“Superheater” for a soldering iron

Greetings, homemade radio amateurs!

On the Internet, there are many schemes of various power regulators that allow you to reduce the power of the soldering iron to the desired level, these schemes are simple, compact, cheap and therefore popular. At the same time, on the contrary, increasing the power of the soldering iron is not an easy task, this will require a whole high-voltage voltage converter – it will be the size of a whole station. In addition, with an increase in the supply voltage, and, accordingly, the power, the service life of the heater decreases. Despite this, an increase in power by 10-20% will not damage the spiral, and such an increase can be carried out by a very simple method, as the author of the described article was convinced of.
An increase in the power of the heater can be achieved by rectifying the alternating mains voltage and then smoothing it on the capacitor. Many people remember from school physics that the effective (operating) voltage in the network is 220V, but the amplitude is about one and a half times greater and is 310V. In order to “extract” all 310V from the AC voltage and force them to heat up, the voltage must be rectified and smoothed. It will work as follows:
The input voltage is a normal sine wave. After leaving the diode bridge, the lower half-periods of the sinusoid seemed to be inverted and acquired positive polarity. This is shown in the upper right picture. In this case, the red line shows the effective voltage value of 220V. If you add a capacitor now, then at the moment of the voltage peak it will accumulate charge, and at the moment of the voltage “dip” – on the contrary, give the accumulated charge to the load (heater). The blue lines show the voltage oscillogram with the capacitor – it would be an ideal straight line with a voltage of 310V if the load were not connected. Thus, the diode bridge with a capacitor allows you to increase the effective voltage across the load, and the connected fingertip will heat up a little more. However, a miracle will not happen and the efficiency will not increase from this – the consumption from the mains will increase together with an increase in the voltage across the load.
The electrical schematic diagram of a diode bridge with a capacitor will look like this.
You can use any diodes rated for at least 600V and 1A, or use a diode assembly with the same characteristics. The capacitor must be rated for a voltage of at least 400V. To ensure an increase in load power, its capacity should be about 4.7 – 10 μF, the larger the capacity, the stronger the increase in power will be. However, you should not get too carried away with increasing the capacity – the capacitor will become large in size, besides, the stock of heaters in terms of power is not rubber.
The circuit can be slightly modified by adding a switch that allows you to switch between capacitors of different capacities, respectively, to increase the heating temperature of the soldering iron more or less. A NTC thermistor is added at the input in front of the diode bridge, which will reduce the inrush current caused by the charging of the capacitors and protect the diode bridge.
When using such a “superheater”, of course, there is a certain risk of burning the heater of the soldering iron. However, this would mean that the heater itself was designed without a power reserve and would not last long on its own. Usually, all electrical appliances are designed for a mains voltage of 240V, although in reality the voltage in the mains is often lower than 220V rather than higher. For this reason, many heating electrical appliances, including soldering irons, do not give up all the power declared by the manufacturer for heating.
It is possible to mount a diode bridge with a capacitor even inside the socket. It is important to remember that this socket is “special” exclusively for a soldering iron. Turning on other electrical appliances according to this scheme can lead to their failure. Happy build!


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