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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 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 806-368-7747


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

E555 Basic Monostable -  Use of the ubiquitous 555 timer in monostable mode.   __ Designed by Andy Collison

NE555 Low Voltage Battery Disconnect -  A simple automatic circuit that will disconnect a battery before it can be discharged too low and be in danger of cell damage.  Very useful for remote radio sites and to protect any battery used for emergency backup purposes.   __ Designed by Burton Lang

NE555 Timer Sparks Low-Cost Voltage-To-Frequency Converter -  02/21/08  EDN Design Ideas:  The combination of an NE555 timer and a Miller integrator yields a voltage-to-frequency converter that costs less than 50 cents __ Circuit Design by Gyula Diószegi and János Nagy, Divelex Ltd, Budapest, Hungary

Negative Voltage -  A negative supply can be produced by a "Charge-Pump" circuit created with a 555, diodes and capacitors as shown in the following circuit.  The output will deliver about 50mA.  __ 555-Timer

Network Lead Tester -  This was designed for confirming the continuity and correct wiring of computer network leads, but it can be adapted to check any lead with up to 8 wires by using appropriate connectors.   __ Designed by John Hewes

Night Lamp with Alarm -  This circuit automatically turns on a night lamp when bedroom light is switched off.  The lamp remains ‘on’ until the light sensor senses daylight in the morning.  A super-bright white LED is used as the night lamp.  it gives bright and cool light in the room.  When the sensor detects the daylight in the morning, a melodious __ Designed by Popescu Marian

Nixie-Clock using Neon Lamps to form Logic Gates -  The above shows my home-built digital clock.  it uses Nixie-tubes for readout.  in contrast to most other nixie-clocks being built these days, my clock does not use any transistor or IC for driving the tubes.  instead, the driving logic is built from neon lamps, together with resistors, capacitors and silicon diodes. __  Contact:  pa3fwm @ amsat.org

Nixie-Tube Clock -  This is a my nixie-tube clock built 8 years ago.   __ Designed by The Electronic Lives Manufacturing-presented Chan

Novel PICAXE LED Chaser Clock -  it's got hands to indicate hours, minutes and seconds, plus chaser LEDs that stop and freeze at the seconds hand__ SiliconChip

Off-the-shelf watchdog serves in a pinch -  01/07/99 EDN Design Ideas:  The performance of the watchdog circuit in Figure 1 may not match that of a dedicated watchdog circuit, but this circuit is heLPFul when the only watchdog in the lab doesn’t meet your design’s temperature requirement and when you are in a hurry to finish a prototype   Page includes several designs.  Scroll to find this one __ Circuit Design by Giovanni Romeo, Istituto Nazionale di Geofisica, Roma, Italy

Old-Dog 555 Learns Six New Trick -  05/11/95 EDN Design Ideas:  The circuits in Fig 1 invert the ubiquitous 555 timer's operation.  The circuits' output polarities are the inverse of conventional 555 timers'.  The circuits' output duty cycle is exactly 50%.  Further, you have a choice of open-collector or totem-pole output-or both.  And you can feed the timing capacitor from a negative current source referenced to the circuit's common. __ Circuit Design by James Keith, IMD Fincor Electronics Division, York, PA

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

One Hour Timer -  A simple battery operated one hour timer device with an audible warning.  May be used as a parking meter timer.   __ Designed by Andy Collison

One second Audible Clock -  Accurate, finger-operated portable unit; 3 - 12V Battery supply __ Contact Flavio Dellepiane, fladello @ tin.it

One Second Time Base from Crystal Oscillator -  The schematic above illustrates dividing a crystal oscillator signal by the crystal frequency to obtain an accurate (0.01%) 1 second time base.  Two cascaded 12 stage counters (CD4040) form a 24 stage binary counter and the appropriate bits are gated together to produce the desired division.  Using a crystal of some even multiple of 2 is desirable so that one stage of the counter automatically toggles every second which eliminates the need for the NAND gate and reset circuitry, however the circuit below illustrates using a crystal which is not an even multiple of 2 and so requires additional __ Designed by Bill Bowden

One Second Timebase -  Here are the instructions how to get one-second (1hz) pulses from a broken quartz clock.  This is a precision timebase generator that can be used in any project that needs exactly one-second pulses. (6/11/2006) Updated!  __ Designed by Jose Pino

One-Shot Timer for Energy Saving Lighting -  Note that the circuit is coupled directly to AC mains using the existing system in the building.  A switch is used to start the timing and light one or more bulbs.  The relay is powered from 12V and its contacts must outstand up to 1kW at 220V.   __ Designed by Popescu Marian

On-Time Programmable Pulsed Solenoid Driver -  The LTC6993 is a monostable multivibrator (also known as a one-shot pulse generator) with a programmable pulse width of 1μs to 33.6 seconds.  The LTC6993 is part of the TimerBlox family of versatile silicon timing devices.  A single resistor, RSET, programs an internal master oscillator frequency, setting the LTC6993’s__ Linear Technology/Analog Devices App Note, Oct 26th 2010

Op Amp Triangle-Wave Generator & SPICE simulation files -  This signal generator gives you two waveforms for the price of one: a triangle-wave and a square-wave. What is the central component of this circuit? The integrator capacitor Ci__ 

Op-amp Astable Timer -  An astable timing circuit made from the ubiquitous 741 op-amp.   __ Designed by Andy Collison

Original Two-wire Game Show Time -  Several Game Show timers included, scroll to find this one.  The game show timer determines which contestant presses their button first by lighting a lamp and ringing a bell and the slower  contestants are locked out.  The circuit is convenient in that only two wires are needed to interconnect the stations and the wires may all go back to the base unit or they may be "daisy-chained" between stations.  There is no electronic limit on the number of stations.  The circuit uses a 24 volt power source and 12 volt lamps when built as shown but the experienced experimenter may scale these voltages along with the zener voltages if desired.  if the SCR triggers when the power is applied or when the reset button is pressed, add a 0.1uF capacitor from anode to cathode. (A sudden increase in voltage across some SCRs can trigger them, especially if the gate impedance is high.)  __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

Ornamental Flashing LEDs -  This circuit can flash three sets of LEDs with different levels of Flashing.  it can be used as Ornamental displays.  The circuit uses a simple Astable multivibrator built around the popular timer IC NE555.  Resistors R1, R2 and capacitor C1 determines the output frequency.  When the output becomes high, Red LEDs lights first.  When __ Designed by D Mohankumar

Oscilloscope CRT Clock -  Apparently i'm in the shameful habit of making clocks in my spare time.  First it was the Weston voltmeter clock, and then "Nixie 1, " a single-digit Nixie clock.  Since soon after finishing the latter, I'vebeen daydreaming about making a clock out of an electrostatic deflection CRT—the kind of thing you find in an oscilloscope.  Given that I'vejust come across some free time in the form of Christmas vacation 2005, I decided to make one of my own __ Designed by © 2007 Riad S. Wahby

Overheat Detector Alarm Switch -  At the heart of this overhead detector (fire alarm) circuit is a precision integrated temperature sensor type LM35 (IC 1) , which provides an accurately linear and directly proportional output in mV, over the zero to +155 degrees C temperature range.  This can be used as part of fire smoke detectors but do not use it as a home __ Designed by Popescu Marian

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

 


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