Thermostatic soldering iron circuit

Constant temperature soldering iron is generally 45W. It is powered on and off intermittently, and the actual power consumption is 25W. It uses a 24V transformer for power supply, both AC and DC.
The constant temperature soldering iron has the advantages of energy saving, high efficiency, low consumption and long life. It is an ideal soldering tool in the electronic product production and electronic repair industry. Figure
7-41a shows the appearance of two constant temperature electric soldering irons, and Figure 7-41b shows the circuit diagram of the constant temperature electric soldering iron . ．
    Generally speaking, the power and type of the soldering iron should be reasonably selected according to the welding object. If the parts to be welded are larger, the power of the soldering iron used should also be larger
. If the power is small, the welding temperature is too low, the solder melts slowly, the flux is not easy to volatilize, and the solder joints are not smooth and firm. This will inevitably cause
the appearance quality and welding strength to be unqualified, or even the solder cannot melt and the welding cannot be performed. However, the power of the soldering iron should not be too high. If it is too high,
too much heat will be transferred to the workpiece to be welded, causing the component solder joints to overheat, which may cause damage to the components , causing the copper foil of the printed circuit
board to fall off, and the solder joints to be soldered. The material flows too fast on the welding surface and cannot be controlled.