Matt circuit

Whenever AC mains supply fails, this circuit alerts you by sounding an alarm. It also provides a backup light to help you find your way to the torch or the generator key in the dark. The circuit is powered directly by a 9V PP3/6F22 compact battery. Pressing of switch S1 provides the 9V power supply to the circuit. A red LED (LED2), in conjunction with zener diode ZD1 (6V), is used to indicate the battery power level. Resistor R9 limits the operating current (and hence the brightness) of LED2. When the battery voltage is 9V, LED2 glows with full intensity. As the battery voltage goes below 8V, the intensity of LED2 decreases and it glows very dimly. LED2 goes off when the battery voltage goes below 7.5V. Initially, in standby state, both the LEDs are off and the buzzer does not sound. The 230V AC mains is directly fed to mains-voltage detection optocoupler IC MCT2E (IC1) via resistors R1, R2 and R3, bridge rectifier BR1 and capacitor C1. Illumination of the LED inside optocoupler IC1 ac...

This is a Mains Supply Failure Alarm Circuit Diagram. Whenever AC mains supply fails, this circuit alerts you by sounding an alarm. It also provides a backup light to help you find your way to the torch or the generator key in the dark. The circuit is powered directly by a 9V PP3/6F22 compact battery. Pressing of switch S1 provides the 9V power supply to the circuit. A red LED (LED2), in conjunction with zener diode ZD1 (6V), is used to indicate the battery power level. Resistor R9 limits the operating current (and hence the brightness) of LED2. When the battery voltage is 9V, LED2 glows with full intensity. As the battery voltage goes below 8V, the intensity of LED2 decreases and it glows very dimly. LED2 goes off when the battery voltage goes below 7.5V. Initially, in standby state, both the LEDs are off and the buzzer does not sound. The 230V AC mains is directly fed to mains-voltage detection optocoupler IC MCT2E (IC1) via resistors R1, R2 and R3, bridge rectifier BR1 and capacitor...

Here is a brake failure indicator circuit that constantly monitors the condition of the brake and gives an audio-visual indication. When the brake is applied, the green LED blinks and the piezobuzzer beeps for around one second if the brake system is intact. If the brake fails, the red LED glows and the buzzer stops beeping. The circuit will work only in vehicles with negative grounding. It also gives an indication of brake switch failure. In hydraulic brake systems of vehicles, a brake switch is mounted on the brake cylinder to operate the rear brake lamps. Brake Failure Indicator Circuit Diagram: The brake switch is fluidoperated and doesn’t function if the fluid pressure drops due to leakage. The fluid leakage cannot be detected easily unless there is a severe pressure drop in the brake pedal. This circuit senses the chance of a brake failure by monitoring the brake switch and reminds you of the condition of the brake every time the brake is applied. The circuit uses an op-amp IC C...

Mains/Fuse Failure Indicator Circuit Diagram. The indicator shows when the mains is present at its output by a continuous glow of a neon bulb, La1, and when the fuse is blown by flashing of the neon bulb. When the fuse is intact, capacitor C2 acts as the series resistance for the neon bulb, so that this glows continuously. When the fuse has blow, the mains voltage across diode D1 is applied as a pulsating direct voltage to network R1-C1. Capacitor C1 charges slowly and when the voltage across it reaches 80–100 V, the neon bulb comes on. Capacitor C1 is then discharged slowly via diode D2 and the bulb. Mains/Fuse Failure Indicator Circuit Diagram When the voltage across it has dropped sufficiently, the bulb goes out, whereupon C1 slowly charges again. This process repeats itself, so that, provided the values of R1 and C1 are right, the bulb flashes visibly. The potential across capacitor C2 is a ramp with a peak value of 30 V (which is, of course, applied to the load). Note that the neo...