Two car garages have a common gate which needs to open automatically when a car enters either of the garages or cars enter both. Devise a circuit that resembles this situation using diodes for this situation.

Question

Philoid · Accepted Answer

Let us make the truth table taking garages as input and the gate as output.

So, the truth table is of OR gate.

The circuit in the diagram represents the whole system. When a car is at garage1 then D1 is forward bias and D2 is in reverse bias and vice versa. Hence the output is +V_cc. When there are cars in the both garages then both the diodes are in forward bias and output is +V_cc.