The ETB-189 trainer is a practical and interactive model designed to demonstrate the working of a simple burglar alarm system using a 555 timer IC and an LDR (Light Dependent Resistor). This trainer introduces students to the concepts of light sensing, threshold triggering, and timed response generation using basic components.

The alarm is activated when the light falling on the LDR is interrupted (e.g., due to a person passing by), simulating a breach. The 555 timer processes the signal and triggers an audio/visual alert output.

The trainer includes:

• IC 555 based light-sensing circuit

• LDR as the detection sensor

• Inbuilt constant regulated (C.R.) power supply

• Audio/visual alarm output

• Test points for analysis and waveform observation

This model is excellent for basic electronics, security system design, and sensor application training in educational labs.