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. :
Three-Minute Closet Light -  I have a coat closet by my front door.  The thing is very dark at night and really needs some kind of illumination inside.  I could hire an electrician to install a light in the closet ceiling and then wire it to a toggle switch outside the door but that would cost me quite a bit of money. . . Circuit by Dave Johnson P.E.-December, 2011

Timer for Darkroom Camera Shutter -  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 . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

Two Transistor 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

Two-Transistor 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 . . . Hobby Circuit designed by Dave Johnson P.E.-December, 2002

Watchdog Timer set for 36 Hrs -  A watchdog timer is often used in computer systems to detect when a computer is hung up and is no longer running properly.  If it does become locked up and is not able to supply a reset pulse to the circuit within a defined time frame the timer times out a . . . Hobby Circuit designed by David Johnson P.E.-April, 2010

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:

Simple Circuit Sine Wave Oscillator including a PCB layout -  Here is a simple Sine Wave Oscillator Circuit.   __ Designed by G.L. Chemelec

Simple Circuit Timer Exploits OpAmp Bias Current -  07/21/94 EDN Design Ideas:  The simple, low-cost analog timer in Fig 1 exploits the parasitic input-bias current of op-amp IC 1.  The timer achieves long time delays even though it uses only low-value, inexpensive ceramic chip capacitors.  After all, because the input-bias current is the minimum current flow into an op amp,  __ Circuit Design by Aleksandr Belousov, Baltimore, MD

Simple Circuit Timer Remembers Your Rhythm -  01/05/95 EDN Design Ideas:  The unpretentious controller in Fig 1 remembers the interval between your pressing its start and stop buttons.  Thereafter, the controller switches the load on and off every day at the same times as you did.  You reset the controll __ Circuit Design by MS Nagaraj, ISRO Satellite Centre, Bangalore, Karnataka, India

Simple Circuit times bathroom fan -  04/27/00 EDN Design Ideas:  Forget to turn off the ceiling fan in your bathroom? install the simple timer in Figure 1 .  it's located out-of-sight in the fan unit, and you turn it on via the wall switch.  The circuit costs virtually nothing, using "junk" parts.  When ac power appears, a simple rectifier develops approximately 7V across filter capacitor C.   __ Circuit Design by Maxwell Strange, Goddard Space Flight Center, Fulton, MD

Simple Circuit WWV receiver for 10 MHz calibration signal -  Simple Direct Conversion receiver to use with a PC to calibrate a 10 MHz VCXO.   __ Designed by Steven Weber, KD1JV

Simplest 555 Oscillator -  The simplest 555 oscillator takes output pin 3 to capacitor C1 viaresistor R1.  When the circuit is turned on, C1 is uncharged and output pin 3 is HiGH.  C1 charges via R1 and when Pin 6 detects 2/3 rail voltage, output pin 3 goes LOW.  R1 now discharges capacitor__ 555-Timer

Simplified Analysis of Phase-Locked Loop Capture & Tracking Range an 1200-7 -  Application Note__ Aligent

Single Digit Scoreboard -  a compact general purpose display __ Contact P. Townshend - EduTek Ltd

Single Gate Synchronizes Clock -  10/27/94 EDN Design Ideas:  The deceptively simple circuit in Fig 1 harbors formidable power.  Consider when you have a data-clock input to your system for an existing serial data stream.  Then, your system people surprise you __ Circuit Design by Phil Harvey, Technology Integration Inc/, Bedford, MA

Single Transistor Relay Toggle Circuit -  The circuit below requires a double pole, double throw relay in conjunction with a single transistor to allow toggling the relay with a momentary push button.  One set of relay contacts is used to control the load, while the other is used to provide feedback to keep the relay activated or deactivated.  Several push buttons can be wired in parallel to allow toggling the relay from different locations. __ Designed by Bill Bowden

Single-digit Nixie clock -  A while ago I found a Burroughs B-5853 Nixie tube kicking around in the lab and decided that I should put it to good use.  Since I only had one of this size, I wanted to make a single-digit display out of it.   __ Designed by 2007 Riad S. Wahby

Siren 100dB -  This is a very loud siren and if two or more piezo's are located in a room, the burglar does not know where the sound is coming from.  __ 555-Timer

Sleep Switch Cum Wake Up Timer -  Here is a sleep-switch circuit that can be easily converted into a wake-up timer.  A dual-mode time setting makes the system versatile.  The circuit is low-cost and can function as a...__ Electronics Projects for You

Sleep Timer -  Use this sleep timer for your radio set at the bedside.  The time interval from START till shut off is determined by R and C by a formula;   t =16384RC/2.2 seconds.   For example, R=100k、 C=1.5uF(layered ceramic capacitor) gives t =1117 seconds(about 19 minutes)  __ Designed by MINOWA, Makoto  7N3WVM

Slow diodes or handy timing Devices? -  16-Sep-04 EDN Design Ideas:  Most designers consider slowness in diodes to be an imperfection or a limitation.  Why not take apositive view of the situation? After all, a zener or an avalanche diode is nothan a diode with a limited breakdown voltage, and you can view a varactor as a diode with a large and nonlinear parasitic capacitance __ Circuit Design by Louis Vlemincq, Belgacom, Evere, Belgium

Smart Cooling Fan -  A continuously running cooling fan is a big nuisance and is not very crucial in most instruments.  The 12V smart fan control presented here allows the fan to run at rates varying from once a second to once in ten seconds approximately.  in case of a battery powered instrument, this idea will save some power too!  Basically, the __ Designed by T.K. Hareendran

Smart Photoresistor Timer Needs Few Components -  3-Sep-09 EDN Design Ideas:  Smart photoresistor senses darkness and then turns off __ Circuit Design by Abel Raynus, Armatron International Inc, Malden, MA

Smooth Tone Clickless CW SideTone Generator -  This circuit is about as good as it gets for generating morse code tones.  it may be used as a code practice oscillator, a tone generator for a keyer, a sidetone oscillator for a CW transmitter or an audio Modulated CW (MCW) generator for an FM transmitter or repeater __ Designed by G. Forrest Cook

Soft-Start for Power Amps -  Although the soft start circuit can be added to any sized transformer, the winding resistance of 300VA and smaller transformers is generally sufficient to prevent a massive surge current.  Use of a soft start circuit is definitely recommended for 500VA and larger transformers __ Designed by Rod Elliott  ESP

Solar Power System Guard -  The common home solar power system, in principle consists of a roof-mounted solar panel, a charge controller and a storage battery bank plus direct or electronic inverter powered electric lighting units.  in some situations, the solar panel is mounted on a mast extended from ground and this may become an obstacle during night __ Designed by T.K. Hareendran

Solar-Powered Sensor Controls Traffic -  26-Nov-09 EDN Design Ideas:  A traffic-sensor post measures vehicle location and speed at an intersection, providing an accurate, effective, inexpensive approach to monitoring traffic flow __ Circuit Design by Larry K Baxter, Capsense, Lexington, MA

Speed Acces to P's Real-Time Clock -  06/05/98 EDN Design Ideas:  (Scroll to find this circuit) The DS5000T (Dallas Semiconductors, www.  dalsemi.  com) is an 8051-compatible processor that integrates nonvolatile memory and a real-time clock.  This module has an impressive set of functional extensio __ Circuit Design by Jerzy Chrzaszcz, Warsaw University of Technology, Warsaw, Poland

SP-L Modulator uses Single Speed Bit Clock -  08/15/97 EDN Design Ideas:  Split-level (SP-L) , or Manchester, encoding is a common modulation scheme in data transmission (Figure 1).  SP-L is popular because bit-clock extraction at the receiving end is easy, and the modulator circuit is simple to implement--simple, but not trivial, because the output of this classic circuit suffers from severe spikes during data transitions (Figure 2).  A different circuit eliminates the spiking problem (Figure 3).  This circuit resamples data after stabilization, but to do so, it needs a double-speed clock.  This need can be as annoying as having spikes.   __ Circuit Design by Massimo Garavaglia, Robecchetto con Induno, Italy

Square Wave Oscillator -  it has adjustable (and settable) frequencies from 1Hz to 100kHz and is an ideal piece of Test Equipment.  __ 555-Timer

Square wave oscillator using 555 timer chip -  This project is a piece of test equipment.  it's a square wave oscillator with 6 selectable frequencies from 1Hz to 100kHz, incrementing in decade values.  it's most useful application is as a Signal injector for radios and TV's.  A square wave is the most suitable for testing the iF (intermediate Frequency) strip as the signal will pass through the iF transformers without any attenuation, no matter what __ Designed by Collin Mitchell

State & Timing Modules for Agilent Technologies Logic Analysis Systems -  Application Note__ Aligent

Step Alarm -  This Circuit can monitor the door steps or Staircase.  When a person crosses the steps, the alarm sounds indicating the entry.  The circuit is too sensitive and operates in day light.  The circuit uses an NPN Darlington phototransistor L14F1.  it senses the intensity of light through its exposed base and passes current in the __ Designed by D Mohankumar

Step Km Counter Max -  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

Step-Km Counter -  Pedometer has a range of 9.950 meters with2-digits.  Slip it in pants pocket for walking and jogging __ Designed by RED Free Circuit Designs

Stepper Motor Controller -  The direction of rotation is determined by the FORWARD and REVERSE switches and the motor does not take any current when a switch is not pressed.  __ 555-Timer

Stop Clock with Battery Backup -  Stop clock is widely used in various fields to measure the timing of events.  Science laboratory experiments, such as measurement of discharge rate of capacitors with different resistors, acceleration due to...__ Electronics Projects for You

Stopwatch 0-60sec -  in the present article, we will describe the function of a digital stopwatch, 0 99 sec.  The function of the stopwatch, relies in the use of 4 integrated circuits, which in this case belong to National Semiconductor (http://www.  national.  com).  it is obvious that other integrated circuits can be used to achieve the same result, however in this case we have used the following parts __ Designed by Pafilis Ioannis - Aristotle University of Thessaloniki  Department of Electronics and Telecommunications

Sun tanning timer -  This timer was designed for people wanting to get tanned but at the same time wishing to avoid an excessive exposure to sunlight.  A Rotary Switch sets the timer according to six classified Photo-types (see table).  A Photo resistor extends the preset time value according to sunlight brightness (see table). __ Contact Flavio Dellepiane, fladello @ tin.it

Sun-Up Alarm -  The Sun - Up Alarm can be used to provide a audible alarm for when the sun comes up or it can be used in a dark area and detect when a light comes on.  it can also be used to detect a light beam, headlights etc.  The circuit works as follows.  The phototransistor is very sensitive to light. (Any phototransistor will work fine)  __ Designed by Randy Linscott

Super Low Distortion Variable Sine Wave Oscillator -  The LT1028 (gain of 1 stable) /LT1128 (gain of +1 stable) achieve a new standard of excellence in noise performance with 0.85nV/rtHz 1kHz noise, 1.0nV/rtHz 10Hz noise.  This ultralow noise is combined with excellent high speed specifications (gain-bandwidth product is 75MHz for LT1028, 20MHz for LT1128) , distortion-free __ Linear Technology/Analog Devices App Note, Jun 21, 2011

Super Simple Circuit Counter -  Super Simple Counter The freebie metal detector I previously designed for [url=http://www.  thomasscarborough.  blogspot.  com/]this blog[/url] is by far my most popular post.  So here is another circuit I designed today.  Counters must be among the more sought-after electronic circuits.  However, even the simplest of them are complex.  This provides a "super simple" solution, to count from 0 to 43, 200 on a quartz clock face (60 seconds 60 minutes 12 hours).  it would be capable e.  g.  of counting attendance at most major public events.  Almost any cheap analogue quartz clock is used for the__ 

Super VXO -  The Super VXO uses two X-tals of the identical nominal frequency in parallel instead of a single X-tal of a conventional VXO.  Nothing else is special.  it can pull considerablly more frequencies than the conventional one.  About 40kHz for a pair of 10.15MHz X-tals, and 90kHz for 13MHz, according to my experiences.   __ Designed by MINOWA, Makoto  7N3WVM

Swiss Railroad Clock -  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

Switch Debounce -  The output goes HiGH for 100mS when the switch is pressed.  __ 555-Timer

Switch Debouncer -  This circuit will remove the transient spikes and contact bounces from a non-latching push button switch.   __ Designed by Andy Collison

Synchronized Timing Generators  -  Circuit ideas for Designers App Note__ Advanced Linear Devices, Inc

System implements digital clock Modulation -  10/28/04  EDN Design Ideas:  in spread-spectrum and direct-sequence receivers, it's often necessary to change the frequency of the clock oscillator, and thus the spreading-code clock, to lock the receiver's reference pseudorandom-noise code to the incoming cod __ Circuit Design by Dan Doberstein, DKD Instruments, Nipomo, CA

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

      <<<         This is the last page of M-S

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.