Temperature control circuit

Thread Starter

Andrewlapham

Joined Aug 29, 2017
32
Hey, I'm rebuilding a magnetic stirer i bought from aliexpress. On inspection it was just a dinky little transformer with a discreet bridge rectifier running into a very basic lm315 circuit to adjust the speed of the motor. I've completely ripped out everything and rebuild it. I'm just stuck on the heating element. The element itself is straight across the mains (240v) It measured around 370ohms, 155w. I would like to make the heating output adjustable but don't know where to start, any ideas?
 

MisterBill2

Joined Jan 23, 2018
8,231
The lamp dimmer will serve quite well as a heat control, but if the goal is to control the temperature to some setpoint there also need to be a temperature sensor and a feedback arrangement to adjust the heat output to hold some set temperature. With the dimmer control the user adjusting the setting is the feedback portion.
 

Reloadron

Joined Jan 15, 2015
5,888
I would like to make the heating output adjustable but don't know where to start, any ideas?
Do you want control as in having a set point or do you just want simple adjustable? This can get as simple or complicated as you would like it to be. Do you want to use the existing heating element or would you like to replace it?

Ron
 

Thread Starter

Andrewlapham

Joined Aug 29, 2017
32
Do you want control as in having a set point or do you just want simple adjustable? This can get as simple or complicated as you would like it to be. Do you want to use the existing heating element or would you like to replace it?

Ron
The existing element is fine, yeah I dont want to go too deep into the rabbit hole. Plain old adjustable would be fine.
 

MisterBill2

Joined Jan 23, 2018
8,231
OK, "Plain Old Adjustable" means that a classic dimmer control such as used for the past 20 years will work. And there is also an option of a smaller package, the dimmer used in some pole-lamps and similar floor standing lamps. That control has the advantage of a much more convenient form, mounting with a single hole about 3/8 inch diameter. But those may not be available for use with 240 volt mains.
 
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