Soldering in electronics is analogous to fixing of a component using glue. It is actually a general phenomenon in the field of electronics which involves fixing of electronic components into a special board called PCB with the help of instruments like soldering iron and electrical solder commonly called as ‘Solder wire’.
While soldering we all face problem of toxic fumes. These fumes are of lead solder wire and flux. Combinedly, these fumes are highly toxic if excess amount is inhaled. In order to solve this problem, here we had designed a simple circuit called solder fume extractor using an op-amp IC which removes fumes from the soldering area. The circuit posted here is of automatic type which runs exhaust fan during soldering and stops exhaust fan when soldering iron is kept on soldering stand.
Circuit Description of Solder Fumes Extractor
The Circuit of solder fume extractor shown in figure 1, designed using op-amp CA3130, two NPN transistors and few other passive component. For fumes removing we had used a small 12V DC exhaust fan.
For automation of the projects solder fumes extractor we have used a sensor called piezo sensor (PZ1). The sensor PZ1 generate voltage when heat is detected (heat generates stress in it). Thus, we had attached a heat sink with piezo sensor PZ1. The PZ1 is connected to two inputs (inverting and non-inverting) of IC1 as shown in figure 1.
The heat sink connected to piezo sensor PZ1 is kept near to the soldering stand. For better description, we have divided the working of solder fumes extractor circuit into two cases.
CASE I: When soldering iron is on soldering stand, the heat from soldering built stress on piezo sensor as a result voltage of 1V generates to the piezo sensor which activates op-amp and the output of op-amp become high. The high output of op-amp turns transistor T1 ON and transistor T2 OFF as a result fan connected to the circuit is switched OFF.
CASE II: when soldering iron is taken out from soldering stand for solder a joint, no stress is built on piezo sensor due to heat as a result the output of op-amp drive transistor T1 to off state, but transistor T2 start to conduct which further switch on the fan which removes fumes from soldering.
Null adjustment of IC1 is adjustment by variable resistor VR1. When output of IC1 is momentarily low the capacitor C1 makes transistor T1 on and is discharge through resistor R1 when output of IC1 becomes low.
PARTS LIST OF SOLDER FUMES EXTRACTOR USING OP-AMP
|Resistors (all ¼-watt, ± 5% Carbon)|
|R1 = 100 KΩ
R2 = 100 Ω
R3, R4 = 1 KΩ
VR1 = 10 KΩ
|C1 = 470 µF, 35V (Electrolytic Capacitors)|
|IC1 = CA3130 op-amp
T1 = BC547 (NPN transistor)
T2 = BD139 (NPN transistor)
D1 = 1N4007 (general purpose rectifier diode)
LED1 = 3mm any color LED
|PZ1 = Piezo sensor
SW1 = ON/OFF Switch
12V DC Exhaust Fan
Batt. = 12V, 7Ah Battery