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         The IC555 is a widely used IC. It has two modes of operation. Namely, Astable and monostable mode. In the Monostable mode, a negative clock pulse to the trigger pin (pin 2) will generate a output for the duration depending on the chosen values of the resistors and the capacitor. In the Astable mode of operation, The IC555 generates square waves with a duty cycle and frequency depending on the chosen values of the resistors and capacitor. for the values I chose, I got a pulse for approximately 1 second. with a 66% duty cycle.          In the schematic, the jumper 1 (JP1) represents the output for which I had connected a LED. and jumper 2(JP2) represents the header pin for input supply. Schematic PCB design

          This circuit will turn on a device preferably a light bulb for a fixed duration of time when it detects movements. this circuit is connected in parallel with a pre-existing switch for the device.Taking example for a light bulb, when a person walks into a room, the device turns ON for a fixed duration of time. If the person wishes to stay in the room for a longer duration, he can turn on the switch manually, since it is a parallel wiring.          This circuit can be used in various applications like staircase lighting or for a room. when someone passes the light turns ON and automatically turns OFF, there by saving a lot of energy.          The heart of the circuit is the PIR module, which sends out a +ve pulse when it detects a movement. PIR stands for Passive Infrared Receiver, implies it does not have a source of IR radiation. some modules have an option for both +ve or a -ve pulse when the motion is detected. the module I secured had the option only for a positive

            Couple of days ago, I was at the gym. I was doing push-ups and I lost my count. So I wondered whether I can make a device to count the number of push-ups I do. couple of days later, I had totally forgot about this idea, until recently I saw a project my friend had made at his office. It was a 7-Segment clock. So I got motivation to start my push-ups counter.          The push-ups counter consists of 3 main blocks. Namely,  IR proximity detection block BCD counter BCD to seven segment encoder Push-ups counter          First IC from the left is the quad op-amp LM324, the second is the BCD counter CD4510 and the 3rd is the BCD to seven segment encoder CD4511 I constructed the IR proximity detection by connecting an IR receiver to the non-inverting terminal of LM324 (I prefer LM358. I did not use it because I had none at home) and connecting a 10k potentiometer to the inverting terminal. varying the potentiometer will change the sensitivity of the IR proximity d