Build Our Own Solder Fume Extractor Circuit

Soldering make bad smoke which is not good for health.

So every work table need good smoke remover.

To Build Our Own Solder Fume Extractor Circuit uses few easy parts to remove bad smoke.

It uses BC547 transistor, small DC fan, preset resistor, capacitor and NTC thermistor to make air clean and safe.

NTC thermistor is main part as it feel heat from soldering.

When hot thermistor resistance goes down and fan turns ON and pull out smoke.

Preset resistor control how sensitive thermistor is so to make fan turn ON at right time.

Capacitor stop shaking in circuit and resistor help transistor work steady.

BC547 transistor work like switch for fan.

Fan can run with 5V or 9V which depend on power we give.

Power come from 9V battery so it is easy to move and use.

This circuit help soldering be more safe.

Also it is good for beginners to learn about thermistor, transistor switch and about basic circuit.

It is easy to make and a good tool for any electronics table.

Circuit Working:

Parts List:

This solder smoke remover circuit is easy to make.

Put NTC thermistor close to soldering iron tip on stand.

Use preset VR1 to adjust how sensitive it is.

When there is no heat then thermistor resistance is 10k.

When it gets hot the resistance goes down and depends on temperature.

This setup work like voltage divider and shows voltage change when thermistor resistance changes.

If we want fixed trigger point then we can change VR1 with fixed resistor but we need calculation.

Resistor R1 and Capacitor C1 connect divider output to base of transistor T1.

C1 makes voltage goes up and down slowly but not sudden.

When base voltage goes over 0.7V, transistor T1 turns ON which let fan get power from ground.

More voltage means more fan speed.

Put fan behind soldering iron, air suction side face to iron which is to pull the smoke.

To catch smoke better put something absorbent in front of a fan.

Formulas:

Useful Formulas for Making Solder Smoke Remover Circuit:

1. Thermistor Resistance:

RT = R0 × e^(B/T − B/T0)

where,

• RT is the thermistor resistance at temp T
• R0 is the resistance at reference temp T0
• B is the thermistor beta constant
• T is the temp in Kelvin

2. Voltage Divider to get base voltage of T1:

VB = (Rpreset / (RNTC + Rpreset)) × Vsupply

where,

• VB is the base voltage
• Rpreset is the preset resistor
• RNTC is the thermistor resistance
• Vsupply is the 9V

3. Transistor Base Current:

IB = (VB − VBE) / R1

where,

• VBE is around 0.7V for silicon transistor
• R1 is the base resistor

4. Fan Collector Current:

IC = β × IB

where,

• β is the transistor current gain
• IC is the current to fan

These formulas help us build the solder smoke extractor circuit step by step.

How to Build:

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

• Connect collector of T1 to one wire of DC fan.
• Connect other fan wire to +9V battery.
• Connect base of T1 between 10k thermistor and 1k preset using 100Ω resistor R1.
• Connect emitter of T1 to GND.
• Connect positive side of 10µF capacitor C1 to point where NTC, preset and R1 meet.
• Connect one leg of 1k preset to junction of NTC and R1 and other leg to GND.
• Connect one leg of 10k NTC thermistor to +9V and other leg to point between preset and R1.

Conclusion:

This Build Our Own Solder Fume Extractor Circuit is good for removing harmful fumes while soldering.

NTC thermistor feels heat near soldering iron and changes fan speed.

We can adjust sensitivity with preset or fix it with resistor.

If fan is placed right and sponge used to catch smoke then this design makes soldering more safe and comfortable.

This circuit is good for any soldering workspace.

References:

Are solder fumes bad for me?