Circuit Diagram
How to Build It
- Place the BC547 transistor on the breadboard.
- Connect a bias resistor from the positive rail (9V) to the transistor's base.
- Feed the incoming audio signal through a capacitor into the base (the capacitor blocks DC, passes only the signal).
- Connect the collector to the speaker, and the speaker's other terminal to the positive rail.
- Connect the emitter to GND.
- Feed in a small audio signal (from a phone, via a jack cable) — the speaker should play it back, louder than the input.
Bill of Materials
| Product | Code | Qty |
|---|---|---|
| Speaker cable | KAB0352 | 1 |
| Capacitor (electrolytic/ceramic/SMD/film) | — | 1 |
| Resistor | DR47K-8/9 | 1 |
| Transistor (incl. IGBT) | — | 1 |