A 30W electric soldering iron feels like it needs to be heated for a long time during the welding process of large components, which can easily damage the welded components.
So after thinking for a long time, I came up with a way to avoid the occurrence of the above situation. Firstly, the temperature regulating circuit of the electric soldering iron was drawn, as shown in the figure. The components are actually very simple, including a multi throw switch, three 400V/4.7uF capacitors, and three 1N4001 diodes and wires. There is one three-phase plug and one exposed socket, and some friends may ask where there is a three-phase soldering iron? Actually, this is a preparation to add another important feature. That is grounding, because the electric soldering iron has induced electricity sufficient to cause the integrated circuit to break down, so grounding is necessary to release these charges.
We also need a plastic insulation box, which can be replaced by the plastic box of the damaged fluorescent lamp rectifier. Of course, other plastic boxes can also be used. Weld the original component onto the switch according to my circuit diagram. Then connect the A and B terminals to the live and zero wires of the plug, and connect the C and D terminals to the live and zero wires of the socket. Screw a copper wire onto the root heat dissipation hole of the iron steel jacket, and then connect the wire to the ground wire end of the three-phase plug. This completes the work.
When the selection switch is connected to 1, a diode is connected in series in the circuit, which is equivalent to a half wave rectifier circuit. At this time, the soldering iron only uses the positive half wave of AC power to do work. It is equivalent to reducing the power of the electric soldering iron to only 70 percent of the usual power, and with temperature loss, the heat generation is only 60 percent of the original. It is precisely used for ironing and waiting for insulation during debugging, without causing oxidation of the electric soldering iron head.
When the switch is selected to 2, it is normal power and suitable for welding small components. When the switch is selected to 3, although a diode is also connected in series to form a half wave rectifier circuit, we have connected a 400V/4.7uF capacitor in parallel on the load of the soldering iron. In this way, the rectified direct current is then boosted to 280V through a capacitor to supply the soldering iron for use. But as the voltage increases, the power of the electric soldering iron also increases by 30 percent , making it much more convenient to weld large components at high temperatures. When the switch is connected to 4, it is also a half wave rectification, but with two capacitors boosting the voltage, there will be a voltage of 300V, and the temperature will be even higher. This creates a multi-level temperature adjustment electric soldering iron.
