On the front panel of the box, fit power switch S1 and a 3-pin socket for connecting the soldering iron. to This tutorial will guide to to make simple circuit using NPN transistor as a. Connect the battery and transformer with suitable current-carrying wires. Electronics Projects, 400W Transistor Power Amplifier Circuit audio. Chakravorthi his simple circuit works on. Assemble the circuit on a generalpurpose PCB and house in a suitable cabinet. provided for the proper gain of Ici gain ( npn ) driver transistor T1 to. This voltage can be used to heat your soldering iron. When you power the circuit using switch S1, transformer X1 produces 230V AC at its primary terminal. 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. A 230V AC primary to 12V-0-12V, 4.5A secondary transformer (T1) is used. The above circuit could supply power of about 300 watts and you can increase it by using high. A 24V center tapped transformer was used and you can substitute it with powerful transistors to deal with high current. Use suitable heat-sinks for transistors Q5 through Q8. The Transistor 2N3055 can handle 15 Amps each, you can also use high current transistors if you thought of upgrading this circuit.
The outputs from the drivers are fed to transistors Q7 and Q8 (each 2N3055) connected for push-pull operation.