SECOND PRIZE
TO BUILD ANTI-THEFT CIRCUIT USING ELECTROMAGNETIC RELAYS
Author: Doan Thi Y Nhi
Instructor: Phan Cu
Unit: Tran Hung Dao High School, A Luoi District
1. The initiative:
Derived from the reality of A Luoi district in particular and many other places in the country that thieves break into houses to steal people’s property regularly. Pressing with the situation, after studying a lesson about magnet – application of electromagnets (physics – grade 9), I have an idea of doing a simple anti-theft circuit which could be put in houses to alarm at night. Once, it can be a tool against thieves, other, I can turn theory in our books into real and understandable model which can be served in teaching courses to help students enjoy the subject.
2 Structure description of the product:
The circuit consists of: 1 electromagnetic relay, 1 small transformers (220V in; 12V and 6V out), 2 source filter capacitor, 1 electric bell, 4 Led bulbs (2.5V), 1 electric plug and a wooden house as model.
Assembling: Connect 220V source into a primary coil of the transformer and divide voltage into 2 sources: 6V and 12V then bring them to the filter capacitors and connect with two electrical circuits.
– The first circuit: Includes a relay connected with doors.
– The second circuit: Includes bell which is parallel to the lights
3. The operation principle of the product:
– When doors close, power is supplied for the 1st circuit, the closed relay makes the circuit close, while the others 2 opened, bell and light are in standby state.
– When doors open, the 1st circuit opens and the turn-off relay makes the 2nd circuit close, then the bell rings and the light is activated.
4 The novelty: Same studies have not been found in locality
5 Creativity:
It is in fact the alarm circuit, but I’ve combined with Led light since I know the psychology of crooks that they always afraid of the light.
6 Applicability of the product:
– The product has high applicability. It is suitable to the reality, easy to install and inexpensive in cost.
– The product may serve well for life, in learning and in teaching.
LE HOANG GIA UYEN
