I'm looking at the ATM90E26 or ADE7763
Home Made Kiln Controller
Posted 14 February 2017 - 05:02 PM
It has been a while since I got to dabble with electronics. Looking into automating a gas kiln. Found a ball valve + actuator that needs 0-10v signal sent for how open it is. After some googling I found this op-amp circuit for doing that exact job so set about making it.
Took me a few failed attemps (wired the 24v positive up from actuator up to my raspberry pi and killed it, same with chip) but once I made sure it was the right circuit it all works perfectly.
Realised I never posted the MAX31855 circuit so here is that one too.
Tested it out on the kiln today and it works a treat. Still lots more work for actually programming the thing to do sensible things.
Posted 15 February 2017 - 08:33 AM
Nice work Joel! I've have been too busy at work to look at my stuff but, hope to return to it shortly; I did buy some MAX chips to compare against the AD595; I like the pwm to voltage converter, thanks for posting the circuits.
Keep up the progress!
Posted 18 February 2017 - 02:47 PM
I've decided that doing my own kiln controller would be an interesting project, but too much of a distraction from making pots.
This was exacerbated by my (now ex) kiln controller deciding to overfire to about 1330 (in a kiln rated to 1300!). In the soak, when the elements came on, the temperature readout dropped so they stayed on till it got to the target of 1290, then cut out and the temperature readout immediately jumped up to 1330 and the kiln cooled down to 1285, then the elements came on and the temperature immediately dropped. I guess the elements were causing a voltage drop which then affected the temperature reading.
Kiln survived, though the stoneware in it started bloating as it was an oil spot glaze with a long soak, and a while until I noticed.
Anyway, I've found that the Bentrup TC507 controller does all I need and more, and a lot quicker to get in place than rolling my own. It can also be used to control a gas kiln if you have the right valves, though I just use electric. So I'm wiring it all in, including a couple of thyristors to replace the relays which should give a longer element life.
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