Showing posts with the label circuits


LAPTOP PROTECTOR CIRCUIT Protect your valuable laptop against theft using this miniature alarm generator. Fixed inside the laptop case, it will sound a loud alarm when someone tries to take the laptop. This highly sensitive circuit uses a homemade tilt switch to activate the alarm through tilting of the laptop case. The circuit uses readily available components and can be assembled on a small piece of Vero board or a general- purpose PCB. It is powered by a 12V miniature battery used in remote control devices. IC TLO71 (IC1) is used as a voltage comparator with a potential divider comprising R2 and R3 providing half supply voltage at the non-inverting input (pin 3) of IC1. The inverting input receives a higher volt-age through a water-activated tilt switch only when the probes in the tilt switch make contact with water.When the tilt switch is kept in the horizontal position, the inverting input of IC1 gets a higher voltage than its noninverting input and the output remains low. IC CD4