Old 1000W oven to revise and add an arduino PID temperature control and an upload option to obtain special temperature curves.
This version is final for now.
x-arduino - 13.94 kB - 04/26/2017 at 16:31
a spreadsheet to get a view on the PID workings
spreadsheet - 47.83 kB - 03/31/2017 at 17:08
The different pin names between AVR and Arduino
spreadsheet - 45.17 kB - 03/31/2017 at 17:08
The case I used isn't very EMI resistant I've added earthing points to the metal parts. I regret not building the whole low voltage part in a metal box because tackling the intermittent LCD crashes now slows everything down.
Today's test went well except for a crashed LCD at least I think that was the case because the controller kept going, after a reset and position the TC cable well away from the power cables all was ok for the duration. I tried 800 and 650 °C for a few hours during which I tweaked the default parameters handsomely to reach the set value.
I have learned that the MAX board reading, under these conditions, is jittery at least, going to look into that (might be the oven's TC).
...And the program might benefit from using an average instead of a momentary reading for the PID calculation.
...And I have to play some more with the PID calc sheet to get a better feel for fine tuning and probably use that knowledge for adding auto-adjust in the future.
Since the program looks good I'll upload it in the file area.
except front plate, finished encasing
maybe today a real test ...
first, a thank you to all the people following this project. I switched off all the notifying emails ... so 12 followers to say thank you to.
the program was finished yesterday and ran for +24hrs without crashing.
In the unwanted signals department I had to place a metal screen between the power and logic.
The TC input on the MAX board has now two diodes in anti parallel and a X2 47nF and the 47nF supply cap is now 147nF.
The SSR switch now sports a snubber 100ohm-220nF X2.
Next, I will connect the oven and run a test with all the intended hardware.
I will post photo's ,a schematic , components list and the finished program as soon as possible.
So this is how it looks at this time, the TC i/f is connected to the right of the micro USB connector.
oh yeah..., I still use a DT006 parallel cable for ISP