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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. :
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

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

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

A 12V Digital Timer using a 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

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

A 555 -Timer Based Motorcycle Alarm -  Motorcycle Alarm Circuits:  This circuit features an intermittent siren output and automatic reset.  it can be operated manually using a key-switch or a hidden switch; but it can also be wired to set itself automatically when you turn-off the ignition.  By adding external relays you can immobilize the bike, flash the lights etc. Now With Free SiMetrix Circuit Simulation.  __ Designed by Ron J.

A 555-based solar engine - Type 2 (time-controlled) Solar Engines -  in March of 2003, Manfred Schaffran posted a solar engine design using a 555 timer IC .   Wilf Rigter simplified this circuit a bit, made it phototropic, and doubled it up to yield a photopopper design in a post later the same day.  I'vegot this design written up elsewhere in the library. __ Designed by  Manfred Schaffran & Wilf Rigter

A 600MHz Frequency Counter -  This cheap but high performance frequency counter was originally developed as a project for the members of the Adelaide Hills Amateur Radio Society to construct, but proved massively popular with around 110 units being built by members of both AHARS and SCARC (South Coast Amateur Radio Club).  The counter is available in two styles, with a cheap but adequate quartz crystal oscillator being used as the time base in the most basic realisation.  in the second version, the time base used is a precision 10MHz TCXO, which lifts the performance of the counter to truly professional standards. __ Designed by VK5JST / VK5TR

A clock for all reasons, part 1: Monolithic oscillator invigorates instrumentation applications -  06/26/03  EDN Technical Article: in addition to their common role as clock sources in digital systems, oscillators play an important role in instrumentation applications.  A simple and tunable oscillator boosts the performance of a range of circuits.  Part 1 of this series presents an RTD digitizer, thermistor-to-frequency converters, and relative-humidity digitizers.   __ Circuit Design by Jim Williams, EDN's most revered contributor, passed away in June 2011 after a stroke.  He was 63.

A clock for all reasons, part 2: Monolithic oscillator invigorates instrumentation applications -  07/10/03  EDN Technical Article: Part 1 of this series presented a variety of circuits that use a monolithic oscillator in various applications.  Part 2 continues with more examples: chopped amplifiers, sine-wave generators, an interval generator, and an ADC.   __ Circuit Design by Jim Williams, EDN's most revered contributor, passed away in June 2011 after a stroke.  He was 63.

AN12 - Circuit Techniques for Clock Sources -  Linear Technology AN12 __ Designed by Jim Williams - Oct 1st, 1985

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

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

AN79 - 30 Nanosecond Settling Time Measurement for a Precision Wideband Amplifier -  Linear Technology AN79 __ Designed by Jim Williams - Sep 5th, 1999

An LED Flasher with a SlowRise & Fall Time -  Here is a Simple Circuit to give a Flashing LED, With a "Rising and Falling" Brightness.  it Uses the Sawtooth waveform from pins 2 and 6 to create the rise and fall.  The Resistor and LED on Pin 3 are Optional.  The 10K Potentiometer give a reasonable range of Speed.   __ Designed by G.L. Chemelec

An Up / Down Digital Counter with 7 Segment LED Displays -  REViSED   Really as Simple as you can get and has 4 Displays __ Designed by G.L. Chemelec

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

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