Tag Archives: Timer

PIC16F628A Programmable Digital Timer

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Raj Bhatt shared another project with us. This time is a programmable digital timer with relay switch based on PIC16F628A.

Programmable relays find use in numerous automation applications such as automatic street light control, watering and pump control, HVAC, home automation, power plants automation in industries, etc. This article describes how to build a fully functional, one-channel programmable relay switch using the PIC16F628A microcontroller. It allows you to set both ON and OFF time. The maximum time interval that you can set for on and off operations is 99 hours and 59 minutes. Another interesting feature of this project is it offers cyclic option, which means you can choose to run it in a continuous loop of ON and OFF cycles. The device can be programmed through 4 push switches. The programming menu and device status are displayed on a 16×2 character LCD. The timing resolution of this relay timer is 1 minute. The timer also saves the user inputs to its internal EEPROM so that it can retain these values after any power supply interrupt.

PIC16F628A Programmable Digital Timer – [Link]

Reverse engineering the popular 555 timer chip

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Ken Shirriff wrote an article on reverse engineering the 555 timer chip, He writes:

This article explains how the LMC555 timer chip works, from the tiny transistors and resistors on the silicon chip, to the functional units such as comparators and current mirrors that make it work. The popular 555 timer integrated circuit is said to be the world’s best-selling integrated circuit with billions sold since it was designed in 1970 by analog IC wizard Hans Camenzind[1]. The LMC555 is a low-power CMOS version of the 555; instead of the bipolar transistors in the classic 555 (which I described earlier), the CMOS chip is built from low-power MOS transistors. The LMC555 chip can be understood by carefully examining the die photo.

Reverse engineering the popular 555 timer chip – [Link]

DC Motor Speed and Direction Controller

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DC Motor Speed and direction controller project based on L293D H-Bridge and 555 Timer IC. 555 Generate PWM and L293D works as output driver. The 293D provides bidirectional drive current up to 600mA a voltage from 5V to 12V. L293D includes the output clamping diodes for protections.

Specifications 

  • Supply 5 to 12 V
  • Inhibit facility/enable
  • PWM Frequency 5KHz Maximum
  • High Noise immunity
  • Over temperature protection
  • Capable of delivering output current up to 600 mA per channel

DC Motor Speed and Direction Controller – [Link]

ATTiny25 based tea timer

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Michael @ acidbourbon.wordpress.com has built the “perfect” tea timer project. He wrote a post on his blog detailing its assembly:

Maybe you just drink coffee. Then this article is not particularly interesting for you. But if you like a cup of black or green tea once in a while you might know the problem: You prepare your tea and you let it stand for a minute too long. Then it is bitter. So the next time you use the timer functionality of your smartphone … unlock the screen, open the timer app, enter something like “3:00″ (minutes), press start, pour boiling water over the tea, wait. Then your phone beeps like crazy while you are fumbling around with the hot and wet teabag you want to dispose of. Finally you unlock your beeping phone with your wet fingers, open the timer app again and silence it. Pure stress.

ATTiny25 based tea timer – [Link]

555 Timer Teardown

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Ken Shirriff has done a detailed teardown of the popular 555 timer IC. Let’s take a look inside this little chip:

Given the popularity of the 555 timer, I thought it would be interesting to find out what’s inside the 555 timer and how it works. While the 555 timer is usually sold as a black plastic IC, it is also available in a metal can, which can be cut open with a hacksaw revealing the tiny die inside.

555 Timer Teardown – [Link]

Programmable CW Morse beacon

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Marko Pavlin has designed a Mini USB dongle with STM32F0xx that is connected to USB and controlled via command line interface.

Mini USB dongle with STM32F0xx is suitable many for simple, mini projects. I attached speaker to Timer14 PWM output (Pin PA6) and LED (or optocoupler connected to PTT) to GPIO pin PA0
The provided software is based on USB Virtual Com Port (VCP) device. The setup is done with command line interface using terminal from any PC. The setup is stored in the internal flash and PC is not required for normal operation. The mini beacon keyer can be used when powered with 5V.

Programmable CW Morse Keyer – [Link]

230 VAC Timer

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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.

Specifications 

  • 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

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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).

Specifications

  • 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

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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]