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Timers and Counters Circuits

Timers & Counters:  #'s - A      B - D      E - L      M - S      T - Z


Last Updated: October 24, 2017 02:55 PM

Circuits Designed by Dave Johnson, P.E. :
Motorized Duck Decoy Timer -  I received a nice email from a duck hunter.  He uses some motorized decoys to lure ducks into his line of fire.  However, the battery powered decoys only have an on/off switch so once turned on; the decoy flaps its wings or paddles around continuously.  The hunter wanted a more realistic motion, which would power the motor for say 10 seconds, then stop for another 10 seconds before starting up again.  The simple circuit below should work well for his application . . . Hobby Circuit designed by David Johnson P.E.-September, 2011

On/Off Flip/Flop Circuit with Automatic Timeout -  This circuit is ideal when a device needs to be turned on and off with a single pushbutton switch, but also needs to turn itself off after some period of time.  With the components shown, the output will stay on for only about 20 seconds. . . Circuit by David A. Johnson P.E.-May, 2012

On/Off Latch Circuit with 2 Second Delay -  A Discover Circuits visitor needed a latch circuit which could operate using a power supply voltage ranging from 3v to 24v.  He wanted to use a tiny pushbutton switch to turn on and off power to a load.  However, he wanted a 2 second delay between the switch activation and the state change of the output. . . Circuit by Dave Johnson P.E.-June, 2013

On/off Pushbutton Switch with 30 Minute Timeout -  I received an email from a Discover Circuits visitor.  He wanted to control power to a LED camping light he was building.  He wanted to turn the light on and off with a small pushbutton switch.  He also wanted a timer so the light would not stay on longer than 30 minutes at a time.  It seems that his kids often turned lights on when going to bed and then forgot to turn them off. . . Circuit by David Johnson P.E.-January, 2012

Poor Man's Timer -  Often during testing of certain equipment and components, you would like to keep track of the elapsed time in hours, minutes and seconds.  There are some nice commercial digital timers and counters available for just this sort of application.  However, . . . Hobby Circuit designed by Dave Johnson P.E.-August, 2008

Press & Hold Latching Circuit -  A Discover Circuits visitor needed a latch circuit which could operate using a power supply voltage ranging from 3v to 24v.  He wanted to use a tiny pushbutton switch to turn on and off power to a load.  However, he wanted a 2 second delay between the switch activation and the state change of the output . . . Hobby Circuit designed by David Johnson P.E.-June, 2013

Pushbutton Activates Service Request Beeper -  A single press of a pushbutton switch turns on a beeper for one second but canít be activated again for 60 seconds.. . . Circuit by David A. Johnson P.E.-September, 2005

PWM Motor Controller uses a 555 Timer -  Using a CMOS version of the 555 timer, this circuit can be used to control the speed of a motor by adjusting the duty cycle of the pulses sent to the motor . . . Hobby Circuit designed by David Johnson P.E.-February, 2007

Service Request Beeper -  A single press of a pushbutton switch turns on a beeper for one second but canít be activated again for 60 seconds. . . . Hobby Circuit designed by David A. Johnson P.E.-September, 2005

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Pacer clock saves subroutine calls -  11/10/05 EDN Design Ideas:  Time-delay routine requires no subroutine calls, avoids stack-overflow hazards __ Circuit Design by Enver Torlakovic, Willmot, New South Wales, Australia

Panel-mounting clock -  I hope you can see by the ruler that this clock is very, very small.  it was built to fit inside the front panel of a radio tranceiver (yet to be built) , alongside my panel mounting radio frequency counter.  The switch on the right is used to set the time, it's a 3 position switch.  in the middle, the clock runs normally, push the switch up and the minutes start incrementing at a rate of about 2 per second, push the switch down and the time goes up a lot faster __ Designed by Hans Summers

PC Timer -  Primarily intended for installation into a desktop PC, this versatile timer with adjustable time output provides controlled Ďoní time for PC peripherals like printers, scanners and desktop reading lamps.  As it...__ Electronics Projects for You


PCB countdown timer -  This is a countdown counter based on ATtiny2313, primary developed for my PCB exposure box, but it can be used for other purposes too.  The counting range is between 1 and 90 minutes and it can be adjusted with up or down buttons (high and low in the pictures).  After the desired time is set, the countdown starts by pressing the start/stop button (on/off in the pictures).  By pressing the same button we can interrupt the counting at any time we want.  __ AVR Projects Dim

PC-Based Timer -  Timers are very useful both for industrial applications and household appliances.  Here is a PC-based timer that can be used for controlling the appliances for up to 18 hours.  For control, ...__ Electronics Projects for You

PC's parallel port to program a clock source -  12/07/04 EDN Design Ideas:  This design idea shows how you can use Linear Technology's LTC6903 programmable oscillator as a clock source for direct-digital synthesis, data conversion, switched-capacitor filtering, clock, and voltage-controlled oscillator circuits.  The LTC6903 operates from 2.7 to 5.5V with modest power consumption and can produce clock signals at frequencies of 1 kHz to 68 MHz __ Circuit Design by William Grill, Honeywell BRGA, Lenexa, KS

Peak Hour Timer -  Electrical appliances like refrigerators and air-conditioners consume heavy current if the line voltage drops during the peak hours between 6 pm and 9 pm.  if there is no low-voltage cut-off in...__ Electronics Projects for You

Pedometer -  Pedometer has a range of 9.950 meters with2-digits.  Slip it in pants pocket for walking and jogging __ Contact Flavio Dellepiane, fladello @ tin.it

Perfect Sinus 1 kHz Oscillator -  Schematic only __ Designed by va3iul

Period timer for aquarium, sprinklers & More -  This is a simple one-valve irrigation controller made for our greenhouse.  The code contains a software real-time clock (RTC) and a multiplexed 8-digit LED display and keyboard you can use in other projects.  Turn on the sprinkler or the aquarium lighting for the same period of the day.  You can choose to operate the output by every 2nd, 3rd day only.  There is a manual start/stop button to immediately turn on or off the output, and a disable button to completely turn off automatic operation __ Designed by Peter Jakab

Periodic Timer -  A switched timer with equal make and equal space periods timing adjustable from over 6 minutes to 38 minutes.   __ Designed by Andy Collison

Periodically on-off Mosquito repellent -  Here is a circuit that automatically switches on and off the mosquito repellent after preset time interval, thus controlling the release of toxic vapours into the room.  __ Electronics Projects for You

Person Counter -  The integrated circuit is a 4516 up/down counter.  Diode 2 determines the count direction.  The value of the resistors Rí depends on the type of diode used. (You will probably need resistors in the range 100k to 1M.) When entering the room, the beam illuminating diode 1 must be cut first.  This causes the counter to count UP one.  if (when a person leaves the room) the beam illuminating diode 2 is cut and while this beam is still cut the beam illuminating diode 1 is cut, the counter will count down one.  The output can be used (with a relay and driver) to switch on a light when a person first enters the room and then to switch the light off when the last person leaves the room (maximum number of people, 15).   __ Designed by © David Hoult

Photo Timer -  Time is set by potentiometer R2 which provides a range or 1 sec.  To 100 seconds with timing capacitor C1 of 100uF.  The output at pin 3 is normally low and the relay is held off.  A momentary push on switch S1 energies the relay which is held closed for a time 1.1 X (R1+R2)  __ Contact Ravi Sumithraarachchi

Photo-Counter -  You can use this gadget to detect whether somebody opened your cupboard or drawer in your absence.  The gadget is small and highly power-efficient.  The small size means it can be...__ Electronics Projects for You

Phototimer Controls Load -  04/18/02 EDN Design Ideas:  in industrial and home applications, the need sometimes exists for a device that, after activation by some physical effect, such as light, temperature, or sound, switches a load on for a predetermined time.  The load, such as a lamp, motor, solenoid, or heater, usually derives its power from the ac line __ Circuit Design by Abel Raynus, Armatron International, Melrose, MA

PIC Clock -  Last summer vacation, I had an opportunity to be in dad's hobby workshop and decided to have a look at my pending projects. (I am no longer a science student but now in School of Fashion Technology for my BS Degree) I realized that I had a lot of parts in boxes that I ordered and must be utilized! !  I decided to complete one more project as all that was to be done was to design a board. __ Designed by Nina Gajjar

PIC Counter -  Frequency Counter project detailed here is based on PIC 18F4550 for which design and firmware/software support is given by Fox Delta Team.   There are many PIC  based frequency counters out there but this one will stand apart from others. __ Designed by Nina Gajjar

PIC Frequency Counter -  Programmable frequency meter with PIC 16F84 and UPB1505 prescaler __ Designed by YO5OFH, Csaba Gajdos

PIC frequency counter operating up to about 50 MHz (7 segment) -  EEPROM is useful for storing long term data such as data logger information and this PIC  microcontroller EEPROM project saves the temperature from an LM35DZ IC to the PIC 's internal long term data storage area.   The project follows on from the last project using the virtually the same hardware. __ Designed by John Main

PIC Toc-A Simple Circuit Digital Alarm Clock -  What Has less than 20 parts and can wake you in the morning? it's the Pic-Toc alarm clock and it's really easy to build.__ SiliconChip

PIC Tock Video Clock -  PIC -Tock is a video clock using a PIC 16C61.  in the tradition of Marv Newland's "BambI Meets Godzilla", there is far too much ROM space spent on credits, which are smooth-scrolled horizontally on the bottom of the screen.   __ Designed by Eric Smith

PIC16F628 Digital Clock Timer -  This clock timer uses a PIC 16F628 microcontroller to display 3 and 1/2 digit time and control an external load.  The clock includes a calendar with leap year and optional daylight savings adjustments.  The timer output can be set from 1 to 59 minutes and manually switched on and off.  The clock also has a correction feature that allows an additional second to be added every so many hours to compensate for a slightly slow running oscillator.  The oscillator uses a common 32.768 KHz watch crystal and the frequency can be adjusted slightly with the 24pF capacitor on the right side of the crystal __ Designed by Bill Bowden

PIC16f84 Miniature Real Time Controller -  Build a simple real-time controller with PIC 16F84 running at low power X-tal 32, 768Hz.  Daily scheduler for 6-channel resided in 64-byte EEPROM can easily be pre-programmed using Nigel PicProg __ Designed by Wichit Sirichote

PIC16F873 Digital Clock -  On this page, I will introduce the PIC  controled circuit which is the heart of Ultra High Accuracy Digital Clock.  For the details of the clock, refer to "Ultra High Accuracy Digital Clock version 2". 
As for PIC , PIC 16F873 is used in the relation of the input-output port.  Also, to make a circuit compact, CPLD is used for the peripheral.   __ Designed by Seiichi Inoue

PIC-based Flexitimer Mk.4 -  Here's a new and enhanced version of a very popular project: an easily-programmed low-cost electronic timer module.  it's compact, easy to build and offers a choice of either a single on period or continuous on/off cycling with independently programmable periods.__ SiliconChip

PLD Implements Fast Four-Phase Clock Generator -  10/27/94  EDN Design Ideas:  The circuit in Fig 1a can clock pipelined logic in PLDs by an external agent at one-half the usual frequency.  You can use this circuit when designing pipelined ALUs and switched-capacitor circuits.  I used this circuit to drive a 40M-sample/sec CMOS flash __ Circuit Design by Said Jackson, Hamburg, Germany

Police Lights -  These two circuits flash the left LEDs 3 times then the right LEDs 3 times, then repeats.  The only difference is the choice of chips.  __ 555-Timer

Police Siren -  The Police Siren circuit uses two 555's to produce an up-down wailing sound.  The first 555 is wired as a low-frequency oscillator to control the VOLTAGE CONTROL pin 5 of the second 555.  /.  __ 555-Timer

Poor Man's Timer -  Often during testing of certain equipment and components, you would like to keep track of the elapsed time in hours, minutes and seconds.  There are some nice commercial digital timers and counters available for just this sort of application.  However, . . . Hobby Circuit designed by Dave Johnson P.E.-August, 2008

Positive Edges Trigger Parabolic Timebase Generator -  07/28/11  EDN Design Ideas:  Generate sawtooth, quadratic-parabolic, and cubic-parabolic signals.   __ Circuit Design by MariŠn ätofka, Slovak University of Technology, Bratislava, Slovakia

Positive Trigger Timer -  This 555 timer is designed unusually to give a positive output through a control over its reset pin.  Usually the timer IC 555 is triggered by applying a negative going pulse to its trigger pin 2.  This timer is triggered through a positive pulse in its reset pin.  in the monostable mode IC 555 starts timing cycle when a negative __ Designed by D Mohankumar

Power Indicator for the Water Softener -  This power indicator circuit is intended to be used as an extension for the water softener.  it might be easier to just place a LED but it is better to make a rectifier that detects the presence of the 15 kHz signal generated by the 555 IC .  Water Softener Power indicator Schematic The rectifier is connected at the water __ Designed by Popescu Marian

Power Pulser -  The idea behind this multipurpose power pulser is very simple.  As shown in the circuit (Fig.1) , it uses a low-frequency oscillator to drive a voltage regulator.  Timer chip LM555 (IC 1)...__ Electronics Projects for You

Power Resumption Alarm -  Here is a simple power resumption alarm circuit that can be fixed inside the switch box itself.  it gives beeps when the power resumes after a power failure.  This circuit is ideal to monitor battery chargers, since the long duration power failure may sometimes remain unnoticed.  The circuit is too simple and derives power supply __ Designed by D Mohankumar

Power Resumption Alarm & Low-Voltage Protector -  The circuit described here protects your electrical appliances like AC motors from damage due to low voltage at power-on.  it remains standby without giving power to the load after power resumes....__ Electronics Projects for You

Powering a Project Negative Voltage -  The safest way to power a project is with a battery.  Use 4 x AA cells in a holder or a 9v battery if you only want to use the project for a short period of time.  if you want to use a 555 project for a long period of time you will need a "power supply.  ".  __ 555-Timer

Power-Off Time Delay Relay -  The two circuits below illustrate opening a relay contact a short time after the ignition or ligh switch is turned off.  The capacitor is charged and the relay is closed when the voltage at the diode anode rises to +12 volts.  The circuit on the left is a common collector or emitter follower and has the advantage of one less part since a resistor is not needed in series with the transistor base.  However the voltage across the relay coil will be two diode drops less than the supply voltage, or about 11 volts for a 12.5 volt input. __ Designed by Bill Bowden

Power-On Time Delay Relay -  Here's a power-on time delay relay circuit that takes advantage of the emitter/base breakdown voltage of an ordinary bi-polar transistor.  The reverse connected emitter/base junction of a 2N3904 transistor is used as an 8 volt zener diode which creates a higher turn-on voltage for the Darlington connected transistor pair.  Most any bi-polar transistor may be used, but the zener voltage will vary from about 6 to 9 volts depending on the particular transistor used.  Time delay is roughly 7 seconds using a 47K resistor and 100uF capacitor and can be reduced by reducing the R or C values. __ Designed by Bill Bowden

Precisely measure settling time to 1 ppm -  03/04/10  EDN Technical Article: intense, extensive, and protracted effort yields a measurement circuit with 20-bit resolution.  nstrumentation, function generators, inertial navigation systems, ATE (automatic test equipment) , medical apparatus, and other precision applications now require 18-bit converters.  The resolutions of these converters are so precise that measuring various performance parameters is difficult.  DACsí dc specifications are relatively easy to verify, but their ac specifications require more sophisticated approaches to produce reliable information.  A DACís settling time is the elapsed time from an input code application until the output remains within a specified error band around the final value.   __ Circuit Design by Jim Williams, EDN's most revered contributor, passed away in June 2011 after a stroke.  He was 63.

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Timers & Counters:  #'s - A      B - D      E - L      M - S      T - Z


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