Temp Controller

[wreck-it-steve]

Hi,

I am looking for some sort of temperature controller with ONE remote probe that will activate a relay when over the set temp and activate another relay when under the set temp....

Any ideas?

Thanks!

 

[Porque223]

If you build it yourself with IC comparators it's $20 in parts and a weekend of assembly & debug. You might be able to find a kit.

You want a dead zone, hysteresis, around the setpoint to prevent problems. +/- one degree may do it.

 

[THRIPSTER]

Have a look at the kits available in Maplins. Most relays have change over contacts meaning that when energised, one pair of contacts will be closed and when un-energised another pair of contacts will be closed. As Pork says, you could also build a simple circuit.

Regards

 

[ericmark]

RS Components and Farnell them do a host of controllers that will do the job. However some are rather expensive and also many require fitting into a cabinet.

The amount of leeway between on and off is what ramps up the price. A simple hot water tank thermostat is cheap and since you don't give limits it is impossible to say what will work.

There are kits for extra low voltage from Maplin and like.

We considered if there were more than 5 items requiring timers and temperature control within a machine then likely cheaper to use a PLC with 5 - 20 ma senders than stand alone units these will allow you to select range.

However your own skill is also a limiting factor programming a PLC is not really DIY stuff. I have worked with some rather complex systems like pre-heating and stress relief where the thermocouples were welded onto the metal. Your question is far too open for a real answer to be given.

Note to Porque223 this is a UK forum dollars mean nothing and I may know how to wire and use a 741 opamp but unlikely many DIY guys will even know what an opamp is.

 

[mikely]

A simple temperature switch module (note will only switch 24V):
http://www.velleman.co.uk/contents/en-uk/d51_Controllers.html

Or something a bit more advanced:
http://www.conrad-uk.com/ce/en/product/198545/Conrad-1004-FOX-Temperature-Controller

Or a version with two independently controlled outputs:
http://www.conrad-uk.com/ce/en/product/198558/Conrad-D1004-FOX-Temperature-Controller

 

[slup]

Do a google search for STC-1000 - many fishkeepers use them for aquarium control. Sub £20, has remote probe and separate heat / cool contacts.

Hysteresis is adjustable

 

[Spark123]

What temperature range do you need? How much have you got to spend? What is it for? Do you need two set points or will one with change over contacts do?