Bomb detector is normally used to hunt hidden treasures such as metal coins, iron ore, aluminium or even silver and gold buried under the earth.
The simple Bomb detector comprises two oscillators, one working at 455 KHz and the other at a slightly lower frequency of 452 KHz. One of the oscillators uses an IF transformer where as the other uses an inductor in the form of a search coil.
The two oscillators are coupled together through a capacitor of 120 pf value. A beat frequency of 3 KHz is produced if the search coil is taken near metal. The beat frequency is amplified and heard through headphones as shown in the circuit. Alternatively it can be heard through a MW Pocket receiver.
The search coil oscillator is tuned by the 2J gang condenser. Transistor T3 is used as an amplifier to make the beat frequency obtained through the two oscillators built around T1 and T2 audiable. The circuit operates on 9V DC.
Through parallel port, a PC is connected with the Electronic circuit. The Bomb detector is fixed with a robot. The computer controls the overall operation of the robot. The user can simply feed the distance using the computer where the robot is to go and search. The robot operates accordingly with the commands of the computer