Build Your Own Solder Fume Extractor Circuit

Since soldering may release toxic vapors that are bad for your health, every workstation needs to have a good smoke extraction system.

This simple soldering smoke extractor circuit uses a few easily accessible electrical parts to reduce harmful vapors.

This circuit provides a useful way to keep a workplace that is safer and cleaner by using a BC547 transistor, a tiny DC fan, a preset resistor, a capacitor, and an NTC thermistor.

As a temperature sensor, the NTC thermistor is the central part of this circuit.

The thermistors resistance lowers when heat is produced during the soldering process, which causes the fan to turn on and efficiently remove smoke.

The thermistors sensitivity is adjusted by the preset resistor enabling the best possible fan activation.

The capacitor helps to even out any oscillations in the circuit, while a resistor guarantees the transistor operates steadily.

The DC fan is controlled by the BC547 transistor, which functions as a switch.

Depending on the available power source, the DC fan can run at 5V or 9V.

Lastly, the power supply is a 9V battery, which guarantees mobility and user friendliness.

In addition to improving soldering safety, this circuit is a great project for newbies wishing to learn about thermistors, transistor switching, and fundamental electrical design.

This smoke extractor circuit is a useful addition to any electronics workbench since it has basic components and an easy to understand function.

Circuit Working:

Parts List:

This soldering smoke extractor circuit is quite easy to create.

On the stand, the NTC Thermistor needs to be positioned near to the tip of the soldering iron.

The sensitivity level is adjusted via the preset VR1.

When there is no external heat, the maximum resistance of the NTC Thermistor is 10k.

As it monitors temperature, the resistance reduces dependent on the temperature level.

With this voltage divider configuration, we can identify voltage differences brought on by variations in the resistance of the thermistor.

With a particular triggering point, you can swap out the preset VR1 with a fixed value resistor, although this will need some math.

Via Resistor R1 and Capacitor C1, the voltage dividers output is connected to the base of transistor T1.

Capacitor C1 contributes to a gradual rise and fall in voltage.

Transistor T1 begins to conduct when its base voltage rises over 0.7V, which permits the ground supply to flow to the fan.

The fan speed is maximized as the conductivity between the collector and emitter rises.

Put the fan behind the soldering iron, with the air suction side facing the soldering iron, to remove smoke from it.

To capture the smoke, place an absorbent object in front of the fan.

Formulas:

Below are some relevant formulas for Building Your Own Solder Fume Extractor Circuit:

Thermistor Resistance Calculation:

R_T​ = R₀ ​x e^{(BT​ − BT_0​)}

where,

• RT​ is the resistance of the thermistor at temperature T
• R0​ is the resistance at reference temperature T0
• B is the beta constant of the thermistor
• T is the temperature in kelvin

Voltage Divider Formula:

The voltage divider formula may be used to find the voltage at T1s base:

V_B​ = R_preset​ / R_NTC​ + R_preset​​ × V_supply​

where,

• VB​ is the base voltage
• Rpreset is the resistance of the preset
• RNTC​ is the resistance of the NTC thermistor
• Vsupply is the supply voltage 9V

Transistor Biasing:

To make sure the transistor functions in the active zone, you must ascertain the base current IB:

I_B​ = V_B​−V_BE​​ / R_1​

where,

• VBE​ is typically around 0.7V for silicon transistors.

DC Fan Current Calculation:

Upon activation of the transistor, the collector current IC, which powers the fan, may be roughly represented as follows:

I_C​ = β x I_B​

where,

• β is the current gain of the transistor.

You should be able to build an solder fume extractor circuit by according to these instructions.

How to Build:

For Building Your Own Solder Fume Extractor Circuit follow the below mentioned steps:

• Assemble all the components as shown in the above circuit diagram.
• Connect collector of transistor T1 to one wire of DC Fan and the other wire of DC fan to 9V positive supply battery.
• Connect base of transistor T1 between 10k thermistor and preset 1k through resistor R1 100Ω.
• Connect emitter of transistor T1 to GND .
• Connect the positive terminal of 10uF C1 capacitor to the junction of the NTC and the preset and also to one end of R1 resistor
• Connect the one terminal of preset 1k with the junction of NTC and resistor R1 and other terminal of preset to GND.
• Connect NTC 10k thermistor one terminal to 9V positive supply battery and other end to junction of 1k preset and resistor R1.

Conclusion:

To conclude, this solder smoke extractor circuit offers a practical means of controlling the fumes released during the soldering process.

The NTC Thermistor can precisely sense temperature changes and modify the fan speed by placing it close to the soldering iron.

Because of its adaptability, the sensitivity may be fixed or adjusted.

This circuit improves comfort and safety when the fan is positioned properly and has a sponge to collect smoke, making it a useful addition to any soldering setup.

References:

Are solder fumes bad for me?