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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. :
2 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 Johnson P.E.-December, 2002

3 Minute LED Closet Light -  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 . . . Hobby Circuit designed by David Johnson P.E.-November, 2010

36-Hour Watchdog Timer -  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. . . Circuit by David Johnson P.E.-April, 2010

3-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 David Johnson P.E.-December, 2011

3-Minute Closet Light #2 -  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 Johnson P.E.-November, 2010

15 Minute Timer Does Not Time Out   -  The best solution would be to replace the 555 timer circuit with a digital timer, which uses an oscillator and a multi-stage counter to form at long time delay.  The cost would be minimal and since no large capacitor would be needed, the circuit would not take up much more board space.  The lesson here is that a 555 timer should never be used for times beyond about 3 minutes or so. . . . Dave Johnson, Lubbock TX-DC Magazines - 2nd Q 2012

555 Timer Forms Simple Circuit PWM Motor Controller -  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. . . Circuit by Dave Johnson P.E.-February, 2007

60hz Clock Generator is Line Powered -  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 . . . Hobby Circuit designed by Dave Johnson P.E.-February, 1999

Accurate One Shot Pulse Generator -  This timer circuit draws only 3ua of current, and can be powered by DC supplies ranging from 3v to 15v.  The circuit produces accurate pulses whose time can easily be adjusted, based on the R1 x C1 time constant.  The time should not change,. . . Circuit by David Johnson P.E.-September, 2010

Automatic Timeout included with this On/Off Flip/flop Circuit -  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 . . . Hobby Circuit designed by Dave Johnson P.E.-May, 2012

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:

"Do Not Disturb" Telephone Timer -  it takes your phone off the hook and automatically hangs up again after a preset time.  A LED indicates when the phone is off the hook.__ SiliconChip

0 to 10 Volt Control for RC Servos -  This circuit takes standard 0-10V control voltage (for example from analogue light controlling desk) and outputs a standard 1-2 ms RC servo motors control pulse.   __ Designed by Tomi Engdahl

0.01% Voltage to Frequency Converter -  The LTC6943 is a monolithic, charge-balanced, dual switched capacitor instrumentation building block.  A pair of switches alternately connects an external capacitor to an input voltage and then connects the charged capacitor across an output port.  The internal switches have a break-before-make action.  An internal clock is provided__ Linear Technology/Analog Devices App Note, Mar 31, 2010

1 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

1 kHz Quadrature Oscillator -  Schematic only __ Designed by va3iul

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

1 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 __ Designed by Bill Bowden

1 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

10MHz GPS disciplined frequency standard -  This is the support page for the GPSDO described in the RSGB magazine RadCom for March 2008.  As this has become one of those never-ending projects, I have decided to start a web-page dedicated to this project and GPSDOs in general __ Designed by EI9GQ homebrew radio

12 sec to 90 Minute Time Relay -  Schematic and notes only, no circuit description provided.   __ Designed by Tony van Roon  VA3AVR

12V Digital Timer using 240v Timer Module -  240V timers are very cheap these days.12V timers are not so cheap.  So why not use the "innards" out of a 240V timer and make a very flexible 12V timer?__ SiliconChip

12V 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

12v to 240v Inverter -  This circuit will produce 240v at 50Hz.  The wattage will depend on the driver transistors and transformer.   __ 555-Timer

13 GHz Frequency Counter Prescaler -  Here is a fairly simple "divide-by-1000" circuit which was first designed by Zeljko Bozic, S52ZB, in a 2006 issue of VHF Communications Magazine.  The idea of this project is to extend the range of older (and cheaper) frequency counters.  You can often find 100 MHz frequency counters for as little as $20 at hamfests or eBay, and this simple circuit will extend their range up to at least 13 GHz.  This version is based around a Hittite HMC363 divide-by-8 prescaler, a Fujitsu MB506 divide-by-64 prescaler, and a "divide-by-1.953125" circuit using standard digital logic.  The Hittite HMC363 front-end prescaler is good up to 13 GHz or so, and will do 15 GHz if you increase the input RF power a bit and minimize the prescaler's exposure time.  __ Green Bay Professional Packet Radio

1-3 minute timer -  Using this circuit you can switch on an appliance for a desired time.  The circuit provides selectable time settings of 1, 2, 5, 1, __ 

1-30 Minute Timer -  Using this circuit you can switch on an appliance for a desired time.  The circuit provides selectable time settings of 1, 2, 5, 10, 15 and 30 minutes, and can be used for domestic as well as industrial applications.__  S.C. DWIVEDI

13uA, 0kHz to 10kHz Voltage to Frequency Converter -  This circuit converts a 0V to 2.5V input signal to a 0kHz to 10kHz output frequency.  The supply current of the circuit is only 6.2uA quiescent and 13.3 uA at f=10kHz.  The linearity of the circuit is +/-0.03%.  PSRR is 10ppm/V and temperature drift is 250ppm/C.  __ Linear Technology/Analog Devices App Note, Mar 30th 2010

15 Minute Timer Does Not Time Out   -  The best solution would be to replace the 555 timer circuit with a digital timer, which uses an oscillator and a multi-stage counter to form at long time delay.  The cost would be minimal and since no large capacitor would be needed, the circuit would not take up much more board space.  The lesson here is that a 555 timer should never be used for times beyond about 3 minutes or so. . . . Dave Johnson, Lubbock TX-DC Magazines - 2nd Q 2012

1-90 Bingo Number Generator -  a neat little counter counting from 1 to 90 (not zero) with the aid of a few gates __ Contact P. Townshend - EduTek Ltd

1-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

1hz Precision Clock Timer -  This timer makes an LED flash once every second along with a beep.  The timing circuit uses a quartz crystal available in digital watches or clocks which generates precise frequency of...__ Electronics Projects for You

1Hz to 100MHz Voltage to Frequency Converter Has 160dB Dynamic Range, Runs from 5V Supply -  This circuit achieves a wider dynamic range and higher output frequency than any commercially available voltage to frequency (V→F) converter.  its 100MHz full scale output (10% over range to 110MHz is provided) is at least ten times faster than available units.  The circuit’s 160dB dynamic range (8 decades) allows continuous __ Linear Technology/Analog Devices App Note, Mar 25th 2010

1Hz to 10kHz Voltage to Frequency Converter -  JFET inputs with antI phase-reversal circuitry allow the LTC1055/56 to be used as a precision, ultra-high impedance comparator.  The precision provides for very high linearity of the V/F generation while the high speed allows a large frequency range of operation.  __ Linear Technology/Analog Devices App Note, Jun 21, 2011

1KHz Sinewave Generator -  Simple circuitry, low distortion, battery operated -- Variable, low impedance output up to 1V RMS __ Contact IQ Technologies

1MHz Pulse Width Modulator -  This circuit highlights the use of the LTC6992 as a 1MHz Pulse Width Modulator (PWM) ; converting an analog input into a PWM output.  The LTC6992 is part of the TimerBlox family of versatile silicon timing devices and provides an easy-to-use analog voltage-controlled PWM capability.  To program the master oscillator frequency__ Linear Technology/Analog Devices App Note, Jun 16th 2010

1MV Offset Clock-Tunable MonolithIC 5-Pole Lowpass Filter -  DN67 Design Notes__ Linear Technology/Analog Devices

1ppm Settling Time Measurement for a Monolithic 18-Bit DAC -  Linear Technology AN120 __ Designed by Jim Williams - Mar 10th, 2010

1-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

2 Nanosecond, .1% Resolution Settling Time Measurement for Wideband Amplifiers -  Linear Technology AN128 __ Designed by Jim Williams - Aug 16th, 2010

2 Transistor Atomic Frequency Standard -  Pretty ambitious title, wouldn't you say? Well, follow the reasoning: if you lower the voltage on the two-transistor flasher to 1.5 volts, the loop gain drops too low for sustained flashing. (See the circuit below.) But, the circuit is highly regenerative and only needs a very tiny push to get it going.  By adding a short wire, only a few inches, to the PNP base, the circuit will be triggered into oscillation by the AC electric field from the electrical power (50 or 60 Hz in most places)  __  Contact:  Charles Wenzel of Wenzel Associates, Inc.

2 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 Johnson P.E.-December, 2002

2.5 GHz Frequency counter -  This project describes a very powerful frequency counter.  Very simple construction which everyone can build.6 LED display will present the frequency with 1kHz resolution and RS232 communication to computer is available as option.  The software has also been implemented with some smart functions, for calculating frequencies in receivers where iF is 455kHz or 10.7MHz.  I present schematic, PCB, components and window software.  __ 

2.8-GHz prescaler keeps cost down -  07/20/00  Published in EDN    The prescaler in Figure 1 inexpensively extends the range of a frequency counter by dividing the input signal’s frequency by a factor of 1000.  The guaranteed input-frequency range.    __ Circuit Design by Neil Eaton, Emsys Engineering, Peterborough, ON, Canada

220V Solid State Flashing Lamp with 555 -  This 220V mains operated solid state flashing lamp circuit uses a 555 timer IC to control the ON and OFF times of a TRIAC which controls power to the load.  The power supply for the IC is obtained by half wave rectifier (D1) , a stabilizer circuit (D2 and R1) and filter capacitor C1.  The lamp stays ON for about 1 second and OFF __ Designed by Popescu Marian

230V Blinking LED -  This design can be of some interest for those wanting striking light signs, as it can drive up to three 230V lamp strings in three operating modes.  The 15V dc supply is obtained from a nominal 230/24V center tapped ac transformer (T1) and a full wave rectifier __ Contact Flavio Dellepiane, fladello @ tin.it

24 Hour Clock 2 -  an example of using gates to "trap" binary values on counters with positive edge clocks __ Contact P. Townshend - EduTek Ltd

24 Hour Timer -  These two circuits are multi-range timers offering periods of up to 24 hours and beyond.  Both are essentially the same.  The main difference is that when the time runs out, Version 1 energizes the relay and Version 2 de-energizes it.  The first uses less power while the timer is running; and the second uses less power after the timer stops.  Pick the one that best suits your application.   __ Designed by Ron J.

24 Hr Timer -  a timer that will switch on for 12/24 hours - once only or repeat - can be modified for up to 2 weeks!  __ Contact P. Townshend - EduTek Ltd

24 Second Shot Clock -  This is a circuit intended to be used in basketball shot clock __ Designed by Milardo de Guzman

24 Watt Class a Amplifier -  A 24 Watt Class A Amplifier made from discrete semiconductors, built and tested by Marc Klynhans from South Africa.   __ Designed by Marc Klynhans

24" Wall Clock -  Sometime ago a friend challenged us to build a 6 foot digital clock - just like the alarm clock next to your bed.  Well, because of scaling issues, 6 foot was a bit too expensive.  instead, we are going with a 2 foot clock.  i'm not entire sure about the end size, but you get the idea.  And just to be geeky, let's use GPS to snag the time with 100ns accuracy.  __ 

25 Second Shot Clock -  This is a circuit intended to be used in basketball shot clock __ Designed by Milardo de Guzman

28 LED Clock -  This is a programmable clock timer circuit that uses individual LEDs to indicate hours and minutes.12 LEDs can be arranged in a circle to represent the 12 hours of a clock face and an additional 12 LEDs can be arranged in an outer circle to indicate 5 minute intervals within the hour.4 additional LEDs are used to indicate 1 to 4 minutes of time within each 5 minute interval.   __ Designed by Bill Bowden

28V Power to Frequency Converter -  The LT2940 measures a high side current and a differential voltage, multiplies them and outputs a current proportional to instantaneous power.  Bidirectional high side currents and bipolar voltage differences are correctly handled by the four-quadrant multiplier and push-pull output stage, which allows the LT2940 to indicate__ Linear Technology/Analog Devices App Note, Apr 26th 2010

2D3 Nixie clock Schematic -  Schematic & contruction instructions __ Contact Peter @ Neontime

2-tone doorbell using 555 timer -  No circuit description, schematic only__ CdS Electronic

2-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.

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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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