Alarm with Emergency Light 220V

This project simulates a compact Alarm with Emergency Light circuit that operates on a 220V supply and automatically activates both sound and light during a power failure or emergency condition.

The circuit is built around a combination of NPN and PNP transistors to control the alarm and lighting stages.

Q1, Q3, Q4 (BC547) serve as signal amplifiers and control drivers, handling switching and triggering functions.
Q2, Q5 (BC327) are used as power drivers to supply current to the lamp and speaker stages, ensuring efficient output under low-voltage battery operation.

The circuit uses:

• SW1, SW2 (SPST switches) for power and mode control.
• SW3 (SPDT switch) to select between alarm or light mode manually.
• LP1 - a 2.2V–2.5V torch lamp rated at 250–300 mA — provides illumination during power outages.
• SPKR - an 8 Ω loudspeaker — produces the alarm tone generated by the transistor oscillator network.
• B1 — a 2.5V rechargeable battery (two Ni-Cd AA cells in series) — acts as the backup power source.

When mains power fails, the battery automatically powers the circuit, activating the emergency lamp and audible alarm simultaneously. This makes the system ideal for safety indication, emergency signaling, or small-scale home alarm demonstrations.

Components