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Timers and Counters Circuits

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


Last Updated: November 22, 2021 02:42 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 can’t 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 can’t be activated again for 60 seconds. . . . Hobby Circuit designed by David A. Johnson P.E.-September, 2005

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
6 Models Available - Call 806-778-8407

Links to electronic circuits, electronic schematics and designs for engineers, hobbyists, students & inventors:

Laser Ray Sound -  This circuit produces a weird "Laser Ray" sound and flashes a white LED at approx 5Hz:__ 555-Timer

Laser Used as Vehicular Traffic Counter -  This is an illustration how a laser could be used to count traffic and measure the speed of each car passing through the sensor area. . . Circuit by David A. Johnson P.E.-January, 2007

Latch -  This circuit is a LATCH and remains ACTiVE when the push-button has been pressed for an iNSTANT and released.  __ 555-Timer

LCD clock based on AVR Attiny2313 -  The clock is working a 24 hour period.  The time is displayed in the format "hh: mm: ss" on the alphanumeric display of size 16 x 2 (columns x rows) with driver HD44780.  The use of a backlit display gives the impression of great visual at night.  instead, use a full stop or semicolon blink I used options available in the Bascom and created their own simple animation changing every second.  With such simple design to evaluate the accuracy of the clock is good.  Accuracy was +1 second / 48 hours.)  __ Designed by Szymon Dyja

LCD Clock/Calendar -  LCD Display with Date and Time, 12hr format.   __ Designed by Jose Pino

LCD Display with Minimum Mass Wireless Coupler -  its an adaption of the 2X 16 LCD project, by adding a fettite loop antenna, two resistors, and a capacitor.  Here the display shows the output of the 10 bit scanning voltmeter with Minimum Mass Wireless Coupler.    (ATtiny2313, AT90S2313)  __ Designed by Dick Cappels

LCD Frequency Counter -  This frequency counter module is intended as a "digital dial" frequency readout for portable QRP radio tranceivers.  it uses only six standard discrete logic IC 's, i.e.  no PIC  or other microcontroller, no programming to be done, etc.  The readout is designed to show kHz from the band edge with 100Hz resolution, i.e.00.0kHz to 99.9kHz.  The display updates ten times per second, which I have found to be a comfortable rate for tuning.  The current consumption is 1.4mA, very suitable for portable (battery powered) operation.  The size of the counter is 2.3 x 1.6 x 0.8 inches (58 x 41 x 20mm)  __ Designed by Hans Summers

LCD frequency counter (PIC16F84) -  Schematic Only __ Designed by © Peter Halicky  OM3CPH

LDR Pole Light Switch -  My vintage (62 year old) pole light has always been controlled by a timer—a source of continual frustration due the requirement of readjustment for the ever-changing seasons.  However, after knocking it over (I backed my car into it…) , I decided it was time for an update.  The circuit consists of a light dependent resistor __ Designed by Jim Keith

LED 7 segment Count Down Alarm -  Here I have added two fets for the time-out switch, it is like an electronic relay, just much more reliable it can be used to sound a big horn, or what ever you like.__ 

LED Clock -  12Hr LED clock using 16F628.  Also, schematic to build a Jumbo clock is included __ Designed by Jose Pino

LED Clock Using Pic (Microcontroller) -  Now you can always know the exact time.  With this design you can have an atomic clock in your room.  isn’t that great? Read on to know more.  First of all, it is not about any radioactive elements here.  This is about building a clock display that can get the time from the DCFF77 facilities__ 

LED Clock with Timer & Solar Panel Regulator -  This is a combination digital clock timer and solar panel charge controller used to maintain a deep cycle battery from a solar panel.  The timer output is used to control a 12 volt load for a 32 minute time interval each day.  Start time is set using 9 dip switches and ends 32 minutes later. __ Designed by Bill Bowden

LED Counter -  This circuit is the 12-bit binary counter which used 4040B.  The number of the pulses of the input can be confirmed by seeing it with the eyes by putting the light-emitting diode to the output of the counter.  it is the function only of it but it is useful.  Because it is the 12 bits, the highest rank counter __ Designed by Seiichi Inoue

LED Dice -  This circuit produces a random number from 1 to 6 on LEDs that are similar to the pips on the side of a dice.  When the two TOUCH WiRES are touched with a finger, the LEDs flash very quickly and when the finger is removed, they gradually slow down and come to a stop.  __ 555-Timer

LED Dimmer -  This circuit will adjust the brightness of one or more LEDs from 5% to 95%.  __ 555-Timer

LED Driver with 555 Timer -  This simple LED driver circuit allows us to drive up to seven LEDs by using a single NiMH (Nickel Metal Hydride) AA cell.  The circuit produces voltage pulses at a much higher level than the input supply voltage by pulsing the 220 uH inductor.  The inductor must be a high Q (Q>90) power inductor.  When the input is 1.25 V and the __ Designed by Popescu Marian

LED flasher with "Rising & Falling" Brightness -  Here is a Simple Circuit to give a Flashing LED, With a "Rising and Falling" Brightness.  it Uses the Sawtooth waveform from pins 2 and 6 to create the rise and fall.  The Resistor and LED on Pin 3 are Optional.  The 10K Potentiometer give a reasonable range of Speed.   __ Designed by G.L. Chemelec

LED Frequency Counter -  This counter was first known as the Modular Dial developed by Bill Carver, W7AAZ, and published in the Spring 1998 issue of Communications Quarterly. __ Designed by Web David White, WN5Y

LED matrix clock -  This LED Matrix Clock is a feasability study for a much larger project I built for my employer.  The intention was to prove to myself (and my employer!) that I was able to drive an LED matrix from a PC.  This is the first project I have made which is driven by a PC.  The clock uses 3 B64CDM8/B48CDM8 8x8 5mm LED Matrix modules from Nexus Machines, each having an onboard MAX7219 display driver chip.  These require an SPI serial interface, which I by toggling pins of the host PC's parallel port (printer port).  The small software application which drives the displays is written in DelphI 5 and runs on Windows NT 4.   __ Designed by Hans Summers

LED Relay Timer -  This circuit provides a visual 9 second delay using a 7 segment digital readout LED.  When the switch is closed, the CD4010 up/down counter is preset to 9 and the 555 timer is disabled with the output held high.  When the switch is opened,  __ Designed by Bill Bowden

LED Sand-Glass Timer -  This circuit simulates the old sand-glass timer.  A total of 32 LEDs create the effect of sand grains passing from the upper half of sand-glass to its lower half.  __ Electronics Projects for You

Light Controller High Side -  The diagrams are for 12V operation only and there are high side (common ground) and low side (common +12V) versions.  The low side version of the circuit uses an N Channel FET, the high side version of the circuit uses a P Channel FET.  N Channel devices tend to handle more current than P Channel devices, they are also less expensive.  The high side version of the circuit is useful when one side of the load has to be grounded __ Designed by G. Forrest Cook

Light Detector -  This circuit detects light falling on the Photo-cell (Light Dependent Resistor) to turn on the 555 and create a tone that is delivered to the speaker.  Pin 4 must be held below 0.7v to turn the 555 off.  Any voltage above 0.7v will activate the circuit.  The adjustable sensitivity control is needed__ 555-Timer

Lights timer -  Automatically turn off the lights after 10 minutes.  if you often forget to turn off the lights outside or at different places in the house, this circuit can be practical for you.  it can control two independent light switches with different turn off times.  Press the button once and the light turns on for the preset time.  Press again, and the light remains on forever.  Press for the third time, and the light turns off __ Designed by Peter Jakab

Light-Sensitive Alarm -  The circuit detects a sudden shadow falling on a light-sensor and sounds a bleeper for a short time (adjustable).  Normal lighting can be used, but the circuit will work best if a beam of light is arranged to fall on the light-sensor.  Breaking this beam will then cause the bleeper to sound __ Designed by John Hewes

Light-Sensitive Fire Alarm -  This light-sensitive fire alarm circuit is extremely sensitive, low-cost and easy to assemble even by a beginner.  it uses infrared photo transistor as fire sensor.  Circuit and working Circuit diagram of the light-sensitive...__ Electronics Projects for You

Line Powered 60hz Clock Generator -  This circuit is connected to the 120vac power line and transfers 60Hz clock pulses to a logic circuit.  The optoisolator used provides 5000 volts of isolation between the power line and the logic side of the circuit. . . Circuit by Dave Johnson P.E.-February, 1999

Linear Resistance-To-Time Conversion -  08/07/03  EDN Design Ideas:  Resistance-based transducers, such as strain gauges and piezoresistive devices, find common use in the measurement of several physical parameters.  For applications in which digital processors or microcontrollers serve for data acqui Design by Kaliyugavaradan and D Arul Raj, Anna University, Chennai, India

Linear Timer for General Use -  This simple timer can be used to control any electrical appliance that needs to be switched off after certain time, like a small heater or a boiler, provided the relay-switch parameters...__ Electronics Projects for You

LM324 Pulse Width Modulator -  Schematic only, no circuits description.   __ Designed by Tony van Roon  VA3AVR

Logic IC yields simple, wide-range timer -  08/01/97 EDN Design Ideas:  You can use a 4060B binary counter/oscillator to make a simple, accurate, long-delay timer.  The circuit offers longer times (milliseconds to hours] than you can achieve with common IC timers.  A positive logic level at the input holds the counters in the reset state and the output in the low state.  When the input goes low, the output goes high, forward-biasing D1 and "stalling" the oscillator Design by Harry Bissell Jr, Robotron Corp, Southfield, MI

Logic offers Complementary Switch Control -  12/06/01 EDN Design Ideas:  The complementary-switch controller in Figure 1 uses a few inverter gates to provide drive signals for the complementary switches.  Complementary-switch configurations find wideaspread use in synchronous-rectification circuits, charge pumps, full-bridge control circuits, and other circuits.  The circuit in Figure 1 provide as not only a complementary drive signal but also a deadtime delay Design by Yen-Hsu Chen, Analog Integrations Corp, Hsinchu, Taiwan

Long Delay Timer -  Suitable for battery-operated devices; Fixed 35 minutes delay __ Contact Flavio Dellepiane, fladello @ tin.it

Long Duration Timer -  in order to create a long duration timer the 556 IC teamed up with a binary divider can provide delays as much as 16 times that set by the time constant of the first timer.  You can use two 555 ICs  instead of the 556.  The first timer provides a delay of 7.5 minutes and the divided outputs give a delay of 15 min, 30 min, 1 hour __ Designed by Popescu Marian

Long Duration Timer -  This circuit can be used with a relay, as shown, or it can be used to drive a TRIAC.  if a TRIAC is used an opto-isolator should be used.  With the component values shown, the range of timed periods will be from about 10 seconds to about 1 hour.   __ Designed by © David Hoult

Long Period Computer Watch Dog Timer -  This circuit uses a simple 4060 IC oscillator/timer that is reset periodically by a computer.  Should the computer fail to send a pulse, the output changes state.  The time can easily be set from seconds to hours. . . Circuit by David Johnson P.E.-January, 1998

Long Time Period Automatic Timer -  As we have already published various timer based project like “Universal Timer”, “Appliance Timer” and many more.  Now here is also a timer based project but different in many aspect.  The project “Long Period Automatic Timer” offers automatic control of electric and electronics appliance up to long duration__ 

Low Distortion, Crystal Stabilized Oscillator -  Variation on the classic sine-wave Wien-bridge oscillator.  The op amp to the left forces a symmetric signal to develop across the bridge, while the negative tempco of the lamp filament stabilizes the amplitude of oscillation by the right-side section.  __ Linear Technology/Analog Devices App Note, Jun 21, 2011

Low Frequency 555 Oscillator -  if the capacitor is replaced with an electrolytic, the frequency of oscillation will reduce.  When the frequency is less than 1Hz, the oscillator circuit is called a timer or "delay circuit.  " The 555 will produce delays as long as 30 minutes but with long delays, the timing is not accurate.  __ 555-Timer

Low Power Oscillators -  This page has two unusual two-transistor oscillators.  I set the component values for a low frequency application.  Both circuits draw only about 1 micro amp of current. . . Circuit by David A. Johnson P.E.-December, 2002

Low side PWM Motor/Light Controller -  The diagrams are for 12V operation only and there are high side (common ground) and low side (common +12V) versions.  The low side version of the circuit uses an N Channel FET, the high side version of the circuit uses a P Channel FET.  N Channel devices tend to handle more current than P Channel devices, they are also less expensive.  The high side version of the circuit is useful when one side of the load has to be grounded __ Designed by G. Forrest Cook

Low Voltage , High Current Time Delay -  in this circuit a LM339 quad voltage comparator is used to generate a time delay and control a high current output at low voltage.  Approximatey 5 amps of current can be obtained using a couple fresh alkaline D batteries.  Three of the comparators are wired in parallel to drive a medium power PNP transistor (2N2905 or similar) which in turn drives a high current NPN transistor (TiP35 or similar).  The 4th comparator is used to generate a time delay after the normally closed switch is opened __ Designed by Bill Bowden

Low-Cost Stopwatch -  Here is a simple circuit of a stopwatch that can count up to 99 seconds.  The circuit uses CD4060, CD4013, CD4033, LTS543 and some discrete components.  A crystal-controlled oscillator generates 1Hz...__ Electronics Projects for You

Low-distortion Audio-range Oscillator -  Generates very low-distortion sine waves up to 1V RMS No thermistors required No settling time __ Contact Flavio Dellepiane, fladello @ tin.it

Low-Power Interrupt Updates Real-Time Clock -  07/07/94 EDN Design Ideas:  Some µP-based systems need a real-time clock.  The µP's built-in timer can do the work, but it usually requires several milliamps of current to keep the timer running.  if the main power drops, the clock requires a backup battery to operate.  The size of the backup battery Design by Yongping Xia, EBT Inc, Torrance, CA

LTC Design Note: Robust 10MHz reference clock input protection & distributor for RF systems -  07/31/14  LTC Design Notes: Design a protected 10MHz reference input without degrading phase noise. Design by Michel Azarian

LTC Design Note: Uncompromised clocking solution for 16bit 2.5Gsps DAC -  EDN Design Ideas:  01/30/2017    System performance & phase noise depend on clock as much as DAC quality Design

LTC6945 Wideband Point-to-Point Radio Local Oscillator -  The LTC6945 is a high performance, low noise, 6GHz phase locked loop (PLL) , including a reference divider, phase frequency detector (PFD) with phase-lock indicator, charge pump, integer feedback divider and VCO output divider.  The part features a buffered, programmable VCO output divider with a range of 1 through 6.  The differential, __ Linear Technology/Analog Devices App Note, Jan 16th 2012

LTC6946-2 Driving a Passive Downconverting Mixer -  The LTC6946 is a high performance, low noise, 5.7GHz phase-locked loop (PLL) with a fully integrated VCO, including a reference divider, phase-frequency detector (PFD) with phase-lock indicator, ultralow noise charge pump, integer feedback divider, and VCO output divider.  The charge pump contains selectable high and low voltage__ Linear Technology/Analog Devices App Note, Jan 16th 2012

Lua Railway clock WiFi ESP8266 -  Swiss railway clock is precise digital wifI clock.  it's a miniature web server and very good demo for ESP8266 & Lua fanclub.
By mapping ports of your router, you can connect to it from anywhere on the world.  This clock uses Lua software and
trendy vector graphics format SVG with animations.  The clock is particularly interesting for its graphic design.  in terms of program, it using
synchronization the time from an external NTP server.   Thanks to this, clock is quite fast and precision, which was my goal. __ Designed by © Pavel Janko

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Got Designs?
Please eMail
if you want me to link to and/or post your original design Thanks.

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

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