Flashlight control model motor circuit diagram

When there is no light, the photovoltaic cells PC1 and PC2 show high resistance, Q1 and Q2 are turned on, the contact of the relay K1 is disconnected, the contact of the relay K2 is connected, and the partial voltage of the battery B3 on the Rs potentiometer is connected in series with B1 and B2 through the relay K3 Added to both ends of the motor , due to the opposite polarity, adjusting R3 can cause no current to flow in the series circuit. If K3 does not move and the contacts are blocked, the motor will not rotate.

When the flashlight shines on PC1, PC1 shows low resistance, which is similar to short-circuiting the b and e poles of Q1. Q1 is cut off and the contact of K1 is connected, so that the B1 and B2 batteries are connected in series to both ends of the motor, and the motor rotates. And because the K1 contact is connected, the two ends of K3 are directly connected to the center tap of R3 and the positive terminal of the B3 battery. Therefore, K3 is turned on and the contact of K3 is connected. Even if the light of the flashlight is removed, the contact of K3 can still maintain the rotation of the motor. . Only when the flashlight shines on the photocell PC2, Q2 is cut off, the contact of K2 is disconnected, the path of K3 is cut off, and the contact of K3 is disconnected, the motor stops rotating.