Most of the times, measurement in electronic circuits, our requirement is measuring DC voltage.  Normally, we will set the multi-meter to DC voltage mode and check the voltage levels at various points on the PCB.  Mostly, our requirement lies between 5V to 15V DC.  The circuit shown is simple, occupies less space and can directly connect to the DC voltage for measurement.  To minimize the size and power consumption, 8 pin MCU and 0.96” OLED is used in the circuit.

Universal Asynchronous Receiver/Transmitter (UART) is the most common point to point (peer) serial communication interface used in microcontrollers. It is a simple two-wire interface that requires no clock signal or any master device for serial transmission of data between two embedded devices. It can transmit data packets of variable length (5 to 9 bits) with the provision of a parity bit for error detection. That is why almost all microcontrollers have USART or at least UART peripheral built-in.  

Vehicle is part of our busy life but if we are in office or in house then we need to park vehicle outside or in parking lot. There is prone to theft or hit by other vehicle. The situation of vehicle can’t be track without visiting parking place. So this project is built to track status of vehicle, when somebody try to steal the vehicle or get hit by any others vehicle.

The project built on two boards one is for transmission which named as PARKING VEHICLE MONITOR-TX and other is for receiving which named as PARKING VEHICLE MONITOR-RX. The TX board is used to transmit the status of vehicle and other RX board is used to receive the status of vehicle and display the status on 16×2 LCD display.

While measuring voltage and current with multi-meter, the probes have to be changed its position carefully. There is a probability of damaging the multi-meter, if voltage is measured in high current mode by mistake.  In case, both voltage and current to be measured at a time, we have to use two multi-meters and care should be taken while wiring both the multi-meters. VAT meter is combination of Voltmeter, Ammeter and Thermometer. It can measure voltage and current simultaneously along with the temperature. 

The simple circuit presented here will be automatically switch ON the light / fan on entry into the room and switch OFF the load with preset delay on leaving the room. This will reduce unnecessary power consumption. This circuit is useful in drawing room, study room, dinning hall, TV room, work place, cubicle, visitors room, washroom lighting, exhaust fan, corridor lighting, staircase lighting, lift etc. Using LED2, where much lighting is not required, saves more power than using the relay RL1. PIR ( Pyroelectric / Passive Infra Red ) sensor, which outputs signal on detection of presence of humans by their motion, i.e., change in IR radiation emitted by the body.