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Timers and Counters Circuits

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Last Updated: November 22, 2021 02:42 PM

Circuits Designed by Dave Johnson, P.E. :

Call-for-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 Dave Johnson P.E.-September, 2005

Camera Shutter Time Measurement -  A while back I received an email from someone who needed a simple way to measure the speed of a photographic camera.  I thought about this and suggested the method below.  It relies on an oscilloscope and a cheap photodiode to measure the speed . . . Hobby Circuit designed by Dave Johnson P.E.-August, 2011

Chicken Coop Door Opener with Timer -  I received an email from a guy in Australia who was trying to build a chicken coop system.  He was planning on using a conventional garage door mechanism to open and close the 6 doors to the coop.  The commercial door opener opened and closed the doors with a single pushbutton.  He wanted to install a standard 220vac powered timer so he could open the doors in the morning and close them at night. . . Circuit by Dave Johnson P.E.-March, 2013

Circuit Forms 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 Dave Johnson P.E.-July, 2000

Closet Light with Automatic 3-Minute Timeout -  The circuit below is powered by three 1.5v alkaline AA cells.  With a finger tap to the pushbutton trigger switch, a cluster of 6 wide angle white LEDs is turned on.  The lights remain on for about 3 minutes, then will turn off.  The circuit’s standby current is only a few microamps.  A set of fresh batteries should last at least 200 light applications.  The circuit uses a Schmitt trigger inverter and two transistors.  When the pushbutton switch S1 is pressed, the 10uF capacitor C1 is discharged. . . Circuit by David A. Johnson P.E.-November, 2010

Computer, Long Period, 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 . . . Hobby Circuit designed by Dave Johnson P.E.-January, 1998

Count Cars with Laser -  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 . . . Hobby Circuit designed by David A. Johnson P.E.-January, 2007

Darkroom Camera Shutter Timer -  This circuit was designed to control a film exposure shutter for a darkroom.  It has 8 time steps ranging from 0.35 seconds to 4 seconds.  It is activated by a foot switch and draws power from an external 12-volt DC supply. . . Circuit by David Johnson P.E.-June, 2000

Digital Counter using Pedometer -  There are many occasions when you may want to count something electronically.  Perhaps it is car traffic on a street or items moving down an assembly line.  It might be the number of times a machine is activated or maybe you want to count the number of . . . Hobby Circuit designed by David Johnson P.E.-August, 2008

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

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
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Links to electronic circuits, electronic schematics and designs for engineers, hobbyists, students & inventors:

Backup Clock Controller Checks Time Setting -  01/05/95 EDN Design Ideas:  The simple, inexpensive circuit in Fig 1 provide as backup power to a clock IC during outages.  The circuit also determines whether the outage caused any loss in the time setting.  C1provide as the backup power, and the µC's ADC reads the time after the outage Design by David W Jordan, RL Drake Co, Franklin, OH

Balanced Frequency Converter (Suitable for Frequencies up to 50kHz) -  This circuit takes advantage of aliasing that occurs in any time sampled system.  The output signal frequency is the difference in frequency between the input signal and the switch sampling rate.  A 24KHz input signal sampled at 25KHz will be converted to a 1KHz output signal.  in addition by using the LTC1992 fully differential __ Linear Technology/Analog Devices App Note, Mar 16th 2010

BasIC 555 Monostable -  Use of the ubiquitous 555 timer in monostable mode.   __ Designed by Andy Collison

Basic IC MonoStable Multivibrator -  Schematic only, no circuit description included.   __ Designed by Tony van Roon  VA3AVR

Bedside Lamp Timer -  30 minutes operation; Blinking LED signals 6 last minutes before turn-off __ Contact Flavio Dellepiane, fladello @ tin.it

Bicycle Anti-Theft Alarm -  I hate to suggest the specific application ‘bicycle’ because it may be use to protect many items from theft.  This anti-theft alarm project is built around the inexpensive Measurement Specialties DT piezo film sensor.  Every now and then everything seems to work out perfectly as in the Yin and Yang of the cosmos, and __ Designed by Jim Keith

Big LED Clock -  The circuit uses a serial-in-parallel out shift register, 74HC595 for receiving serial data from uController board.  See example of U5 in the schematic, SER is for data input, SRCLK is shift clock and RCLK is Latch clock.  Each data bit is shifted into the register on rising edge of the shift clock.  When all data bits are shifted into the 8-bit register, the rising edge of RCLK will clock the data to be latched at each output bit, i.e.  QA - QH. __ Designed by Wichit Sirichote

Big-Digit 12/24 Hour Clock -  it's large, it's bright, it's very accurate and can be used in either 12 or 24-hour mode.  A PIC  processor powers the works.__ SiliconChip

Bike Turning Signal -  This circuit can be used to indicate left and right turn on a motor-bike.  Two identical circuits will be needed, one for left and one for right.  __ 555-Timer

Billiards Ball Counter -  21-Feb-14 -Design News:   I wanted to play a little pool with my brother, but to play call shot, you really need a set of counters to keep track of the number of each of your successes.  My facility has no resources to do this -- neither manual counters nor the familiar beadwork located somewhere above the table.  Electronic __  Gadget Freak-Case #251

Binary clock -  This clock displays the time in binary using discrete LEDs.  The use of Flowcode [1] makes it very easy to program the PIC  controller in this project.  The circuit is very simple.  must register on this site __ Designed by Hans Summers

Binary clock using LED matrix to display a binary clock with 6 digits of 4 binary bits each -  Timing and oscillator circuit diagrams / circuit schematics __ Designed by John Main

Binary Coded Decimal (BCD) Clock -  The clock circuit above uses seven ICs  and 19 LEDs to indicate binary coded decimal time.  The LEDs can be arranged (as shown in example above) so that each horizontal group of 3 or 4 LEDs represents a decimal digit between 0 and 9 and each individual LED represents a single bit or (binary digit) of the value.  Binary digits __ Designed by Bill Bowden

Binary counter uses LSB feedforward -  08/05/99 EDN Design Ideas:  A typical synchronous binary counter contains a series of flip-flops, each of which changes state when all least significant bits (LSBs]are logic 1.  This repeated AND function is  Achilles' heel of  binary counter.  A designer has two choices  Use a ripple AND function (Figure 1) , or a parallel AND function (Figure 2] Design by Robert Carter, Siemens PLC, Congleton, Cheshire, UK

Bipolar Input (AC) V/F Converter -  input integrator uses precision full-wave rectifier for an absolute-value integration charge.  Since not ground referenced, the integration ramp is sensed by a diff amp structure that drives the V/F output comparator.  A simple comparison forms a sign bit.  __ Linear Technology/Analog Devices App Note, Jun 21, 2011

Bi-Polar LED Driver -  Some 2-leaded LEDs produce red and green.  These are called Bi-polar LEDs.  This circuit alternately flashes a red/green bi-polar LED__ 555-Timer

Bistable Switch -  This circuit shows how to implement a simple bistable (On/Off) switch.  You can also do this with a Schmitt trigger gate or inverter.  Just set R1 and R2 to bias  input to  center point of  Schmitt trigger’s hysteresis.   __ Designed by Andrew R. Morris

Blinking Arrow -  17 LEDs in four groups bar-mode sequence.  Suitable for shop-windows animation etc __ Contact Flavio Dellepiane, fladello @ tin.it

Bob Blick's Propeller Clock -  A motor spins the "propeller", and a small microprocessor keeps track of time and changes the pattern on seven LEDs with exact timing to simulate a 7 by 30 array of LEDs.  it is an illusion, but it works nicely.   __ Designed by Boblick

Bootstrapped Timer -  This circuit demonstrates how to use bootstrapping to seriously boost output power of timer.  The LC555 can only put out about 50mA as it is.  This circuit can put out at least 200mA and goes torail as well.  The LM555 timer puts out 300mA max, but does __ Designed by Andrew R. Morris

Boxing Timer -  a student needed a timer that counted down one minute.  This does exactly that __ Contact P. Townshend - EduTek Ltd

Build a 6-Digit Nixie Clock, Pt.1 -  We have been wanting to produce this Nixie Clock project for a long time and now it has finally come to fruition.  it has the warm, facsinating glow of Nixie tubes with their hypnotic counting action, mixed with a cool blue glow from a high-brightness LED from underneath each tube.  it makes an eye-catching display, both during the day and at night.__ SiliconChip

Build a 6-Digit Nixie Clock, Pt.2 -  Last month, we gave some of the history of Nixie tubes and described the design of the NX14 clock and its circuit.  This month, we give the assembly details and describe the optional blue LED up-lighting which we think that most constructors will definitely want, together with the attractive see-through Perspex case.__ SiliconChip

Build a Simple Circuit one-chip phototimer -  8-Jul-04 EDN Design Ideas:  Recently, I needed to automatically switch on a lamp when it became dark and keep it on for a given time.  Trying not to reinvent the wheel, I looked through what was available on the market, but I could not find an inexpensive device that satisfied the requirement.  Some products worked like a photoswitch, lighting a lamp when it becomes dark and keeping it on while it is dark—in other wor Design by Abel Raynus, Armatron International, Malden, MA

Bob Blick's Propeller Clock  -  A motor spins the "propeller", and a small microprocessor keeps track of time and changes the pattern on seven LEDs with exact timing to simulate a 7 by 30 array of LEDs.  It is an illusion, but it works nicely. __ Designed by Bob Blick

Build a synchronous clock  -  Synchronous clocks are still by far the most accurate currently available as (second-hand) consumer items. While it is certainly possible to make a quartz clock that is extremely accurate, very few manufacturers choose to do so. Because they are normally so cheap, most people would be unwilling to spend the extra to obtain guaranteed accuracy, and if such accuracy were needed, no off-the-shelf quartz clock would be good enough. __ Designed by Rod Elliott (ESP)

Build An LED Propeller Clock-  My "Propeller Clock" is a mechanically scanned LED clock with seven light emitting diodes that spin, giving the illusion of numbers floating in the air. This is the first clock I ever built. I've built a few LED signs, but they get boring because I already know the message.  [Designer: Bob Blick]

Build your own LED cube -  This month's featured Gadget Freak is provided by an old favourite of the blog, Peter Griffiths.  He shares all the details necessary to build your own 5 x 5 LED cube__ 

Building an Intel 8008 Computer Clock -  About every year I design and build a new clock.  This year’s project is a clock based on an intel 8008 first generation 8 bit microprocessor.  Because it is a fairly unique project i’m putting more effort into the documentation __ Designed by Len Bayles

Burglar Alarm System -  This burglar alarm system circuit is using a infrared proximity detector that triggers an alarm when the rays falling on its sensor are interrupted.  it is different from others burglar alarm systems because is a very simple diy project and can offer you great satisfaction.  The circuit of IR burglar alarm system comprises __ Designed by Popescu Marian

Butterworth filter has adjustable group Delay -  08/08/02  EDN Design Ideas:  The Sallen-Key realization of a 5.25-MHz, three-pole Butterworth filter has a gain of 2V/V and can drive 75Ω back-terminated coax with an overall gain of 1 (Figure 1).  Used to reconstruct component-video (Y, Pb, Pr] and RGB signals, t Design by William Stutz, Maxim Integrated Products, Sunnyvale, CA


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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