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Timers and Counters Circuits

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

 

Last Updated: November 30, 2017 02:27 PM

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:

Valentine Heart -  18 LEDs flash at three different rates and you can use these to create an eye-catching Valentine Heart for that special person!  A template for the heart shape can be downloaded.  The circuit is kept simple (and low cost) by using the 4060B IC which is a counter and oscillator (clock) in one package.  The circuit requires a 9V supply, such as a PP3 battery __ Designed by John Hewes

Variable Frequency PWM -  Schematic only, no circuits description.   __ Designed by Tony van Roon  VA3AVR

VCXO Makes Inexpensive Dual-Clock Reference -  27-Nov-03 EDN Design Ideas:  This design idea describes an inexpensive circuit to generate two extremely high-quality, crystal-clock-reference-signals, one of which is a PWM-controlled VCXO (voltage-controlled crystal oscillator] clock signal (Figure 1). __ Circuit Design by Said Jackson, Equator Technologies Inc, Campbell, CA

Versatile CMOS /TTL Logic & Clock Probe -  For fault diagnosis of any logic circuit, you need a probe that can test the logic level or existence of clock activity.  The circuit shown here can be used to test...__ Electronics Projects for You

Versatile Multi-Mode Timer -  Versatile timer is based on an Atmel microcontroller and has seven different operating modes.__ SiliconChip

Versatile Object Counter -  Object counters are extensively used in industries.  Normally, these are made of expensive microcontrollers or processors.  For small-scale industries, this means a lot of cost.  Here is a simple circuit that...__ Electronics Projects for You

Versatile Special Function Timer -  This automatic timer has a wide range of applications whereby a timing cycle is initiated in response to a trigger signal.  There are quite a few uses for it in a car or you could use it on a model railway layout, in a home security system or whatever.__ SiliconChip

Versatile Timer IC -  an 8-pin pic generating hourly/daily pulses, saves lots of circuitry - example circuits also __ Contact P. Townshend - EduTek Ltd

VersaTimer/Switch with Self-Latching Relay -  Use it as a micropower switch, programmable timer and/or 12V battery protector__ SiliconChip

VFD (vacuum flourescent display) clock -  This is my fifth retro display clock (others: 1, 2, 3, 4) , but the first based on a vacuum fluorescent display.  Let's get right down to it.   __ Designed by © 2007 Riad S. Wahby

Video Clock Superimposer using PIC16C711 -  As a followup to my VCR Pong project, here is a gadget that is actually useful in the Real World!  it superimposes the time of day, in "HH MM SS" format, in the bottom right-hand corner of an existing video signal.  My friend Scott uses it with his home security system__ 

Visitors Counter -  Presented here is a simple counter that counts the number of visitors entering or exiting an auditorium or any other place where you have installed this circuit at the gates.  On...__ Electronics Projects for You

Voltage Controlled Oscillator with 16:1 Frequency Range -  The LTC6990 is a precision silicon oscillator with a programmable frequency range of 488Hz to 2MHz.  it can be used as a fixed-frequency or voltage-controlled oscillator (VCO).  The LTC6990 is part of the TimerBlox family of versatile silicon timing devices.  A single resistor, RSET, programs the LTC6990’s internal master oscillator__ Linear Technology/Analog Devices App Note, Jun 16th 2010

Voltage Controlled Switch using 555 -  in this circuit the 555 timer is used in a novel way, as a voltage controlled switch.   __ Designed by Miroslav Adzic

Voltage Doubler -  A voltage higher than the supply can be created 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

Voltage Inverter using 555 Timer -  Simple and inexpensive circuit can produce a dual (positive and negative) voltage from a single supply input, extremely useful for powering OpAmp and other circuits that require a dual voltage from a single battery.   __ Designed by Aaron Cake

Wailing Siren -  By pressing the button, the wailing sound increases.  Releasing the button decreases the wailing.  The circuit automatically turns off after about 30 seconds.  __ 555-Timer

Watch Man Watcher -  Here is a circuit that can be used in offices, stores, warehouses, etc during night to check whether the watchman of your establishment is on duty.  For operation, it uses an...__ Electronics Projects for You

Watch-Dog for Telephones -  Most of the telephone security devices available in market are simple but quite expensive.  These devices provide blinking or beeping type line-tap misuse indications.  Quite often they do not offer guaranteed...__ Electronics Projects for You

Watch-Dog for Telephones -  Most of the telephone security devices available in market are simple but quite expensive.  These devices provide blinking or beeping type line-tap/misuse indications.  Quite often they do not offer guaranteed protection against unauthor-ised operation.  A very simple and uni- que circuit of a telephone watch-dog to safeguard subscriber telephone lines against any fraud is described here.  This little circuit keeps continuous watch over the telephone lines and sounds an alarm in case of any misuse.  in addition it transmits a loud tone through the telephone lines to prevent further misuse.  __ 

Watchdog protects against loss of battery charger's control signals -  21-Jul-05 EDN Design Ideas:  Hardware circuit keeps software-based charging within limits __ Circuit Design by Andy Fewster, Maxim Integrated Products Inc, Hampshire, UK

Watchdog reset catcher aids embedded system Debugging  -  11/19/98 EDN Design Ideas:  NOTE: Multiple circuits included.  Scroll to find this one.   A simple "junk-box" circuit uses a 4013  CMOS flip-flop and a handful of passive components to determine whether random resets are the result of a blown stack or the result of the watchdog-reset circuit tripping (Figure 1).  You can also use this circuit to "grab" and hold __ Circuit Design by Scott Newell, PCSI, Fort Smith, AR

Watchdog Time-Out Is Independent Of Reset -  09/01/95 EDN Design Ideas:  Many embedded systems use µP supervisors with on-chip watchdog timers.  Some supervisors, such as the MAX691, allow you to select different watchdog and reset time-out periods, depending on how you connect pin 7 (Osc in] and pin 8 (Osc Sel].  Table 1 in the MAX691 data sheet indicates the available watchdog and reset time-out choices.  However, when you implement __ Circuit Design by Larry Buyan, Criticare Systems Inc, Waukesha, WI

Watchdog timer allows entry to test Mode -  07/19/01  EDN Design Ideas:  Manuals for microprocessor-based devices often include instructions for entering a "secret mode" in which you can test or reset the device.  These instructions typically ask you to depress and hold one or two switches for a minimum  __ Circuit Design by Greg Sutterlin and Larry Barnes, Maxim Integrated Products, Sunnyvale, CA, and Craig Gestler, Mining Safety Appliances Co, Mars, PA

Watchdog timer assumes varied roles -  02/01/01 EDN Design Ideas:  The MAX6369-74 series of pin-selectable watchdog timers are designed to superviseµP activity and indicate when a system is working improperly.  During normal operation, aµP should repeatedly toggle the WDI (watchdog input) before the selected watchdog-time-out period elapses to indicate that the system is properly executing code.   __ Circuit Design by Terry Millward, Maxim Integrated Products, Lambourn Hungerford, UK

Watchdog Timer Assumes Varied Roles -  The following App Note demonstrates alternative uses for the MAX6369-MAX6374 family of pinselectable watchdog timers.  Alternative uses include a power saving power-on LED indicator circuit, load connect/disconnect circuit and push-button reset circuit. (582) __ 

Watchdog Timer for Robust Embedded Systems -  n a complex embedded system, a small bug may crash the whole system, or worse, put it into a dangerous operating mode.  Bugs are not the only problem.  A perfectly-designed-and-tested device on which a perfect code executes can still fail.  A watchdog timer (WDT) is a safety mechanism that brings the system back to life when it crashes.  For this reason, it must be well-designed and implemented for robust embedded system development.__ Pratyush Gehlot

Watchdog Timer Reboots PC's -  06/05/97 EDN Design Ideas:  When you use a PC to control a process or collect data, it's often desirable to have a watchdog timer reboot the computer if it runs astray.  The circuit in Figure 1 uses a PIC 16C84.   __ Circuit Design by Charles Hamilton, Burr-Brown Corp, Tucson, AZ

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

Watchdog uses AC triggering -  08/16/01 EDN Design Ideas:  A dc-triggered reset of a watchdog circuit is prone to failure.  if the watchdog program hangs up, then the reset signal becomes activated continuously, and the microprocessor has no way to escape the situation.  We found that a simple solution uses an ac trigger to reset the watchdog circuit (Figure 1)  __ Circuit Design by Shyam Tiwari, Sensors Technology Private Ltd, Gwalior, India

Watchdog uses Leftover Gates -  08/01/96 EDN Design Ideas:  The reset and µP-controlled watchdog circuit in Figure 1 a makes good use of some unused inverter gates in IC 1.  The design is extremely simple.  The circuit is a continuously running oscillator with programmable high- and low-level pulse widths that have additional intervention-control input from the µP.  Because the circuit is a continuous running oscillator, the circuit generates __ Circuit Design by Shyam Sunder Tiwari, IGCAR, Kalpakkam, India

Weekly Reminder -  This circuit reminds you of all the important tasks that are due on a specific day every week.  So be it returning your library book, switching on your favourite TV programme, ...__ Electronics Projects for You

Weston Voltmeter Clock -  This was the first clock I built, but I'vesince built a couple others, a single-digit NiXiE and a CRT clock, so the whole count-60-cycles seems like old hat at this point.  The PIC  sits there interrupting on RA4/T0CKI and dutifully keeping count of those oh-so-accurate (at least, over long periods of time) cycles coming out of the wall.   __ Designed by © 2007 Riad S. Wahby

Wide Frequency Range 555 VCO -  The 555 frequency can be varied via adjusting the voltage at pin 5.  However, the range and linearity of frequency adjustment is very limited.  This is a way to greatly improve performance using the inverted 555 timer circuit that was previously posted.555 VCO Schematic Current source Q2 is connected in the common base __ Designed by Jim Keith

Wide-swing Variable Crystal Oscillator -  Timing and oscillator circuit diagrams / circuit schematics __ Designed by Peter Parker VK3YE

Wien Bridge Oscillator with SPICE simulation -  Timing and oscillator circuit diagrams / circuit schematics__ 

Windshield Wiper Delay -  The intermittent wiper circuit shown above causes the auto's windshield wipers to wipe once every several seconds instead of constantly wiping.  The circuit may be added to older cars to provide the intermittent function or it __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

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

Xtimer V1.0 -  Easy build 4-channel timer, suitable for energy saving, simple hardware and nice firmware with c coding.  Automatic power down mode, simple settings, optional buzzer for sound alarm.   __ Designed by Wichit Sirichote

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