• Skip to main content
  • Skip to primary sidebar

Making Easy Circuits

Learn and build electronic circuits

You are here: Home / Indicators / Heatsink Temperature Monitor Circuit

Heatsink Temperature Monitor Circuit

Last Updated on April 8, 2020 by Admin Leave a Comment

Heatsinks are a necessary inclusion in circuits which are rated to work with high wattage and high current supplies. The heatsink is installed on devices so that it draws the excess heat from the power devices, preventing their malfunction.

The convention is to use the maximum allowed temperature for the silicon chip as the reference for the rating of the heat sink. However, Tthis is not a very reliable or the recommended method.

The heatsink indicator circuit here monitors the heatsink temperature constantly. The green LED remains on when the temperature is below 50-60°C.

heatsink monitor
Relay contacts associated with Re can be used for disconnecting power to the circuit which is being monitored, when the the heatsink temperature reaches the maximum level

Above 50-60°C till 70-80°C, the yellow or orange LED stays lit and above that temperature, the red LED lights up. You can also add a relay to disconnect the load when it heats up.

The basic design of the heatsink temperature monitor employs a window comparator. The control voltage is provided by sensor D1 and it rises 10mV per 1°C rise in temperature.

When the sensor voltage is below that the wipers potentials of P1 and P2, op amps A1 and A2 have low outputs and D2 lights up.

If the voltage across D1 is greater than that at the wiper of P1 but less than that at the wiper of P2, A2 has a high output, causing D2 to turn off and D3 to light up.

If the sensor voltage goes above that at the wiper of P2 too, both op amps register high outputs, causing D5 and transistor T1 to be turned on. Zener diode D4 is used to make sure that D5 still lights brightly and T1 conducts hard enough.

How to Calibrate

Calibration of the heatsink monitor circuit is done by putting the sensor in a tray of water along with a thermometer. Then heat the tray. P1 is set to the minimum resistance and P2 to the maximum.

The crossover point from green to yellow is set between 50-60°C with P1 and that from yellow to red is set between 70-80°C with P2. Then install the sensor into the heat sink permanently.

You'll also like:

  • 1.  Simple Burglar Deterrent Circuit
  • 2.  Temperature Meter Using Digital Multimeter
  • 3.  Coffee Temperature Indicator Circuit
  • 4.  Automatic LDR Switch Circuit with Flashing Lamp
  • 5.  Simple Crystal Tester Circuit
  • 6.  How to Build a Logic Level Indicator Circuit

About Admin

Hey friends, Thanks a bunch for stopping by this site! I am an engineer with a Bachelor of Engineering in Electronics and Telecommunication. One of my passions is gathering information from all sorts of electronics books and tutorials. I then take that information and compile it into a language that is super easy to understand. My goal is to make those complex electronics circuit concepts and technical terms much more accessible for all the new and budding electronics engineers out there. I can also design customized circuit diagrams as required by the users.
If you have any questions related to this field, please do not hesitate to drop a comment! I am always here and ready to help you out with any queries you might have. I cannot wait to hear from you!

Reader Interactions

Leave a Reply Cancel reply

Your email address will not be published. Required fields are marked *

Primary Sidebar

Categories

  • 3 Phase (4)
  • 8051 Microcontroller (1)
  • Arduino (11)
  • Audio and Amplifier (102)
  • Automation (8)
  • Battery Chargers (64)
  • Bicycle Projects (4)
  • Car and Motorcycle Projects (39)
  • Datasheets (10)
  • DIY Projects (5)
  • Electrical (15)
  • Free Energy (6)
  • Games Projects (2)
  • High Voltage (14)
  • Hobby Projects (30)
  • Household Circuits (2)
  • IC 555 Circuits (4)
  • Ignition Circuits (2)
  • Indicators (50)
  • Infrared (6)
  • Inverter Circuits (29)
  • Lights and Lamps (97)
  • Medical (8)
  • Meter and Tester Circuits (38)
  • Motor Driver (17)
  • New Circuits (56)
  • Oscillators (30)
  • Pets and Pests (5)
  • Power supply (81)
  • Protection Circuits (25)
  • PWM (8)
  • Remote Control (20)
  • Security and Alarm Circuit (48)
  • Sensors and Detectors (66)
  • Signal Processor (23)
  • Solar Controller Circuits (61)
  • SSR (3)
  • Temperature Controller (20)
  • Timer (25)
  • Transformerless (7)
  • Transmitters (12)
  • Tutorials (45)
  • UPS (2)
  • Voltage Regulators (57)
  • Water Sensor and Controller (29)
  • Home
  • Privacy Policy
  • Contact
  • Disclaimer
  • Copyright

© 2025 · Making Easy Circuits