Analysis of the schematic diagram of CMOS circuit with electric soldering iron
When soldering CMOS circuits, due to the extremely high input impedance, the induced electricity on the soldering iron tip is sufficient to break down the CMOS circuit. When soldering CMOS circuits, enthusiasts need to connect the soldering iron tip to the ground. Unplug the power plug before welding, which is obviously inconvenient. Especially when many solder joints need to be welded at once, frequent insertion and removal processes are particularly inconvenient. Additionally. Sometimes the temperature is insufficient when using a 20W soldering iron, and if using a soldering iron with more than 20W, there is always a suspicion that the temperature is too high. It is convenient to adjust the temperature of the soldering iron and disconnect the power supply.
The circuit principle consists of a transistor switch circuit and a thyristor voltage regulating circuit. For now, only a brief explanation will be given on the manufacturing issues: button AN should be installed on the soldering iron handle and should be easily pressed during soldering. The back of the circuit board is bonded to the soldering iron handle with epoxy resin, and the two poles of the leads are shielded with thin wires. The two poles are soldered to the two poles of the circuit board, and then the outer circumference of the conductive rubber contacts is glued to the board with neoprene. The length of the shielding wire should be the same as that of the soldering iron power cord, and both should be placed together in a soft plastic sleeve.
Connect the two ends of the button cable with a coaxial plug or banana plug, and use socket CZ2 to match it. Two sets of conversion contact relays should be used, and a small AC voltmeter should be connected in parallel to the two poles of socket CZ1 for temperature control parameters. If not available, a scale can also be engraved around the W axis of the potentiometer to roughly grasp the temperature of the soldering iron. The components in the circuit are selected according to the diagram without any special requirements.
When using, plug the soldering iron power plug and button plug into their respective sockets, plug in the power, and adjust the temperature according to the welding requirements. When welding, before the soldering iron tip touches the solder joint, press the button with your finger and hear the suction sound of the relay. The surface of the soldering iron tip is no longer charged, so you can weld with confidence. When leaving the solder joint, lift your finger and turn on the soldering iron to heat up.
