The EKI 2006 Burglar Alarm Kit uses a simple SCRs trigger circuit to sound an ear piercing alarm whenever a trigger switch is interrupted.

Use either normally-open or normally-closed switches. Includes instructions on how to mount as a car alarm. Operates on 9-12V. Principles taught: SCR, control systems. Components: 2 resistors, 2 capacitors, 2 diodes, SCR, buzzer, slide switch, battery snap.