This is the cell phone shield circuit which can be used as mobile charger. Give protection to your cell phone from unexpected use or theft working with this easy circuit. It is able to produce a loud chirping sound when someone tries to take away the mobile handset. The added function is that the circuit also operates as being a mobile charger. The circuit is powered by a step-down transformer [...]
This is the shutter guard circuit which has sensitive vibration sensor, piezo-sensor. This circuit is specifically designed for outlets to defend towards theft. It can recognize any mechanical or acoustic vibration in its area when somebody attempts to break the shutter and instantly turn on a lamp and sound an alert alarm. A 15-minute time delay right after switch-on makes it possible for adequate time for the outlet or shop [...]
This is the circuit diagram of white line follower toy. The actuator of the toy is the DC motor. This circuit can be used for a toy car to follow a white line, this circuit also known as very simple robot: “line follower without microcontroller”. The motor is either a 3v type with gearing to steer the car or a rotary actuator or a servo motor.