This circuit  Logic Probe it  indicates the logic state of the node of any TTL logic circuit. To do that, we have to supply the probe with the same power of the circuit that we want to analyse: same Vcc and same GND. To check the logic level, we must connect the “Test” wire of [...]

This circuit uses a PIC16F685 and an OPA4342 (or LM324) to randomly generate pleasant audio tones. The interesting part about this project is that it’s not calculating the frequencies required to make the tones, it’s counting the time intervals. Source: Poweredbynerd

The lamp is controlled by a PIC microchip 16F628 controller and I decided to add a Sony IR remote control receiver to the design, which my brother was very kind to code in a PIC microchip 12F683 controller. I must say I am very pleased with the finished result. The 3 Watt LED module is [...]

This timer, which allows a time delay between 100 milliseconds and 56 hours, in reality, the timer is as follows also based on counting pulses from an oscillator, the difference lies partly in the fact that we do not see the oscillator as it is integrated into the CIP, and secondly that the duration the [...]

This circuit is based on a PIC 16F628A clocked at 4 MHz, the code is totally different from that used in my frequency counter 004 and the timebase is here fixed at 100 ms for the range of measure, s extends from 100 Hz to 20 MHz. Source: sonelec-musique

The total cost of the project is about $15. Source: Rototron

Led Voltmeter The heart of the circuit is the LM3914N dot-bar volt meter IC, U2. This chip is operated in the expanded-scale mode.

In this project  i will show you how to build a quite fancy 8 by 10 L.E.D matrix(with scrolling text and animations) using the Arduino and 4017 decade counter. This type of matrix is easy to make and program and it is a good way learn how to multiplex. Source: Syst3mX

This project uses a Microchip PIC microcontroller and an Infra-Red LED to act as a PC controlled cable TV changer. A very simple program on the computer sends the channel number over RS232 to this PIC based IR transmitter which creates the correct waveform for the digits to be sent. Source: Andrew M. Bishop

Source: escol

Lithium-Ion cells require a constant voltage, current limited charge. The voltage must be accurately limited to 4.2V, as higher voltage reduces cell life. This circuit is designed to meet these requirements using standard components. Source: bhabbott