Circuit Diagram
How to Build It
- Place the NE555 timer on the breadboard, configured as a siren oscillator (frequency modulated by a second timer or large capacitor).
- Connect the output (pin 3) to a speaker or power buzzer.
- Add a hidden switch (or a reed contact) in series with the circuit's power supply.
- Power the circuit through the switch.
- Trigger the switch — the siren should start immediately and sound continuously.
Bill of Materials
| Product | Code | Qty |
|---|---|---|
| Buzzer | LD-BZPG-2312 | 1 |
| Integrated circuit | — | 1 |
| Switch (latching/momentary/panel) | 09068PI | 1 |
| Capacitor (electrolytic/ceramic/SMD/film) | 860020674015 | 1 |
| Resistor | DR47K-8/9 | 1 |