Tuesday, August 26, 2014
Simple Heat Sensor Wiring diagram Schematic
This simple heat sensor schema could senses heat from various electronics device like computer, amplifier etc. and generate warning alarm. It could senses heat from environment also, but here I mention “electronics device” because it is being using mostly in electronic device to protect them from overheat.
Thermistor, 110 Ohms:
| Fig-2: 110 Ohms Thermistor |
As it is a heat sensor schema, here a thermistor is used as a heat sensor. It is a thermal measurement device and has a variety of usages including temperature sensor/ heat sensor. The thermistor used in this schema is a NTC (Negative Temperature Coefficient) type thermistor. When temperature increases, its resistance goes decrease. Therefore, NTC thermistor’s resistances are inverse of temperature.
Circuit Description:
You have seen, in this simple schema diagram of heat sensor, a few number of components is used including a BC548 transistor, a 110 ohms thermistor etc.- BC548: BC548 is a TO-92 type NPN transistor, as its alternative you can use 2N2222, BC238, BC548, BC168, BC183 etc. they all have almost same characteristic.
- 110 Ohms Thermistor: A 110 Ohms thermistor is used to detecting heat. I have told already about it.
- Buzzer: A buzzer is used with +9V and collector of transistor. When the temperature/ heat exceeds a certain level then it make an alarm.
- 4.7V Zener diode: It is used to limit the emitter current of BC548.
- 9V Battery: A 9V battery is used as a single power source.
- R1, R2: A 3.3K 1/4w resistor is used as R1 and 100 ohms 1/4w as R2.
- Switch: Here in this schema the switch used is a simple SPST switch. You can either use the switch or not, choice is yours. It is not mandatory.
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