Many Electronic circuit projects in simple ways of learning

2 ideas of Car overheat alarm circuit

This is a circuit sound alarm when an engine start spreading the heat. Although every car will have a temperature gauge. But in some cars. May be no warning if the engine is overloaded with heat. Or the driver may not have noticed the temperature gauge can cause problems.

The working of circuit

The circuit in Figure 1 When the temperature of the engine increases. The resistance of the thermistor decreases. Thermistor is connected to R1 for divide the voltage of the power supply to pin 2 of an op-amp IC1-LM741. This voltage will decrease as the temperature rises, by at VR1-100K is used to adjust a reference voltage at pin 3 of IC1. When a voltage at pin 2 lower than pin 3, IC1 will be switch close makes has voltage at output pin 6 to send to IC2.

The IC2 is connected as an astable multivibrator to the sound signal generator circuit Temperature level to cause the sound can be adjusted with VR1. The VR2 will determine the frequency of the sound. Thermistor used in this circuit, as beads. Has a negative temperature coefficient.(NTC) Thermistors are devices that are heat resistant and can pass it quickly. Suitable for adoption. Used in this circuit currents up to 10 mA.

The parts list.
R1- 4.7K______________________1 pcs.
R2-22K_______________________1 pcs
RTH1- Thermistor NTC type_________1 pcs.
VR1,VR2 Variable resistors _100K____2 pcs.

C1-0.01uF 63V Polyester Capacitor _____________1 pcs.
C2-100uF 16V Electrolytic Capacitor__________1 pcs.
The semiconductor
ZD1- zener diode 5.1 volts______________1 pcs.
IC1- LM741 op-amp_________________1 pcs.
IC2- NE555 timer________________1 pcs.

Loudspeaker 8 ohm____________________1 pcs

Automobile heat Warning with LED

This circuit sets up in its automobile will perform to warn give testimony know before your car is will born the heat too much. By use main part electronic be IC 741 and Thermistors. By have LED Flasher with usual rate , when the temperature arrives at location value keeps with before VR1. When the temperature increases continuously LED as a result stick bright forever. By control checking temperature has with VR2. This circuit gives with power supply of an automobile has normally for the frequency of winking can fix with C1. A friend can see the detail adds in the circuit.

Warn the heat in an automobile

Related Posts

JLCPCB - Only $2 for PCB Protytpe(Any Color)

With 600,000+ Customers Worldwide, 10,000+ PCB Orders Per Day

Up to $20 shipping discount on first order now:

This Post Has 9 Comments

  1. what is the working of zener diode in this circuit?

  2. Hi – great idea, Just wondering what sensor is required, where it is positioned and where the sensor input is fed into the circuit,



  3. can ilook for the whole project

  4. Can you please give a detailed and clear explanation of the above circuit.. Also specify why Zener diode has been placed… Hoping for an early reply

  5. This circuit is wrong. It gives buzzer for every temperature. a transistor has to be used so that it switches on only for higher temperatures.

  6. This circuit is blowing buzzer at every temperature. please tell me how it will work properly

  7. It is giving buzzer at every temperature…

  8. please give me brief explanation about working principle of this circuit? especially how current reach from DC battery to alarm?

  9. Hi,Abebe Alem
    It should work well. But I can not confirm. Because I have not actually tried it.
    If you can wait My son will create for you.

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Close Menu