Tag Archives: 555

Warning LED Flash Light


LED Flasher is a simple project producing a flashing effect of six LED’s.  This project can be used in all areas where you want to draw attention.  Hi-glow LED’s providing enough flashing light to attract your attention. Can be used as warning light.


  • Supply input 12 V @ 35 mA (6 to 15V Dc Possible)
  • Onboard preset to adjust flash rate
  • Terminal pins for connecting supply input
  • Four mounting holes of 3.2 mm each
  • PCB dimensions 53 mm x 35 mm
  • CN1: Supply in 12V DC (6V-15V Supply Possible)
  • PR1 : Flash Frequency Adjust

Warning LED Flash Light – [Link]

Disco Lights with IC555


This is a simple 555 timer IC circuit that is able to power two strings of LEDs alternative.

Disco lights are mostly used in decoration made with colourful LEDs. For begginners, this is a compact circuit using a single chip IC. IC555 is connected here to form a multivibrator. The blinking speed can be easily adjusted by varying the preset 500kΩ. You can use any colour of LED.

Disco Lights with IC555 – [Link]

Pulse Generator 555


Pulse Generator project will generate a frequency in up to 180 KHz which can form a good test gear project.  This project is based on the classic 555 timer IC.


  • Input : 5-12 VDC Max @ 40 mA
  • Provides Square Waves
  • Range : Jumper selectable and preset tunable range of 1 Hz to 180 KHz
  • Power-On LED indicator
  • Berg connector for easy connection
  • Four mounting holes of 3.2 mm each
  • PCB dimensions 47 mm x 40 mm

Pulse Generator 555 – [Link]

NE555 timer sparks low-cost voltage-to-frequency converter


by Gyula Dioszegi @ edn.com:

In 1971, Signetics—later Philips—introduced the NE555 timer, and manufacturers are still producing more than 1 billion of them a year. By adding a few components to the NE555, you can build a simple voltage-to-frequency converter for less than 50 cents. The circuit contains a Miller integrator based on a TL071 along with an NE555 timer (Figure 1). The input voltage in this application ranges from 0 to –10V, yielding an output-frequency range of 0 to 1000 Hz. The current of C1 is the function of input voltage: IC=–VIN/(P1+R1).

NE555 timer sparks low-cost voltage-to-frequency converter – [Link]

Capacitance Meter


by ThomasVDD @ instructables.com:

Capacitors are vital components in electronics, but sometimes they are broken, or the value printed on the cap has become unreadable. Because my multi-meter does not have a capacitance measurement, I decided to make one!

The principle of measuring capacitance is quite simple. The voltage of a capacitor charging through a resistor increases with time T. The time it takes to reach a certain voltage, is related to the values of the resistor and capacitor. In this project, we’ll use a 555 timer circuit as a monostable multivibrator. If that sounds like some dark magic to you, don’t worry, it’s quite straightforward. I’ll refer to the the Wikipedia page for the details, as we’ll focus on the things we really need: the schematic and formula. The time in which the capacitor C charges through the resistor R is given by: T = ln(3) x R x C = 1.1 RC. If we know the value of the resistor and the time, we can calculate the capacitance: C = T / 1.1R.

Capacitance Meter – [Link]

Emon-server – 555 Timer as power usage sensor


by dkroeske @ github.com:

A cheap 555 timer chip acting as Schmitt trigger combined with a phototransistor or LDR is taped to the ‘flashing light’ or ‘pulsing magnet’ on the electricity meter. The output of the 555 timer chip is connected to one of the GPIO pins on the Raspberry Pi. A Python script (executing in the background) recording 555 events is calculating actual energy usage [e.g. Watt] every time the 555 is signaling and stores epochs in an SQLite3 database. From this, another Python script (executed from e.g. cron) generates all kinds of energy usage information (e.g. kWh or kWday or whatever). Using Node.js (running on the same Pi) all data is ‘RESTified’ enabling spreading out to the W3. To maintain privacy JSON web tokens are required every time the service is queried. Oh, and there is also a Pimatic plugin available (here)

Emon-server – 555 Timer as power usage sensor – [Link]

Dog Repellent Ultrasonic Circuit 2



When we hear the word “Ultrasonic” we often refer it to bats and dolphins communication. Technically, “Ultrasonic” applies to sound that is anything above the frequencies of audible sound, and includes anything over 20kHz. Frequencies used for medical diagnostic ultrasound scans extend to 10 MHz and beyond. This dog repellent ultrasonic circuit will chase away angry dogs. It comprises of a 555 timer IC, a speaker/piezoelectric and a little ferrite transformer.

The main part of this circuit is a 555 timer IC. A 555 timer IC is an integrated circuit (chip) used in a variety of timer, pulse generation, and oscillator applications. The 555 can be used to provide time delays, as an oscillator, and as a flip-flop element. Derivatives provide up to four timing circuits in one package. You can use the 555 effectively without understanding the function of each pin in detail. Frequently, the 555 is used in astable mode to generate a continuous series of pulses, but you can also use the 555 to make a one-shot or monostable circuit. The 555 can source or sink 200 mA of output current, and is capable of driving wide range of output devices.

To use this circuit adjust 4k7Ω Resistor at resonance frequency of the piezo transducer for maximum amplitude of the repeller ultrasonic sound. At 11 KHz to 22kHz this can reach a value of 10Vpp and the buzzer is a passive one (without generator).

Note: Ultrasonic frequency must be set with a dog nearby.


4k7Ω Resistor
10uF Capacitor
10nF Capacitor
1k2Ω Resistor
4k7Ω Potentiometer
NC Push Button

Dog Repellent Ultrasonic Circuit 2 – [Link]

1 to 100 Seconds Timer


This project is a timer project and build around popular 555 Timer IC, It can be used for all application required a delay of up to 100 Seconds. Onboard board preset to adjust the required timer duration in range of of 1 to 100 Seconds, Tact switch SW1 to reset the timer and SW2 to start the timer. LED D3 works as power indicator and LED D2 to indicate timer operation.

Load can be connected to CN1 Screw Terminal, Out-put has both the operation normally Open and normally closed. Circuits works on 12V DC and consume approx. 100mA current. Very useful project can be used in various applications like water irrigation system, Kitchen timer etc.

Supply input 12 VDC @ 100 mA
Onboard start and reset tactile switch
Relay output: SPDT relay
Relay specification: 5 A @ 250 VAC
Relay state LED indicator
Preset adjustable range function
Power-On LED indicator
Screw terminal connector for easy relay output connection
Four mounting holes of 3.2 mm each
PCB dimensions 48 mm x 63 mm

1 to 100 Seconds Timer – [Link]

555 Timer Breakout Board Plus


A breakout board for the 555 timer exposing the leads astable or monostable implementation.

Hello, my name is Patrick Grady and I’m a highschool senior in the US. I’m an avid programmer and tinkerer and love anything related to electronics and computers.

This past winter I took a class in Digital Electronics and was introduced to the 555 timer. One of the most common applications of the 555 timer is the astable mode, which is unfortunately rather clunky to build on a breadboard. This 555 breakout board does more than expose the 555’s eight pins: it sets you up to run your 555 timer in astable mode with slots to insert two resistors and a capacitor of your choice. This board eliminates all the wiring for the 555 timer. The 555 Timer Breakout Board Plus will cut out the tedium of setting up the 555 timer and will allow hobbyists to dig straight in to their projects.

As a electronics hobbyist myself, I recognize the usefulness of this simple device, but also acknowledge its relevance is limited to the niche market of hobbyist electronics. If you want this device or think a friend could use it, please contribute to the campaign and buy a 555 timer breakout board!

555 Timer Breakout Board Plus – [Link]

DIY automatic water timer


Kyle wrote an article detailing his DIY automatic water timer:

Now that I have power and output figured out, I need to work on the control aspect. 555 timers are great for simple applications requiring up to a few minutes of delay. At 10 minutes, the RC values needed would boarder the danger zone of the timer not functioning correctly due to the leakage current of the capacitor and the small charge current of the resistor. I could have cascaded two or more timers together but that would be sloppy so I fell back on my trusty friend – the ATtiny micro controller. This would allow me to make changes as I want without redesigning the board.


DIY automatic water timer – [Link]