Temperature limit Relay

Posted on Mar 22, 2013

This circuit, is basically a resistance ? sensing window switch, except that the ?resistor? takes the form of an NTC thermistor and the circuit thus responds to temperature. TH1 must have a resistance in the range 500ohm - 9Kohm. RV1 is used to set half ? supply volts on the RV1 ? TH1 junction at the ?mean? temperature.

Temperature limit Relay
Click here to download the full size of the above Circuit.

Part List R1=4.7Kohm TH1=NTC thermistor 500ohm.....9Kohm Q2=BC214L R2=2.2Kohm D1-2=1N4148 RL1=12V Relay >120ohm RV1-2-3=10Kohm pot. D3=1N4001

Leave Comment

characters left:

New Circuits



Popular Circuits

14MHz SSB 10mW transceiver
Arduino powered GLCD (Graphic LCD)
Flash Slave Trigger
fm radio ic tda7000 schematic
home built laser system
Low Noise Microphone Preamplifier Circuit
Crystal radio schematics
Color Sensor from a Reversed LED and Op Amp
Automatic light control circuit curtains