Tag Archives: Timer

230 VAC Timer


Classic AC 230 V Timer project can be used in all application requiring a timer of up-to 3 Minutes to operate or control any AC mains load of up-to 200 Watts. This project is based on the Classic 555 Timer IC, triggering a TRIAC. Input and Output is Optically Isolated.


  • Supply input 12 VDC
  • Mains supply input 240 VAC or 120 VAC ( Read Note for 120V/230V AC)
  • Output: up-to 200 Watt
  • Optically isolated Input / Output
  • Onboard start and reset tactile switch
  • Timer On LED
  • Preset adjustable and jumper selectable for range
  • Power-On LED indicator
  • Screw terminal connector for easy mains supply input and load connection
  • Four mounting holes of 3.2 mm each
  • PCB dimensions 46 mm x 91 mm

230 VAC Timer – [Link]

2 Digit 99 Seconds Timer


2 Digit Count Down Timer is a utility Count Down timer project for upto 99 seconds of countdown time. This project can find many uses in your shack and home. The relay output remains on during the Count Down period, allowing you to interface load or alarm that you want to keep it on for a certain amount of time (in seconds).


  • Microcontroller based design for greater accuracy and control
  • Power supply input 12 VDC 200 mA
  • Two 0.5″ display segments to display time
  • 12V SPDT (Single Pole Double Throw) relay for alarm use
  • Single key start and dual key alarm time set function
  • Power and Relay-On LED indicator
  • Terminal connectors for connecting power supply input and relay output to the PCB
  • Onboard regulator for regulated supply to the kit
  • Crystal resonator based design for better accuracy
  • PCB dimensions 72 mm x 81 mm

2 Digit 99 Seconds Timer – [Link]

FUN but REAL: Manually or lying down


Yes, these are your options when you want to set time relay of 12.51 series from Finder producer.

Italian producer accommodated less active installers that can now set, resp. program time relay also lying down. Of course, something for something – you need to have a computer but luckily it is something that almost any installer has in his pocket – a smartphone supporting NFC. So, how does it work and what needs to be done:
● Select the appropriate moment – it can be even in the middle of the night
● Choose a comfortable bed – empty one would be the best, so you don’t get distracted by anything
● Put on a comfy clothes – even dungarees, but in that case we suggest covering the bed with polythene
● For the first time, you need to be able to connect to wi-fi from the bed so you can easily download free app FINDER Toolbox from the GooglePlay.

Lay comfortably down – the most well-known and used positions are these four:

  • on the back
  • on the belly
  • on the side version L (on the left)
  • on the side version R (on the right)

In case of using a polythene, you can use all four positions also with legs on the pillow

  • The work itself is just a “game on the phone”
  • Start the game FinderToolbox. Set when and for how long you want that thing to be on and save the settings.
  • The most difficult phase of programming is about to get started. Get off the bed, come to the time relay and touch the actual time relay with your smartphone – that’s when the settings will be transferred to relay

Time relay 12.51 looks like an ordinary time relay on a DIN rail with big nice display backlight – blue signs on white background that effectively shows the necessary information.

Relay also allows programming with joystick (thus manually). This mode is for those who cannot relax while working.

FUN but REAL: Manually or lying down – [Link]

Headlight Modulator for Motorcycle


William Dudley @ dudley.nu has designed a motorcycle headlight modulator based on 555 timer IC and photoresistor. A headlight modulator will make the headlight to pulse during the day and be steady at night. He writes:

Unhappy with a headlight modulator I purchased, I decided to make my own. Even though it would be a trivial programming project to use an Arduino Teensy or similar to do this, I decided to do it the “old fashioned” way, using a 555 timer. The 555 is a clever chip; not only will it supply the oscillator for the flashing effect, it has a reset pin that can be used to force the output to a known state (low) when (other circuitry tells it that) it’s dark outside.

Headlight Modulator for Motorcycle – [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]

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]

Delay using 8051 Timer

The major component of this circuit is Microchip’s SST89E54RDA-40-C-PIE, which is a pin-for-pin compatible with typical 8051 microcontroller devices. It has a built-in timer used to produce accurate time delay. The light emitting diode (LED) is connected through the 330Ω resistor to indicate the time delay. The blinking LED switches ON for 1ms and switches OFF for 1ms that indicates toggling from LOW to HIGH and HIGH to LOW. Output PIN P2.2 can be connected to an oscilloscope to generate a square wave.

SST89E58RDA-40-C-PIE comes with 72 Kbyte of on-chip flash EEPROM program memory that is partitioned into 2 independent program memory blocks. The primary Block 0 occupies 64 Kbyte of internal program memory space and the secondary Block 1 occupies 8 Kbyte of internal program memory space. The 8-Kbyte secondary blocks can be mapped to the lowest location of the 64 Kbyte address space; it can also be hidden from the program counter and used as an independent EEPROM-like data memory. In addition to the 72 Kbyte of EEPROM program memory on-chip and 1024 x8 bits of on-chip RAM, the devices can address up to 64 Kbyte of external program memory and up to 64 Kbyte of external RAM.

This design integrating Microchip’s SST89E54RDA-40-C-PIE would be used if high-accuracy, precision and timing resolution of timed events are required to activate or deactivate control outputs based on programmed time intervals. Time delay applications include pump control, food processing, and packaging control where precise ON/OFF control is necessary.

Delay using 8051 Timer – [Link]

Arduino Chess Clock


by benhur.goncalves @ instructables.com:

Hey folks! After making an Arduino smartwatch just last week, I received many complaints,or tips, to use a RTC (real-time clock) module. That’s because the Arduino timer is not very precise, it can lose a couple a minutes along a full work day. Luckly, I had one of those modules at my home, I decided to give it a try. However, I faced some challenges along the way, as I can show you here.

Arduino Chess Clock – [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]