Here, we present a basic circuit that can power two motors for a microbot, allowing it to move around obstacles. Two light-dependent resistors (LDRs) are used to see what's in the way, and the motors are then driven in the right way to automatically avoid the obstacles. With two H-bridge motor circuits, each motor can be driven forward, backward, or stopped on its own. Circuit and how it works Figure shows the circuit for controlling two motors at once. The circuit is made up of a four-channel multiplexer (IC1), two light-sensitive resistors (LDR1 and LDR2), four BC547 npn transistors (T1 through T4), four BC338 transistors (T7, T8, T11, and T12), four BC327 pnp transistors (T5, T6, T9, and T10), and a few other parts. As was already said, the two motors are driven by two H-bridge circuits. The left side is driven by motor M1, and the right side is driven by motor

M2. As shown in Figure, each H-bridge circuit is made up of a pair of npn and pnp transistors. Between the collector and the emitter of each driving transistor is a diode that protects against the motor's back EMF spikes when the transistor is "off." The output of IC1 drives the motor-control transistors (T1 through T4) through the diodes (D1 through D6). The light-sensitive resistors LDR1 and LDR2, which are attached to the front of the robot, control IC1. On the left side is LDR1, and on the right side is LDR2. When light hits both sensors, their resistances drop, which pulls the A0 and A1 inputs of IC1 towards 0V. In this case, IC1 connects output ZA to Y0A and output ZB to Y0B, letting current flow through diodes D1 and D3. This turns on both transistors T1 and T2, which makes both motors move forward. This is when neither of the sensors picks up anything and the robot can move forward without stopping. When both sensors see an obstacle, the resistances of both LDRs go up, which pulls the A0 and A1 inputs of IC1 up. In this case, output ZA is connected to Y3A and output ZB is connected to Y3B. This lets current flow through diodes D5 and D6. This turns on transistors T3 and T4, which turn both motors in the opposite direction and move the robot away from the obstacle in front of it. If something blocks a lot of light from getting to LDR1 on the left side of the robot, the A0 input of IC1 goes high. ZA is linked to Y1A, and ZB is linked to Y1B. Since T1 is still on, the motor M1 keeps moving forward. But when the flow of electricity stops through D1, T2 turns off and motor M2 stops. So, the robot turns to the right and moves away from the obstacle. In the same way, if the robot sees an obstacle on the right, it will turn to the left. How the circuit works is easy to understand. The robot can move forward without stopping as long as it doesn't sense

anything in its way. It moves away from any obstacle and uses the information from the LDR sensors to find its way.