Programmable digital timer switch using a PIC Microcontroller

Digital timer switches are used to control the operation of electrical devices based on a programmed schedule. This project describes a programmable digital timer based on the PIC16F628A microcontroller that can be programmed to schedule the on and off operation of an electrical appliance. The appliance is controlled through a relay switch. This timer switch allows you to set both on and off time. That mean ...

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Heart rate measurement from fingertip

Heart rate measurement indicates the soundness of the human cardiovascular system. This project demonstrates a technique to measure the heart rate by sensing the variation of the blood volume inside a finger artery, which is caused by the pumping action of the heart. It consists of an infrared LED that transmits an IR signal through the fingertip of the subject.  A part of this infrared light is reflected b ...

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Experimenter’s board for enhanced mid-range PIC microcontrollers (PIC16F1827 and PIC16F1847)

The PIC16F628A has always been my first choice for microcontroller-based projects. It is simple, inexpensive, and easily available. Due to its compact size (18 pins) it occupies lesser space on the circuit board, and meanwhile, it is powerful enough to serve most of a hobbyist’s needs. It is a very well accepted successor of the classic PIC16x84, and therefore, the tons of resources available for PIC16x84 o ...

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00 to 99 minute timer using PIC16F628A microcontroller

Last week I was browsing my old backup hard drive and I found a source code for a very simple PIC based digital timer that I made a couple of years ago. The actual hardware of the project isn’t with me anymore. I might have lost it when I moved from my old apartment into my new home. However, I thought this might be a good practice project for beginners and so I am sharing it here. I am not going to build i ...

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Making a digital capacitance meter using microcontroller

Capacitors are one of the most common passive electrical components that are extensively used in all kinds of electronic circuits. In this project, we will discuss a technique of building a digital capacitance meter using a PIC microcontroller. This project can measure capacitance values from 1 nF to 99 ?F, with a resolution of 1 nF. The technique is based on measuring the time elapsed when a capacitor is c ...

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2-Wire Keypad Interface Using a 555 Timer using PIC16F628A

Keypads are a very commonly used input device in microcontroller-based systems. In a keypad, multiple switches are arranged in rows and columns so that they could be interfaced to a microcontroller with a minimum number of I/O pins. For example, a 12-key keypad is arranged in a 4×3 format, which allows to interface the 12 keys to a microcontroller with only 7 connections. The location of each key on the key ...

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100MHz frequency counter with PIC16F628A – LCD Display

This project shows how to build a very simple yet very useful tool that every DIY enthusiast should have in his lab: a 100MHz+ frequency counter. The schematic is fairly simple and straightforward and uses a PIC16F628A microcontroller for measuring frequency and a high speed comparator for signal amplification and conditioning. The microcontroller uses its internal 4MHz oscillator for the CPU clock. Timer1 ...

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100MHz frequency counter with PIC16F628A – LED Display

Couple of weeks ago I purchased from eBay one of these amazingly cheap an useful modules with MAX7219 LED driver and 8 digit LED display. It is ideal for frequency counter project. The problem was the absence of library for PIC microcontrolers. Luckily, I found a great library for Arduino and I reworked it to be compatible with PIC. The schematic of the frequency counter is actually almost the same as the p ...

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Single button code entry for a digital lock using PIC16F628A

The Button Code is a system that allows a single button to act as a keypad. The user enters a 4 digit code into the system using button taps. The button can be placed where the public can access it since like a keypad there are many combinations to keep guessers from activation the system. When the correct code is entered a form-C relay is activated (Normally Open and Normally Closed relay contacts). When a ...

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Breadboard module for PIC16F628A

Here’s another breadboard module that carries a PIC16F628A microcontroller. The power supply pins and the I/O ports of the PIC16F628A microcontroller are accessed through male headers. It can be easily plugged into a breadboard and is very useful for quick prototyping. It frees up a lot of space on the breadboard since the oscillator, reset, and ICSP circuits are already built on the module. It is different ...

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