The scenario
Designing a basic electronic alarm system for home security with multiple door/window sensors and a loud siren.
What is in this drawing
Read the decisions behind it.
01
Use of discrete transistors instead of ICs for simplicity and reliability
02
Diode OR gate for combining multiple sensor signals
03
Capacitor debouncing for stable trigger
When a simple, low-cost alarm system with multiple sensor inputs is needed, and a 555 timer IC is unavailable or not preferred.
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