug and I didn't pay attention to how I was using it. I have since fixed it so that the HOT wire goes to the SSR's control voltage connector and the NEUTRAL wire is the one that goes to the elements. If you look at my diagram in the video, what I just said will make more sense. (2) In my diagram, I drew the fuse in the wrong place. I've since located it on that HOT wire that I just mentioned. So it goes: HOT wire to 12A Fuse to SSR. Basically, I know enough to be dangerous sometimes and didn't consider those two safety issues until recently.
ANOTHER UPDATE: I just turned everything on, chose Autotune and the controller seems to have come up with PID values that work for this oven. It was all over the place before that (getting hot way beyond the set value). It seems like it's going to do exactly what I need.
