Saturday, March 12, 2011

Temperature Controlled Relays Circuit

This circuit energizes the relay when the temperature rises above the preset level. The value of the thermistor is not critical. The important thing is the voltage on pins 5 & 6. Any value thermistor should work satisfactorily. But you may need to change the value of R1 - to achieve the desired range of adjustment.
Temperature Controlled Relays CircuitTemperature Controlled Relays Circuit

The Circuit operating temperature will adjust from about 5C to 75C (41F to 167F). However - this wide range makes the adjustment coarse. You can improve control by reducing the value of the pot and increasing the value of R2. Use R2 to take you close to the desired temperature - and use the reduced value pot to make the fine adjustment.

The relay is actually controlled by the voltage on pins 5 & 6. So - by changing the value of R2 - you can extend the range in either direction. Increasing the value of R2 - will give access to lower temperatures. And - reducing the value of R2 - will give access to higher temperatures.



This Circuit From: www.zen22142.zen.co.uk

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