When teamed up with an oscilloscope, this simple circuit provides a means of measuring capacitor ESR. A 555 timer (IC1) configured as a 2.3kHz free-running oscillator acts as the timebase. It provides narrow (7.7µs) pulses to the capacitor under test via a NAND Schmitt trigger (IC2) and transistor Q1. A 100Ω resistor in series with Q1 limits current flow to about 50mA. Therefore, an ESR of 1Ω will produce pulses across the test capacitor of 50mV, which means that an oscilloscope with a vertical sensitivity of 5mV can measure ESR down to 0.1Ω or less.
Oscilloscope ESR Tester - [Link]
A typical capacitor checker measures the capacity (usually in micro farads) of the test capacitor. Some advanced units also test for leakage current. Most of these testers require that the capacitor be removed from the circuit. Unless the capacitor has totally failed, they will not detect a high ESR value. In a typical circuit, there may be 10’s or 100’s of capacitors. Having to remove each one for testing is very tedious and there is a great risk of damaging circuit boards. This tester uses a low voltage ( 250mv ) high frequency (150khz) A/C current to read the ESR of a capacitor in the circuit.
Capacitor ESR Meter – [Link]
The AVR family of microcontrollers use a modified Harvard Architecture which uses 3 types of memory, most of which are on chip. Learn more about the memory types on the link below.
AVR Memory Architecture – [Link]
EEPROM (Electrically Erasable Programmable Read Only Memory) Is non-volatile memory, meaning it persists after power is removed. The ATmega168 microcontroller has 512 bytes of EEPROM which can be used to store system parameters and small amounts of data. This tutorial shows you how to read and write EEPROM.
Reading and writing Atmega168 EEPROM – [Link]
This project will show how to breadboard a simple USB generic HID device, creating the PIC18F firmware and finally creating the Windows interface for the device which will allow you to control a LED from the PC and read the state of a push-button from the device. Check it on the link below.
Building a PIC18F USB device – [Link]
This project is a nixie tube reverse geocache box which unlocks to reveal its contents only when it’s in a certain place on the globe. It uses an Arduino, a GPS sensor, and three nixie tubes, which indicate the box’s distance from that special spot. When the button is pressed in that spot, a servo motor unlatches the lid. [via]
Nixie tube reverse geocache box – [Link]
This project is a mounting system that adds mechanical tilt control to the iPhone. The unit uses two servo motors to move the iphone on the X and Y axis. The system is controlled by an analog joystick and an Arduino board. It can be used to play accelerometer-based games on the iphone. [via]
iPhone tilt motion controller - [Link]
Simon Inns builds this realtime PIC based audio spectrum analyzer. The analyzer uses Fast Fourier Transform routine written in C to run as efficient as possible on the 8 bit PIC18F4550 mcu. The output from the FFT is displayed using a 128×64 graphical LCD to allow a real-time view of an audio signal. [via]
PIC spectrum analyzer uses Fast Fourier Transform routine – [Link]