Soldering iron thermostatic temperature not controlled
Constant temperature soldering iron internal use of high Curie temperature strip PTC thermostatic heating element, equipped with fastened heat conduction structure. Characterised by its superiority over traditional hot-wire soldering iron cores, rapid heating, energy saving, reliable operation, long life and low cost. With low voltage PTC heating core can be used in the field, easy maintenance work.
Thermostatic soldering iron temperature out of control solutions
The common failure of constant temperature soldering iron is the temperature out of control, the result of which causes the temperature of the soldering iron to be too high. On the one hand, it leads to high temperature oxidation of soldering iron head (solder is also oxidised at the same time); on the other hand, it is easy to burn electronic components when soldering at high temperature. When the soldering iron long-term work at high temperatures, it is also easy to cause damage to its internal circuitry, resulting in permanent loss of control or even can not be used. In the fault check will be found in the temperature control resistor R2 sliding contacts are oxidised to produce poor contact phenomenon, which is equivalent to the temperature is adjusted to the maximum upper limit, and thus the temperature of the iron is high. The root cause of two points: one is the soldering iron work to the iron's handle (circuit built-in) to transfer part of the heat, so that the circuit working environment temperature increases. After a period of time it is easy to cause the oxidation of the dynamic contacts of R2; Secondly, the current limiting resistor R1 in the rectifier filter circuit dissipates the heat and causes the circuit to work at an elevated ambient temperature is also easy to cause the oxidation of the dynamic contacts of R2.
In order to prevent the occurrence of this failure, the following two methods of modifying the circuit are proposed.
(1) Fixed resistor instead of adjustable resistor R2: Firstly, adjust R2 so that the temperature of the soldering iron reaches the optimal temperature point for normal use, and then measure the value of R2 and replace it with a fixed resistor.
2) Modify the rectifier circuit: the circuit structure is shown in Fig.
Replace R1 with C (C ≈ 0.12 μF) and connect a diode D1 in parallel.
