Hello friends, I hope you are doing well. In the previous tutorials, we studied the basics of inverter topologies and the major components of an inverter . We will now connect those ideas and study how an AVR controller can create a sine reference for a pulse-width-modulated inverter. This tutorial explains the signal chain, frequency calculations, H-bridge states, LC filter and transformer. The AVR code is an educational SPWM reference generator for an ATmega16 running at 8 MHz. It is useful for simulation and low-energy waveform testing, but it must not be connected directly to power MOSFET gates. A physical inverter needs proper high-side and low-side gate drivers, hardware dead time, current limiting, voltage feedback, thermal protection and a safe PCB layout. The original project pack ...
Hello friends, I hope you are doing well. In the previous tutorial, we studied the working principle of a relay . Today, we will connect a 12 V relay to a PIC18F4550 microcontroller through a ULN2003A driver. A relay coil needs more voltage and current than a microcontroller pin should provide. It is also an inductive load, so it produces a voltage transient when switched off. The ULN2003A solves these interface problems by providing seven low-side Darlington drivers and seven internal clamp diodes in one package. The key point is that the ULN2003A does not convert a 5 V logic signal into a 12 V output. The 12 V energy comes from a separate 12 V supply. A logic high merely turns on one internal driver, which connects the low side of the relay coil to ground. We will examine that current pa ...
Hello everyone! I hope you are doing well. In this tutorial, we will study the relay from its basic construction to practical selection and control. A relay allows one electrical circuit to operate contacts in another circuit. This makes it useful when a low-power controller must switch a different voltage, a larger load or an electrically isolated circuit. We will focus first on the common electromechanical relay because its moving contacts make the operating principle easy to understand. We will then compare electromagnetic, reed, solid-state, thermal and hybrid relays, calculate coil current, discuss contact ratings and examine a safe microcontroller driver. A relay is often described as an automatic switch, but that short definition hides several important details. The coil and contact ...
Hello friends! In this tutorial, we will design an LED blinking project using the PIC16F877A microcontroller. It is a simple project, but it introduces several ideas that appear in almost every embedded system: configuring an I/O port, choosing an oscillator, building a reset circuit, calculating LED resistors, generating a time delay, compiling a program, and loading the resulting HEX file into Proteus. We will connect eight LEDs to PORTB and switch the complete port between logic low and logic high. Once this basic version works, you can change the output patterns and timing to create a running light, binary counter, or status display. The important objective is to understand why every connection and every program statement is present. Figure: The original simulation shows the PORTB LED ...
