The relay is energized by entering the first four digits of your chosen five-digit security code. Entering the full five-digit security code - will De-energize the relay. When "A, B, C & D" are pressed in the right order - and within the time set by C1 and R2 - current through R11 switches Q6 on. This energizes the relay. When "A, B, C, D, & E" are pressed in the right order - and within the time set by C1 and R2 - current through R7 switches Q5 on. This de-energizes the relay. The circuit was designed to control the Modular Burglar Alarm System - but it will have other applications. A simpler - A Four-Digit Version - of the circuit is also available.
Here is the circuit diagram of an infrared motion detector that can be used to sense intrusions.Infra red rays reflected from a static object will be in one phase, and the rays reflected from a moving object will be in another phase.The circuit uses this principle to sense the motion.The IC1 (NE 555) is wired as an astable multivibrator.
The IR diode connected at the output of this IC produces infrared beams of frequency 5Khz.These beams are picked by the photo transistor Q1 .At normal condition ie; when there is no intrusion the output pin (7) of IC2 will be low.When there is an intrusion the phase of the reflected waveforms has a difference in phase and this phase difference will be picked by the IC2.Now the pin 7 of the IC 2 goes high to indicate the intrusion.An LED or a buzzer can be connected at the output of the IC to indicate the intrusion.
Comparators IC2a and IC2b are belonging to the same IC2 (LM1458).So the power supply is shown connected only once.No problem.When there is disturbance in the air or vehicles passing nearby,the circuit may get false triggered.POT R5 can be used for sensitivity adjustment.
Here's a simple lie detector that can be built in a few minutes, but can be incredibly useful when you want to know if someone is really telling you the truth. It is not as sophisticated as the ones the professionals use, but it works. It works by measuring skin resistance, which goes down when you lie.Here are the details of the specific parts you will need
Electro-optical sensors are those which convert the light rays in to electronic signal very similar to the photo resistor, these are applied in emergency lamps such that when there is light it is made to switch off and when there is no light it automatically made to switch on. In aviation, electro-optical devices have been used as part of the avionics, in order to expand both range and vision at low ambient light levels.