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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 Closer   -  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 . . . Dave Johnson, Lubbock TX (May 14, 2011)-DC Magazine - Issue 18 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:

Gag Bomb Countdown Timer -  18-Jul-14 -Design News:   I created this Hollywood movie-style gag bomb that doubles as an alarm clock and a countdown timer.  This is a fun project that you can build in a day or two.  it is made using an 8051 microcontroller.  The project can be easily done with other microcontrollers or an Arduino, or you can even hack an __  Gadget Freak-Case #259

Galloping Neons -  Here is a line powered array of blinking neons designed for continuous duty.  it would be quite dangerous to power a circuit directly from the power line so some form of isolation is needed.  Since most experimenters will not have 120 volt isolation transformers __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Game Show Timers -  Here is a really simple game show timer designed with the beginner in mind!  The power source is an ordinary 12 volt lantern battery or battery pack made up of C or D cells.  The lamps may be ordinary flashlight bulbs; the prototype uses 750 mA Krypton types (KPR112) with wires soldered directly onto the bulbs.  The control devices __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Garage Door Closer   -  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 . . . Dave Johnson, Lubbock TX (May 14, 2011)-DC Magazine - Issue 18 May 2011

Garden Timer with Remote control -  Few years ago we control the lights in the garden with a automatic-timer-switch, very nice but when the evening gets longer or shorter we had to adapt the timer each week.  in that time I came in contact with programming microprocessors so my first project was born.  The first garden timer was a simple 1 output.  The timing was controlled by the PIC  and every month I had to change the minutes.  So back to the table and design the second garden timer able to control 3 relays, left, mid and right side of the garden.  it provided also 4 modes: always off always on from dusk to dawn from dusk to timer and the timing was dedicated to a RTC DS1307.  __ 

Garden Watering Timer -  The timer circuit uses CD4000 series CMOS logic -no firmware at all.  The circuit board was cut to fit where the original circuit board in the Rain Bird Timer had been.  The barrier terminal strip was salvaged from the original circuit board (Gates and counters; no microcontroller)  __ Designed by Dick Cappels

Gas Leak Detector -  Here is a gas leak detector circuit that detects the leakage of LPG gas and alerts the user through audio-visual indications.  The circuit operates off a 9V PP3 battery.  Zener diode ZD1 is used to convert 9V into 5V DC to drive the gas sensor module.  The gas leakage circuit uses the SEN-1327 gas sensor module from RhydoLABZ.   __ Designed by Popescu Marian

Gated clock has duty-cycle control -  08/17/00 EDN Design Ideas:  The circuit in Figure 1 produces clock pulses with variable duty cycle from a gated clock.  The output of the circuit, pulse, is always 180 out of phase with the clock input.  When the delay-logic elements, IC 5 and IC 7, have the same propagation delays, the duty cycle of the circuit's output is 50%.  The circuit __ Circuit Design by Paul Kemp, University of Colorado, Colorado Springs, CO

Generating a Delayed Pulse with a Dual 555 Timer -  The circuit below illustrates generating a single positive pulse which is delayed relative to the trigger input time.  The circuit is similar to the one above but employs two stages so that both the pulse width and delay can be controlled.  When the button is depressed, the output of the first ( __ Designed by Bill Bowden

Generating Long Time Delays -  Generating long delays of several hours can be accomplished by using a low frequency oscillator and a binary counter as shown below.  A single Schmitt Trigger inverter stage (1/6 of 74HC14) is used as a squarewave oscillator to produce a low frequency of about 0.5 Hertz.  The 10K resistor in series with the input (pin 1) reduces the capacitor discharge current through __ Designed by Bill Bowden

Generating-5 Volts from a 9 Volt Battery -  This is a basic 555 squarewave oscillator used to produce a 1 Khz tone from an 8 ohm speaker.  in the circuit on the left, the speaker is isolated from the oscillator by the NPN medium power transistor which also provides more current than can be obtained directly from the 555 (limit = 200 mA).  A small capacitor is used at the transistor __ Designed by Bill Bowden

Giant nixie clock -  At the beginning of 2001 I had never heard of nixie tubes.  Then I came across Mike's Electric Stuff and saw his Nixie Clock.  Almost instantly I fell in love with nixies then I had the idea of building a nixie clock and this project was the result. __ Designed by Hans Summers

GPS Driver Module for the 6-Digit Clock, Pt 2 -  Based on the GlobalSat EM-408 GPS module, this compact GPS receiver/driver board mates with the 6-digit display described in Pt.1 to form a self-contained GPS clock.  it can also be housed separately and used to provide NMEA 0183 time and date information to a PC, via a serial port.__ SiliconChip

GPS Module for Your PC -  Link it to your PC and trace your position on and on-screen map.  There's lots of freeware and shareware to use with it as well.__ SiliconChip

GPS receiver based frequency standard -  Frequency accuracy has been a topic of special interest to many amateurs and experimenters since the early days of radio.  Until recently, the best frequency standard available to most hams was a crystal oscillator carefully adjusted to zero-beat __ Designed by Brooks Shera, W5OJM

GPS-Synchronised Clock -  Tired of resetting the time on your wall clock? This GPS circuit will convert a standard battery wall clock into a precision timekeeper that never needs to be corrected.  it will even automatically adjust for daylight saving time.__ SiliconChip

Graphical Alarm Clock -  Software: The software is written in a state machine manner.  Here are the states: (the state numbers were chosen randomly) State 1: Show the power up graphics State 2: Main time/date display State 50: Main menu State 60: Set the clock State 61: Set __ Designed by Atmel ATmega32 Part 1

Group Delay Equalizer has Gain More than One -  10/12/95 EDN Design Ideas:  For numerous applications, flat group delay (linear phase) is necessary to maintain system performance.  The common group-delay equalizer of Fig 1a has unity gain and is a popular way to equalize data filters or alias filters when phase compensation is necessary.  The alternative equalizer of Fig 1b, however, can provide a gain greater than one for systems that require additional gain (and when providing that gain elsewhere is impossible or impractical).    __ Circuit Design by Mark Weigel, Scottsdale, AZ

Hack into a stopwatch to make a phototimer -  11/03/11  EDN Design Ideas:  Two transistors create a pulse train to operate a stopwatch - The exposure tester in this Design idea   measures the on time of a light source, whether an LED, an incandescent lamp, a halogen lamp, or another source.  it can be made with an ordinary stopwatc __ Circuit Design by Ralf Kelz, Seefeld, Germany

Hacks And Mods: Incredibly Illuminated Persistence Of Vision Led Clock -  Persistence of Vision flashes LEDs during sure moments as it spins, to illustrate formulating a clock above.  The PCB blades have been spun around regulating a pc cooling air blower to create this POV clock.  The existence outcome is interjection to bright LEDs that have been synchronized with a Hall Effect sensor.  The house gets__ 

Hard Drive Clock -  Have an old hard drive that no longer works? As long as it still spins up chances are you could build a clock out of your old hard drive!  You will need some electronic knowledge, some common electronic components and a bit of patience.  The clock that is produced isnt exactly practical __ Designed by Alan Parekh

Hardware Watchdog Timer Accepts Range Of Frequencies -  08/12/10 EDN Design Ideas:  A timer removes power from a circuit should a microcontroller fail to produce pulses.    __ Circuit Design by Robert Most, Ferris State University, Big Rapids, MI

H-Bridge -  This circuit drives a motor clockwise / anticlockwise via a 10k to 100k pot.  __ 555-Timer

H-Bridge -  This circuit drives small DC motors up to about 100 watts or 5 amps or 40 volts, whichever comes first.  Using bigger parts could make it more powerful.  Using a real H-bridge IC makes sense for this size of motor, but hobbyists love to do it themselves, and I thought it was about time to show a tested H-bridge motor driver that didn't use exotic parts __ Designed by Boblick

H-Bridge with PWM -  This circuit drives a motor clockwise / anticlockwise via a pot and reduces the speed to zero when the pot is in mid-position.  The current is limited to 200mA and the voltage across the motor is less than 6v, but the circuit shows the principle of Pulse Width Modulation (providing powerful bursts of current to the motor to create a high or low RPM under load) and both forward / reverse RPM via the H-bridge arrangement.  __ 555-Timer

HC11 Controls the Stepper -  Simple circuit with 16-pin Nitron chip 68HC908, easy analog setting, source code with IC C08.  New s-record for 8-pin 68HC908QT2!  __ Designed by Ludwig Orgler-Fachingenieur Elektrotechnik

Headlights Timer -  Pushbutton activated; Very simple circuitry __ Contact Flavio Dellepiane, fladello @ tin.it

Headphone Amplifier based on 12AX7 tubes -  Audio power amplifier circuit diagrams / circuit schematics __ Designed by 2007 Riad S. Wahby

Heart-shaped Badge -  The badge consists of eight LEDs arranged in the shape of a heart.  One LED is lit at a time and this 'chases' round the shape.  it would be easy to adapt this project to create other shapes with the eight LEDs.   __ Designed by John Hewes

Hee HaW Siren -  Build the circuit and listen.  Change the resistors and capacitors to get all sorts of different results.  __ 555-Timer

High & Low Voltage Cut Off with Time Delay -  The power line fluctuations and cut-offs cause damages to electrical appliances connected to the line.  it is more serious in the case of domestic appliances like fridge and air conditioners.  if a fridge is operated on low voltage, excessive current flows through the motor, which heats up, and get damaged __ Contact IQ Technologies

High Accuracy RPM-Measurement with 68HC12 -  Schematic + code __ Designed by Ludwig Orgler-Fachingenieur Elektrotechnik

High Frequency 555 Oscillator -  360kHz is the absolute maximum as the 555 starts to malfunction with irregular bursts of pulses above this frequency.  To improve the performance of the oscillator, a 270R and 1n can be added as shown in the second circuit:__ 555-Timer

High 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

Homebrew DDS Generator (with AD9851) V2.0 -  This Mini-Project serves just to get a universal add-on so that our 'free Samples' come to life.  We use a crystal oscillator of 150 MHz (and do not use the internal multiplier) in order to increase noise performance.  The board uses a single +12V Supply, as it will use the +5V from the Arduino board.  For the crystal oscillator a separate voltage regulator is available, in order to generate different voltages necessary for different oscillator types.  The output of the AD9851 is lowpass-filtered and amplified with a THS3201 (from Texas instruments). __ Designed by Alexander C. Frank, aka Ajarn Changpuak

Homemade scope clock using a DG7 tube & a Microchip PIC16F876 -  I was lucky to purcase two used but working DG7 tubes and a transformator cheap, one from Mullard and one from Phillips.  Other CRT Cathode Ray Tube types can be used, you can even rip one from an old and maybe dead oscilloscope __ Designed by Thomas Scherrer OZ2CPU

How to Configure a Low-Power Timer/Oscillator to Operate From Higher Supply Voltages -  06/27/12  EDN Design Ideas:  Low power, low voltage CMOS timers/oscillators like the Touchstone TS3001/TS3002 are specified to operate at 1V, consuming supply currents as low as 1A.  While the TS3001/TS3002 has an operating VDD voltage range of 0.9V-1.8V, systems running from higher supply voltages can also take advantage of the low supply currents of this micropower timer, by adding a few inexpensive transistors to the operating circuit.   __ Circuit Design by Martin Tomasz

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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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