Hi i am ramya i would like to get details on automatic brake failure indicator pdf. now i am studing final year b-tech .

In vehicle hydraulic brake systems, a brake switch is mounted on the brake cylinder to drive the rear brake lights. The brake switch operates with fluid and will not operate if fluid pressure decreases due to leakage. Fluid leakage can not be detected easily unless there is a severe pressure drop on the brake pedal. This circuit detects the possibility of a brake failure by controlling the brake switch and reminds you of the brake status each time the brake is applied.

The circuit uses an op IC CA3140 (IC2) as voltage comparator and timer NE555 (IC3) in mono stable alarm configuration. Voltage comparator IC2 detects the voltage level through the brake switch. Its non-inverting input (pin 3) obtains half of the supply voltage through the potential dividing resistors R3 and R4 of 10 kilo-ohms each. The inverter input (pin 2) of IC2 is connected to the brake switch via diode D1, IC 7812 (IC1) and resistor R2. It receives a higher tension when the brake is applied.