How to Use Diode As a Heat Sensor Circuit

Are you interested about making a heat sensor circuit using a rectifier diode ? If so, you have come to the right place. In this blog post, we will discuss the basics of creating a heat sensor circuit that is both accurate and sensitive. The main thing is that, we will make this circuit using a cheap rectifier diode.

A diode is a semiconductor device that allows current to flow in only one direction. When a diode is subjected to heat, its electrical properties change. Specifically, the forward voltage drop across the diode decreases as the temperature increases.

This change in voltage drop can be used to detect changes in temperature and to measure the temperature of a device or environment. In other words, a diode can be used as a heat sensor.

To use a diode as a heat sensor, the diode is connected in series with a resistor and a voltage source. The voltage drop across the resistor is measured and used to calculate the temperature of the diode.

There are many types of diodes available, and the sensitivity of the diode to temperature changes can vary depending on the type and manufacturer. Additionally, the accuracy of temperature measurements using a diode can be affected by factors such as ambient temperature, thermal resistance, and thermal time constant.

Overall, while a diode can be used as a heat sensor, it may not be the most accurate or precise method of temperature measurement. Other types of temperature sensors, such as thermocouples or resistance temperature detectors, may be better suited for certain applications.

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

When it comes to creating a heat sensor using a rectifier diode, it’s important to have the right components in your list. A heat sensor can be used for a variety of applications such as measuring temperature, controlling cooling systems. In this article, we’ll discuss some essential components that should be included in your heat sensor component list

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

Component list:

1. PCB – made by JLCPCB

2. Rectifier Diode

3. LED – 5mm

5. Resistor – 27 KΩ

6. Transistor - 13001

7. Capacitor - 100µf/ 25v

8. Power Source – DC 3.7 v

The 13001 is an NPN Transistor commonly used in low power amplifier circuits. The Transistor can provide a maximum gain of 40 to 80.

The transistor also has a high collector current of up to 600mA and a decent collector-emitter voltage of 400V and the base trigger voltage is only 9V.

13001 NPN Epitaxial Silicon Transistor Features Collector-Emitter Voltage: VCE O= 400V Collector Dissipation: PC(max)= 1000mW TO-126 Absolute Maximum Ratin gs (TA=25oC) Characteristic Collector-B ase Voltage Collector-Emitter Voltage E mitter-Base Voltage Collector Current C ollector Dissipation Junction Temperatu.

•        Continuous Collector Current: 100mA
•        Collector Emitter Voltage: 400V
•        Collector Base Voltage: 400V
•        Base trigger voltage: 7V
•        Maximum DC current Gain: 80
•        Package: TO-92

•        Avalanche diodes, to protect circuits from high voltage surges
•        Zener diodes, to regulate voltage
•        Varactor diodes, to electronically tune TV & radio receivers
•        Light-emitting diodes (LED), to produce light
•        Tunnel diodes, to generate radio-frequency oscillations

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. 

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

To make this circuit, 1st we connect resistor with transistor. We connect 27 KΩ resistors with Base leg of transistor. Then connect it's other terminal with 100µf/25v capacitor positive leg. Then connect capacitor negative leg with transistor Emitter leg.

We utilize JLCPCB https://jlcpcb.com/RTA to printout our PCB.

Now connect LED negative leg with transistor collector leg. Then connect LED positive leg with rectifier diode positive leg and connect rectifier diode negative leg with 100µf/25v capacitor positive leg.

To use this circuit, now we need to connect 3.7v power source with the circuit. We connect this power source positive terminal with positive leg of diode and LED and connect power source negative terminal with Emitter leg of transistor.

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.

Our circuit is completely ready for use now. We need to power switch ON and make heat on rectifier diode, then the LED light will glow. When the heat decrease from diode, then the led light will off. Again make heat on diode, then the LED light will glow again.

Again thanks to JLCPCB for best quality PCBs.

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.

To order your SMT PCBs, visit JLCPCB.

1.     Drag and drop SMT PCBs file on site.

2.     Choose your PCBs color and quantity.

3.     To free SMT assembly for your PCB click on “SMT Assembly” button and then confirm.

4.     Add your BOM file and CPL file.

5.     Place your order click on “Save to Cart” button.

6.     Confirm your shipping address and shipping method.

7.     Pay your payment

8.     Wait for confirmation mail.

9.     For SMT Service, Click here.

JLCPCB supported all shipping method can be seen below.

Estimated Delivery Time

• DHL International Express 3-5 business days
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• S.F Express (Standard) 5-8 business days
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• PayPal
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To confirm your order, pay your payment. Then accept PayPal, Credit/Debit Card, and Prepaid Wire Transfer. To manufacture your PCBs, it’ll take about 2 days. DHL will be fastest shipping method to arrive your ordered PCBs at your location.

All PCBs were well packed and quality was really good.

Thanks to JLCPCB for best quality PCBs.