Electronic Circuits and electronic circuits, electronic schematics plus an extensive resource for hobbyists, inventors and engineers

DiscoverCircuits.com, has 45,000+ electronic circuits, cross-referenced
into 500+ categories.    We have searched the web to help you find quick design ideas.
We make every effort to link to original material posted by the designer. 
Please let us if you would like us to link to or post your design.

HOME Schematics Index Hobby Corner Dave's Circuits Electronic Resources Contact Info
Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches

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

Timers and Counters Circuits

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


Last Updated: January 01, 2018 04:02 AM

Circuits Designed by Dave Johnson, P.E. :

Front Desk Service Beeper -  This device functions like a lobby desk service request bell.  A short beep is sounded whenever the large pushbutton on top of the device is pressed.  Once pressed, the device will not make another beep until at least 2 minutes of time has elapsed . . . Hobby Circuit designed by David A. Johnson P.E.-September, 2005

Garage Door Timer -  The circuit below is designed to automatically close a garage door, if it was left open for a long period of time.  A reed relay and magnet combination sense when the door is fully open.  An ultra low power voltage comparator oscillator and two 74HC4040 ICs are used to generate the time delay. . . Circuit by Dave Johnson P.E.-May, 2011

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

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

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

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

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
6 Models Available - Call 806-368-7747

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

Digital Game Show Timer -  Several Game Show timers included, scroll to find this one.  Using only two CMOS IC packages, this game show buzzer performs well enough to be on TV!  The first contestant to press his button locks out the other two contestants.  The design is completely asynchronous and "fair".  Other logic families will also work and any appropriate power supply is fine.  For simplicity, a single-chime doorbell is used for the aural indicator.  if a buzzer is preferred, use double pole pushbuttons with the second poles connected to activate the buzzer.  Simply connecting a buzzer in place of the doorbell will work but the buzzer will sound until the reset switch is pushed.   __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Digital LED Clock & Timer -  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

Digital 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

Digital Step-Km Counter-Max. Range: 9,950 meters -  This circuit measures the distance covered during a walk.  Hardware is located in a small box slipped in pants' pocket and the display is conceived in the following manner: the leftmost display D2 (the most significant digit) shows 0 to 9 Km.  and its dot is always on to separate Km.  from hm.  The rightmost display D1 (the least significant digit) shows hundreds meters and its dot illuminates after every 50 meters of walking.__ Learning Electronics

Digital Stop Watch -  Here’s a digital stop watch built around timer IC LM555 and 4-digit counter IC with multiplexed 7-segment output drivers (MM74C926).  IC MM74C926 consists of a 4-digit counter, an internal output latch, npn...__ Electronics Projects for You

Digital Stopwatch -  times up to an hour in tenths of a second - __ Contact P. Townshend - EduTek Ltd

Digital Stopwatch 0-60sec -  By using the same circuit of the Digital Stopwatch 0-99sec , we can add an AND gate, and transform the 0 – 99sec stopwatch to a 0 – 60sec stopwatch. __ Designed by Koukos Konstantinos, Tsormpatzidis Dimitrios - Aristotle University of Thessaloniki

Digital Stopwatch 0-99sec -  By using the same circuit of the Digital Stopwatch 0-99sec , we can add an AND gate, and transform the 0 – 99sec stopwatch to a 0 – 60sec stopwatch. __ Designed by Koukos Konstantinos, Tsormpatzidis Dimitrios - Aristotle University of Thessaloniki

Digital Timer Enhancement -  This simple circuit automatically activates or deactivates an electronic device at the time of alarm preset in a clock.  When the alarm rings, the tone burst generated at the terminal of...__ Electronics Projects for You

Digital Timer for Less than $20 -  Just "nick" the timer from an old microwave oven and fit it into a case.  The resulting timer has lots of uses.__ SiliconChip

Digital timer has independent on/off period -  03/28/96 EDN Design Ideas:  You can easily implement a long-interval digital timer using the popular 4060 oscillator-divider IC .  However, in repetitive-timer applications, this IC produces equal on and off times.  The circuit in Figure 1 allows you to set different on and off times; the state of the timer’s Q14 output automatically selects one of two independent RC time constants __ Circuit Design by Sanjay R Chendvankar, Tata Institute of Fundamental Research, Bombay, India

Digital Timer with 7-Segment Display & Pushbuttons -  The original version of xTimer used MAX7219 for driving 7-segment.  This new design uses a cheap CMOS shift register, 4094 for LED interface.  Each 4094 drives a 0.5" 7-segment without the need of limiting resistor.  The left-hand LED is timer function with buzzer alarm output.  The right-hand is for clock display.   __ Designed by Wichit Sirichote

Digithermo 0-100.0 °C -  Build your own a laboratory instrument for measuring time and temperature.  The DigiThermo demonstrates the use of 'C' language, a dual-slope converter, LCD interfacing, and digital filtering as well.   __ Designed by Wichit Sirichote

Dim 12V Light Bulb with 555 IC -  This light dimmer is used to dim the intensity of 12V light bulbs using the well-known 555 timer that is configured as an astable multivibrator.  The pulses from pin 3 are used to control the VMOS transistor BUZ20, BUZ72 or 10N10.  The maximum dissipated power must not exceed 40 watts.  You may use the transistor without a __ Designed by Popescu Marian

Divide a TTL Clock Signal by 1.5 -  Two inexpensive ICs  divide a TTL clock signal by 1.5.  By following the circuit with another flip/flop, you could also generate a divide by three function . . . Hobby Circuit designed by David Johnson P.E.-July, 2000

Divide By 1.5 Counter -  Two inexpensive ICs  divide a TTL clock signal by 1.5.  By following the circuit with another flip/flop, you could also generate a divide by three function. . . Circuit by David Johnson P.E.-July, 2000

Divide by N using '161s -  Here is a simple circuit for obtaining divide-by-N from '161s.  The technique will work for one, two, or more dividers to obtain the desired N value.  One counter handles N values up to 16, two counters divide by N values up to 256, etc __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Divide Frequency by N+5 -  07/11/02 EDN Design Ideas:  Digital frequency dividers usually use flip-flop stages that connect the Q pin to the D data-input pin of the following stage.  This configuration creates a binary waveform that you can feed back to the input.  You can divide any integer lower than 2N with minimal stages, where N is the number of stages __ Circuit Design by Bert Erickson, Fayetteville, NY

DIY Water Softener System -  Hard water has a high concentration of minerals, and of these calcium salts are the most troublesome.  But there is a solution coming in form of a cheap diy water softener system built with the well-known 555 IC .  Actually the price of this diy system is so low that even if this doesn’t work you won’t be upset.  The __ Designed by Popescu Marian

Dog Repellent Project -  The electronic dog repellent circuit diagram below is a high output ultrasonic transmitter which is primarily intended to act as a dog and cat repeller, which can be used individuals to act as a deterrent against some animals.  it should NOT be relied upon as a defence against aggressive dogs but it may help distract them or __ Designed by Popescu Marian

Dome light dimmer (with Delay) -  For all you guys out there that want a fading dome light (aka courtesy light aka theatre lighting) without having to pay for one, you can build your own.  I have attached the schematics and you can build it for a few bucks given that you don't have any spare components lying around otherwise it can cost you absolutely nothing.  Of course you can rip some parts from your TV, CD player, radio, etc.  , but i'm not responsible for the damage you cause this way [b:e43bc460fa]The way it works[/b:e43bc460fa] I won't bother you with technical__ 

Don't let Slows Slowdown the system -  08/17/98 EDN Design Ideas:  NOTE:     FILE
has several circuits, scroll to this one.  A combinatorial function with a propagation delay greater than the system clock period does not necessarily prevent a design from operating at frequency.  By taking advantage of arrival times or carefully using wait states, a design can give the combinatorial circuit sufficient time to settle before __ Circuit Design by Kevin Skahill, Cypress Semiconductor, San Jose, CA

Door knock Alarm with timer -  This low-cost circuit uses the piezoelectric element of a piezobuzzer as the input sensor.  The piezoelectric element plate is fixed at the centre of the door wing by using a cello tape.  Apply a small quantity of adhesive at the edges between the plate and the door.  Extend wires about 1-1.5 metres from the piezoelectric to the circuit.  __ 

Door Monitor -  counts the number of times a door is opened.  Counts up to 9 but can be easily expanded __ Contact P. Townshend - EduTek Ltd

Door Timer with Alarm -  We are in a digital era!  Now we can add some intelligence to our doors and gates without too much investments.  Just assemble this little door timer circuit built around a few cheap and simple components and link it to any door/gate as per your requirement and taste.  if the door/gate remains in open condition for a prefixed __ Designed by T.K. Hareendran

Doorbell with Counter -  This circuit uses a synthesized sound chip from Holtek, the HT-2811.  This reproduces the sound of a "ding-dong" chiming doorbell.  Additionally, the circuit includes a CMOS 4026 counter display driver IC to count your visitors __ Designed by Andy Collison

Door-Knock or Vibration Alarm -  This is a simple circuit that activates an alarm when there is a knock on the door or there are any vibrations due to movement of heavy goods or furniture.  The circuit uses readily available components.__ Electronics Projects for You

Drive 12 LEDs with One I/O Line -  4-Feb-10 EDN Design Ideas:  Use a binary counter to generate LED-lighting codes __ Circuit Design by Charaf Laissoub, Maisons Alfort, France

Driving a Bi-Coloured LED -  Some 3-leaded LEDs produce red and green.  This circuit alternately flashes a red/green bi-coloured LED__ 555-Timer

Driving a Relay -  The 555 will activate a relay.  When pins 2 and 6 are connected as an input, the chip requires only about 1uA to activate the output.  This is equivalent to a gain of about 200, 000, 000 (200 million) and represents about 4 stages of amplification via transistors__ 555-Timer

Driving White LEDs -  The 555 is capable of sinking and sourcing up to 200mA, but it gets very hot when doing this on a 12v supply.  The following circuit shows the maximum number of white LEDs that can be realistically driven from a 555 and we have limited the total current to about 130mA as each LED is designed to pass about 17mA to 22mA maximum.  A white LED drops a characteristic 3.2v to 3.6v and this means only 3 LEDs can be placed in series.  __ 555-Timer

DS: Clock/Calendar/Alarm with EEPROM-based interpreter & DS Interface (ATtiny12) -  This is the timekeeping test circuit.  it includes a one-transistor circuit to switch in the 5V power supply when present and drop back to the 3v battery the rest of the time.  That loop of blue wire-wrapping wire is a lariat used to quickly and easily pull the chip out of the socket during development without damage and without having to reach for the removal tool.   __ Designed by Dick Cappels

Dual Light PIC Switch -  This is a lamp timer capable of operating two separate relay switches.  Outputs can be in three (or restricted to two) states: OFF, delayed ON and constant ON.  Delayed ON mode is indicated by the LEDs.  The source code is easily customizable for your needs: set your desired delay time or disable constant ON state.  __ 

Dual Light Timer based on PIC -  Uses PIC 12F629 __ Designed by Peter Jakab

Dual 7-Segment Scoreboard -  a dual display that has controls to count up, down and reset.  Runs from 5-12volts __ Contact P. Townshend - EduTek Ltd

Dummy Alarm -  This project makes a superbright LED flash briefly once every 5 seconds to imitate the indicator light of a real alarm.  The circuit is designed to use very little current to prolong battery life so that it can be left on permanently.  This is a simple project, ideal for a beginner __ Designed by John Hewes

Dynamic clock provides for zero wait states -  03/27/97 EDN Design Ideas:  The clock controller in Figure 1, which you can implement in a PLD, dynamically manipulates the timing of synchronous FiFO clock and control signals to provide for zero-wait-state accesses.  These zero wait states would be otherwise impossible with a fixed clock design.  This concept __ Circuit Design by Mike Nelson, Polaris Communications Inc, Portland, OR

      <<<        This is last page of B - D

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

HOME Schematics Index Hobby Corner Dave's Circuits Electronic Resources Contact Info
Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches

 About Us   |  Advertise on DiscoverCircuits.com   |   Report Broken Links  |    Link to DiscoverCircuits.com  |    Privacy Policy

Copyright  January, 1998 - January, 2018     David A. Johnson & Associates.  All Rights reserved. 

 Linking is ALLOWED but COPYING any content or graphics to your web site is EXPRESSLY PROHIBITED.