Inverter for Soldering Iron Using Transistor

Inverter for Soldering Iron

        Here is a simple but inexpensive inverter for using a small soldering iron 

(25W, 35W,etc) in the absence of mains supply. It uses eight transistors and a few resistors

and capacitors.

      Transistors T1 and T2 (each BC547) form an astable multivibrator that produces

50Hz signal. The complementary outputs from the collectors of transistors

T1 and T2 are fed to pnp Darlington driver stages formed by transistor

pairs T3-T5 and T4-T6 (utilising BC558 and BD140). The outputs from the

drivers are fed to transistors T7 and T8 (each 2N3055) connected for push-pull

operation. Use suitable heat-sinks for transistors T5 through T8.

A 230V AC primary to 12V-0-12V, 4.5A secondary transformer (X1) is

used. The centre-tapped terminal of the secondary of the transformer is

connected to the battery (12V, 7Ah), while the other two terminals of the

secondary are connected to the collectors of power transistors T7 and T8,

respectively.

      When you power the circuit using switch S1, transformer X1 produces

230V AC at its primary terminal. This voltage can be used to heat your soldering

iron.

     Assemble the circuit on a general purpose PCB and house in a suitable

cabinet. Connect the battery and transformer with suitable

current-carrying wires. On the front panel of the box, fit

power switch S1 and a 3-pin socket for connecting the soldering iron.

Note : that the ratings of the battery, transistors T7 and

T8, and transformer may vary as these all depend on the load

(soldering iron)

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