How to Make Heat Sensor Circuit

In this project, we are going to teach you making heat sensor circuit. A heat sensor circuit senses the heat from various electronic devices like amplifiers, computer, etc, and thus generates the warning alarm.

Heat sensors react to the change in temperature caused by fire or the other thing.

When the temperature rises above 135 degrees or 194 degrees, the heat sensor will send a signal to an alarm panel and trigger an alarm.

Temperature sensors are used in many electrical applications, from our refrigerators and freezers to help regulate and maintain cold temperatures as well as within stoves and ovens to ensure that they heat to the required levels for cooking, air confectioners/heaters.

Supplies

The article is being published in collaboration with JLCPCB. They supply high quality PCBs at a very reasonable price. They also can provide SMT circuit assembly.

The final circuit diagram and design can be seen above. We also thank to our sponsor JLCPCB (https://jlcpcb.com/RTA) for sponsoring us PCB for this project.

Thanks To JLCPCB.

$2 for 1-4 Layer PCBs.

Get SMT Coupons - https://jlcpcb.com/RTA

Component List

To make this polarity protection circuit, we might need some electronics component. Those component lists have to been given below.

Component List :

1. PCB – made by JLCPCB

2. NTC - 103

3. LED – 5mm

5. Resistor – 2.2 KΩ

6. Mosfet – IRF z44n

7. Heat Producer

8. Power Source – DC 12v

Heat Sensor Circuit Design

The Design of heat sensor circuit along with the PCB layout can be seen above. Power supply don’t included with the circuit. You can use any 12 battery for this project.

Schematic of Heat Sensor Circuit

The schematic of heat sensor circuit along with the PCB layout can be seen above.

Specification of NTC Thermistor

Resistance is 10K ± 1% at 25 degrees Centigrade.
B-value is 3950 ± 1%.
Its response time is very fast from 0.12 to 10s.
Dissipation factor δth is approximately 7.5mW/K.
The thermal cooling time constant is <= 20 Sec.
Temperature ranges from -55 °C to +200 °C.
Available terminals are two.
Linearity is exponential.
Its accuracy ranges from 0.05°C to 1.00°C.
The maximum tolerance is up to ±1.5% at –40°C & 150°C.
Its cost ranges from low to moderate.

Advantages of NTC Thermistor

The advantages of an NTC thermistor include the following.

They have High flexibility and sensitivity.
It can be used as a temperature sensor to detect temperature.
These thermistors provide high accuracy & interchangeability simultaneously.
NTC thermistors have high reliability, accuracy, good performance, good heat resistance, small volume, etc.
A wide range of tolerances & sizes is available.
As compared to other temperature-sensitive resistors, NTC thermistors have a main advantage like sensitivity.
These thermistors respond to even mild changes in temperature.
They can precisely detect a wave that is below a single degree within the temperature.

Disadvantages of NTC Thermistor

The disadvantages of NTC thermistors include the following.

NTC thermistors are very sensitive components so they can destroy the entire appliance once overheating occurs.
If this thermistor is damaged, then the dryer will not work at all.
These are specially made, so replacement is not possible.
While selecting an NTC thermistor, it is essential to verify the working point of the center temperature.
Applications
The applications of NTC thermistors include the following.
The NTC (negative temperature coefficient) thermistors can be used as resistance thermometers within extremely low-temperature measurements.
These are normally used in current digital thermostats.
These are very helpful in monitoring the temperature of the battery while they charging.
These thermistors are used in electronic circuits as current-limiting devices.
These can also be used as an alternative to a fuse.
NTC thermistor is used as temperature compensation devices.

Connect LED With PCB

To make this circuit, we need to make a series connection in these 4 led lights. Here series connection means, we connect one LED negative leg with another LED positive leg.

In this way, we will get two different terminals. One is negative and the other one is positive.

Connect Resistor and Mosfet With PCBS

We are using 2.2 KΩ resistor IRF z44n mosfet. We connect resistor with “Gate” and “Drain” leg of mosfet. Then we connect LED with mosfet.

We connect this LED negative leg with “Drain” leg of mosfet.

Soldering and Cleaning

Neat and perfect soldering is an important part for all kind of PCBs. Since soldering, you should remember that, there should not be any kind of short circuit connection. After soldering all leg, we cut-off the extra leg of all electronics component.

We also can use liquid PCB cleaner to clean the PCB board.

Connect Power Supply

For power supply, we are using DC 12v. You can use 12v battery or can use the power supply, that can provide DC 12v. Be careful about the power supply, because if you use more than DC-12v, then led light will blown away and the circuit may damage also.

Final Action

Our circuit, is now completely ready for use. Now just plug-in the power supply and make heat beside the thermistor. A few moment later, you will see that the LED blown up and when the thermistor got cool again the LED blown down.

Again thanks to JLCPCB for best quality PCBs.

Steps to Order PCBs From JLCPCB

If you complete design of your PCBs, then it is time to order PCBs. To order best quality PCBs, just visit JLCPCB and click on the “QUOTE NOW” button.

Since 2006, JLCPCB continuously driven to become more efficient and to reduce costs. They promise to offer customers the most economic PCBs forever. JLCPCB makes cheapest but top quality PCBs possibly because of scale effect, extremely high production efficiency and less manpower cost.

You can order minimum 5 pieces PCBs for only $2 costs.

To order PCBs, make your Gerber file. Then drag and drop the Gerber file on the following box.

Click on “Gerber Viewer” button you can check the PCBs design. Make sure everything is good, then choose color, quantity and order your PCBs at very reasonable prices.

If you are a new user, then you can order 10 pieces PCBs, costing only $2. To place your order click on “Save to Cart” button. Confirm your shipping address and shipping method.