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Registered Member #3637
Joined: Fri Jan 21 2011, 11:07PM
Location: Buffalo, NY
Posts: 1068
I'm working on a backyard foundry... and being the electrical minded person I am, I thought of ways of overcomplicating it.
How would I make it so the blower, which feeds to charcoal, can be cycled to stay at a rough certain temperature?
Like, a thermocouple/temperature sensor could be placed in the heap, and then once lit, the blower could then could be PWM'ed to allow for a variety of different temperatures, rather than just "on". (it's a 120 v AC blower)
Would I be able to do this with just some op-amp magic + a PWM like a KA7500 or KA3525? Or would I need a full microcontroller? If op amps, I haven't the slightest idea where to begin, and microcontrollers are out of the question.
Registered Member #3637
Joined: Fri Jan 21 2011, 11:07PM
Location: Buffalo, NY
Posts: 1068
well, wait, I guess I could use an SCR, like how they use in dimmers, but... how would I digitize the controls for the SCR? And I don't want to spend any money on this, so buying something is sort of out of the question. I already have a thermocouple from a water heater, and a bunch of parts I can use. Including SCR's.
Registered Member #162
Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140
If you use a simple system (such as a temperature switch controlling the fan) you will have to have a long time constant in the control system as the temperature change would lag considerably behind the fan control. A commercial temperature controller can be bought for around £50 ($80) which would incorporate PID control. Otherwise you would probably be better off with a light dimmer and a thermometer.
Registered Member #242
Joined: Thu Feb 23 2006, 11:37PM
Location: Erie PA
Posts: 210
Steve Conner has a "solid-state variac" design that i had borrowed in the past, I modified it for to use fiberoptics for the control. The SCR control: I think I used 47k for R11 but I'm not positive. The SCRs This has the sync signal generation
Registered Member #509
Joined: Sat Feb 10 2007, 07:02AM
Location:
Posts: 329
Sulaiman wrote ...
If you use a simple system (such as a temperature switch controlling the fan) you will have to have a long time constant in the control system as the temperature change would lag considerably behind the fan control. A commercial temperature controller can be bought for around £50 ($80) which would incorporate PID control. Otherwise you would probably be better off with a light dimmer and a thermometer.
+1 to PID get on omega.com and go hog wild ;) You can pick up thermocouples and a PID controller with a thermocouple input. You can filter down the PID controllers, thermocouple input, and output of your choice.
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How could I make a simple feedback temperature system?
