Homemade soldering iron power supply

About what to work with low voltage electric soldering iron and safe and convenient, everyone knows. In production and in educational laboratories, low-voltage small-sized soldering irons have long been universally used, but in everyday life we ​​most often have to be content with dangerous and bulky tools that operate on 220 V mains. make low voltage soldering iron power supply it’s not difficult for yourself.

The power supply is the simplest capacitive AC load limiter.

In the first, desktop version, the device is made in a light metal case, has two switches and one control indicator of the mains voltage, signaling about three switching modes.

Combinations of two toggle switches SA1 and SA2 (Fig. 1) set four operating modes of the device: both in the lower position according to the scheme - off, SA1 above, SA2 below - low 32 V, SA1 below, SA2 above - normal 36 V, both switches at the top - reinforced glow of 39.5 V. An electric soldering iron is connected to the device through a connector.

Author schemes deliberately did not provide for the design of the block of devices for solder and flux, since these sets usually take up relatively much space. Therefore, the unit has only a curly stand for a soldering iron, which, when carried, can be removed inside and does not protrude beyond the dimensions of the unit.

Under the transparent cover that covers the case window, an indicator is located between the switches. The bottom of the body is fixed on a loop, the axis of which is made of copper wire diameter 3 mm curly soldering iron stand.

The power supply weighs 375 g, and its dimensions (without a soldering iron) are 110X55X55 mm.

In the second version, the power supply is designed to operate on a mains voltage of 127 V or 220 V. In the working state of the unit, two halves of a light metal box connected on hinges are disclosed. One contains elements of an electronic device (Fig. 2), controlled by three switches mounted on the top panel of fiberglass. The indicator is viewed through a figured window, located in a row with the switches S.

The other half is empty, serves as a stand for the soldering iron during operation. The power cord of the soldering iron is connected to the unit inextricably.

Assembled, the soldering iron with the cord is placed in the left half of the box, then it is folded and fixed with a lock. The weight of the kit is about 600 g, the dimensions in a folded form are 170X60X50 mm.

The device uses metal-paper capacitors, for example, MBGO or MBM for a voltage of at least 250 V, toggle switches - TP1, the limiter resistor in the indicator circuit can be any type of resistance from 50 to 100 kOhm.

A power supply unit designed for the PNT-20 type electric soldering iron is quite suitable for any other similar mounting tool, adjusted for its nameplate data (resistance and current).

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