Solution to the problem of temperature loss of constant temperature soldering iron
The constant temperature soldering iron adopts a high Curie temperature strip PTC constant temperature heating element inside, equipped with a fastening thermal conductive structure. The characteristics are superior to traditional electric heating wire soldering iron cores, with rapid heating, energy saving, reliable operation, long service life, and low cost. Low voltage PTC heating elements can be used in the field for easy maintenance work.
The common malfunction of a constant temperature soldering iron is temperature runaway, which results in the soldering iron's temperature being too high. On the one hand, it leads to high-temperature oxidation of the soldering iron tip (the solder is also oxidized at the same time); On the other hand, welding at high temperatures can also easily burn out electronic components. When the soldering iron works at high temperatures for a long time, it is also easy to cause damage to its internal circuit, resulting in permanent loss of control or even inability to use. During the fault inspection, it will be found that the sliding contact of the temperature regulating resistor R2 is oxidized and causes poor contact, which is equivalent to the temperature being adjusted to the maximum upper limit, resulting in a higher temperature of the soldering iron. There are two fundamental reasons for this: firstly, when the soldering iron is working, it transfers some heat to the handle of the soldering iron (inside the circuit), causing the temperature of the working environment of the circuit to increase. After a period of time, it is easy to cause oxidation of R2's moving contacts; The second issue is that the current limiting resistor R1 in the rectification and filtering circuit dissipates heat, causing an increase in the working environment temperature and easily leading to the oxidation of R2's moving contacts.
To prevent such faults from occurring, the following two methods of modifying the circuit are proposed:
(1) Replace adjustable resistor R2 with a fixed resistor: First adjust R2 to reach the optimal temperature point for normal use of the soldering iron, then measure the value of R2 and replace it with a fixed resistor.
(2) Transform rectifier circuit
