Heat sensing circuit with timer and thermistor

[vanitapatil]

hello sir,
we r doing heat sensing ckt ,,, using thermistor , pleae tel us wt triggering pulse to connect d thermistor..... if u have any heat sensing circuit please give ...
thank u,

 

[chuckey]

Re: heat sensing circuit

Most thermistors are a resistor that has been specially made to change its value with temperature. The normal way of using them is to feed the thermistor by a high value resistor from a DC supply (high value resistor= low current, so keeps thermistor cool) and measuring the voltage drop across it. - no pulses.
Frank

 

[alexan_e]

Re: heat sensing circuit

Also note that
"Thermistors can be classified into two types, depending on the sign of k. If k is positive, the resistance increases with increasing temperature, and the device is called a positive temperature coefficient (PTC) thermistor, or posistor. If k is negative, the resistance decreases with increasing temperature, and the device is called a negative temperature coefficient (NTC) thermistor."

Thermistor - Wikipedia, the free encyclopedia

Alex

 

[vanitapatil]

Re: heat sensing circuit

sir ,if possible send one heat sensing circuit using 555 timer and thermistor

 

[alexan_e]

Re: heat sensing circuit

The Circuit Diagram of Fire Alarm | schematicwiring.com

Alex

---------- Post added at 18:51 ---------- Previous post was at 18:47 ----------

Here is another link
555Timer High Temperature Monitor for Fridge

Alex