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]
This project is a LED array PWM dimmer using 555 timer IC. The 555 timer IC is configured as a PWM generator. A potentiometer controls the charge and discharge times and thus the duty cycle of the PWM. As PWM duty cycle is varying the brightness of the led changes. Check schematic on the link below.
An LED Array PWM Dimmer with the 555 - [Link]
This project is an IR beam break detector that has a range of 10m. After publishing IR Short Distance Beam Cut Detector Giorgos Lazaridis received requests for a version that will have extended range so he build the circuit on the link below. The transmitter is based on 556 timer IC that has two 555 timers inside and an high power IR led. The receiver is based on TSOP1838 IR receiver chip, a 555 timer IC and a 4017 decade counter. Check schematics and construction details on the link below.
Long Range (10m) IR Beam Break Detector – [Link]
This project is a time lapse intervalometer based on 555 timer IC. It can be used with SLR cameras to take time lapse photographs. Schematic is designed on ExpressPCB. Here is how the circuit works:
When you turn it on, the camera will get a false signal and take a picture. Then the big capacitor will slowly fill with charge while the green LED is on. How slowly is chosen by the variable resistor. When the cap discharges, the 555 outputs a signal to the transistor which connects the shutter control to ground. The red LED lights up and the camera takes a picture.
Time Lapse Intervalometer for SLRs with 555 timer IC - [Link]
This article discuss about the 555 timer IC. It talks about the history of it, the modes of operation (Monostable, Astable and Bistable), the pinout etc. It also introduces a LED blinker circuit to show it in operation.
555 Timer IC - [Link]
This circuit shows a simple touch switch using 555 timer switch and a relay. You touch the on plate to energize the relay.
Touch Switch ON-OFF – [Link]
This tutorial shows how to use the Timer1 module inside PIC12F683 as an asynchronous counter to compute the frequency of an external clock source. The external clock is connected to the GP5/T1CKI port of PIC12F683 and the measured frequency value is sent to a PC through serial port to display on an hyperterminal window. A 555 Timer IC operating as an astable multivibrator is used as the external clock source. The Timer1 module is 16-bit so it can count up to 65535. If the Timer1 is turned ON for 1 sec, the maximum frequency it can measure is 65535 Hz. Any frequency higher than this will create Timer1 overflow. An interrupt service routine is also written to demonstrate how to detect the overflow and take appropriate action. This concept can be extended to measure higher range frequencies.
How to measure frequency of an external clock source using PIC - [Link]
The 555 Astable generates a clock for this circuit, an oscillator giving a square wave output at pin 3 which is counted by 4017 to give a running lights effect.
The decade counter-divider CD4017 has 10 outputs, for every low to high transition at the clock input, rising edge, the counter advances one LED. After going one full circle the the first LED lights again and it goes on. You can vary the value of R2 100K Linear potentiometer to make LEDs run fast or slow.
Running Lights with CD4017 - [Link]
This project is a 555 timer based PWM controller features almost 0..100% pulse width regulation while keeping the oscillator frequency relatively stable. The frequency range from about 170 to 200 Hz. Check schematic on the link below.
Simple PWM controller - [Link]
user drj113 on Instructables writes:
This Instructable will show you how to make your own original stylophone – The schematic that this is based on is my own, so it is free from Intellectual property restrictions. It is based around a 555 timer (so it could be an extension of the recent “Know Your 555 timer” article), and uses an ubiquitous LM386 audio amp so it can have enough volume to stand out from the crowd. [via]
DIY Good old fashioned stylophone – [Link]