Heat sensor schematic with the 4060 ic.
Heat sensor circuit working.
It senses heat from electronic devices and gives a warning alarm.
Working of the circuit is simple when there is heat or increase in temperature to the level where it crosses the threshold set by pot then the collector current increase and led starts illuminating slowly.
This circuit utilize ntc negative temperature coefficient thermistor hence the resistance value of this device decrease when the temperature rises.
This simple circuit is easy to construct and test.
It is an ideal add on circuit to monitor heat in cd players amplifiers etc.
This will confirm that the pcm is attempting to turn on the heater circuit and all the wiring to and from the pcm are in working order.
If the o 2 sensor heater circuit s negative wire goes directly to ground look for a short to power problem.
First is the positively controlled type of circuit.
Usually the heater circuit in this case is controlled by a relay.
The easiest way to find out is to read the trouble code memory and check the value from the sensor to make sure it s a viable value.
The o 2 sensor s heater circuit is controlled in one of two ways.
Checks the o2 sensor heater circuit for the proper resistance to specifications.
You also note that before start testing the circuit first set the variable resistor.
Simple heat sensor circuit designed to give alert sound when the temperature reaches the desired threshold here we can adjust the temperature threshold level using variable resistor rv1.
Let us consider thermistor having 110 ohms and after heating its resistance value becomes 90 ohms.
The voltage across one resistor and the ratio of that resistor s value and the sum of resistances times the voltage across the series combination is equal.
It is used to detect the heat.
We can also use buzzer in place to led.
Remove the relay and retest the circuit.
Bc548 is an npn transistor to 92 type.
Then as per the potential divider circuit which is a pervasive concept namely voltage divider.
Common symptoms of a bad engine coolant sensor are overheating difficult starting conditions poor idle check engine light on and electric fans not working properly.
Tests the o2 sensor connector for the proper input voltage from the ecm for the heater circuit.
We can use other alternatives like 2n2222 bc168 bc238 bc183 etc.
In short the heater circuit which was originally designed to bring the sensor up to operating temperature has now taken on an even more important role.
Monitors o2 sensor data to see if the heater circuit is working.
