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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:

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

555 Timer IC Tester -  The 555-tester above is basically a LED flasher circuit but with the 555 removed.  imagen the output being a square-wave pulse with a high and low pulse, and is so indicated by the two leds, one 'Hi' and the other one 'Lo'.  When you have a good 555 under test.   __ Designed by Tony van Roon  VA3AVR

555 Timer MonoStable using Pushbutton -  The two circuits above illustrate using the 555 timer to close a relay for a predetermined amount of time by pressing a momentary N/O push button.  The circuit on the left can be used for long time periods where the push button can be pressed and released before the end of the timing period.  For shorter periods, a capacitor can be used to isolate the switch __ Designed by Bill Bowden

555 Timer Tester -  Test 555 timers quickly with this simple circuit.__ 

555 timer triggers phase-control -  05/31/13  EDN Design Ideas:  in this Design idea Classic from 1988 a 555 timer IC triggers a phase control circuit, allowing manual adjustment of power delivered to a load.  The control circuit in Figure 1a allows you to manually adjust the power delivered to a load.  By changing the setting of potentiometer R3, you change the phase angle at which the thyristor (Q3) fires (Figure 1b) , thereby altering the load current’s duty cycle.  The adjustment range is about 0 to 180°.  Q3’s off time is linear with R3, but of course the resulting load power is not linear with R3.   __ Circuit Design by JN Lygouras, University of Thrace, Xanthi, Greece

555 Timer Tutorial + Circuits -  What exactly is an OPerational AMPlifier? Let's define what that component is and look at the parameters of this amazing device.  An operational amplifier IC is a solid-state integrated circuit that uses external feedback to control its functions.  it is one of the most versatile devices in all of electronics.  The term 'op-amp' was originally used to describe a chain of high performance dc amplifiers that was used as a basis for the analog type computers of long ago.   __ Designed by Tony van Roon  VA3AVR

555 Tone Generator 8 Ohm Speaker -  This is a basic 555 squarewave oscillator used to produce a 1 Khz tone from an 8 ohm speaker.  in the circuit on the left, the speaker is isolated from the oscillator by the NPN medium power transistor which also provides more current than can be obtained directly from the 555 (limit = 200 mA).  A small capacitor is used at the transistor __ Designed by Bill Bowden

555 Triangle Waveform Generator -  The circuit is a triangle waveform generator that uses as few parts as possible.  A 555 timer IC , 2 resistors and two capacitors make the triangle wave.  The IC is connected in a 50% duty-cycle astable square-wave oscillator circuit.  The square-wave output is fed from pin 3 of the IC to an RC shaping circuit.  When the __ Designed by Popescu Marian

555 VCO -  By adjusting the voltage on pin 5, (the CONTROL pin) the frequency of the oscillator can be adjusted quite considerably.  __ 555-Timer

555 Voltage Doubler Relay Driver -  These novel relay driver circuits have the ability to pick up a relay with a coil voltage rating equal to double Vcc.  After pickup, the relay armature is held via the application of Vcc.  Under this condition, the coil power is reduced by the square of the voltage ratio, or to 25%.  This is the ultimate in relay economy—the __ Designed by Jim Keith

555-based class-D headphone driver makes great practice Amp -  07/28/14  EDN Design Ideas:  This class-D audio amp “plays” to the 555’s strengths. __ Circuit Design by Petre Petrov

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

5V Powered, Quartz-Stabilized 10kHz Voltage to Frequency Converter has 0.0015% Linearity & 8ppm/°C Temperature Coefficient -  Almost all precision voltage-to-frequency converters utilize charge pump based feedback for stability.  These schemes rely on a capacitor for stability.  A great deal of effort towards this approach has resulted in high performance V to F converters.  Obtaining temperature coefficients below 100ppm/°C requires careful attention __ Linear Technology/Analog Devices App Note, Mar 25th 2010

5x5x5 LED cube -  This month's featured Gadget Freak is provided by an old favourite of the blog, Peter Griffiths.  He shares all the details necessary to build your own 5 x 5 LED cube__ 

6 Digit 40MHz Frequency Counter Module -  Here is a design for a very low cost 6-digit frequency counter module using offshelf components (and not that expensive 74C926!).  The standard circuit will display directly in Hz (1MHz max) , and re is a separate on board divider that will allow you to display directly in KHz (approx 40MHz max).  Becausedisplay reads directly in Hz or KHz re is no __ Designed by David L. Jones

600 MHz to 2.2GHz VCO -  Schematic only __ Designed by va3iul

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

68HC11 Read Encoder -  The encoder is connected to PORTA PA0 and PA1 --  The board must be in BOOTSTRAB MODE (tested with Loggyboard)  __ Designed by Ludwig Orgler-Fachingenieur Elektrotechnik

68HC11 stepper Motor control -  Simple circuit with 16-pin Nitron chip 68HC908, easy analog setting, source code with IC C08.  New s-record for 8-pin 68HC908QT2!  __ Designed by Ludwig Orgler-Fachingenieur Elektrotechnik

7 Segment LED Counter -  This simple counter can be used to count pulses, as the basis for a customer counter (like you see at the doors of some stores) , or for anything else that may be counted.  The circuit accepts any TTL compatible logic signal, and can be expanded easily (see Notes)  __ Designed by Aaron Cake

7 segment rolling display using PC -  it is very interesting and convenient to be able to control everything while sitting at your PC terminal.  Here, a simple hardware circuit and software is used to interface a 7-segment based rolling display.  The printer port of a PC provides a set of points with some acting as input lines and some others as output lines.  Some lines are open collector type which can be used as input lines.  The circuit given here can be used for interfacing with any type of PC?s printer port.

Read more: http://www.electronic-circuits-diagrams.com/7-segment-rolling-display-circuit/#ixzz4fil0LLEN
Follow us: @eleczone on Twitter | electronicscircuitsprojects on Facebook__ 

72 LED Clock -  in the circuit above, 60 individual LEDs are used to indicate the minutes of a clock and 12 LEDs indicate hours.  The power supply and time base circuitry is the same as described in the 28 LED clock circuit above.  The minutes section of the clock is comprised of eight 74HCT164 shift registers cascaded so that a single bit can be recirculated through the 60 stages i __ Designed by Bill Bowden

74ACT74 makes low-skew clock divider -  12/17/98 EDN Design Ideas:  Serial-data systems often generate an internal clock at twice the data rate for mid-bit sampling or for generating bi-phase codes.  External equipment and some internal processes require a clock that runs at the data rate.  Simply dividing the twice-rate clock with a flip-flop generates a data-rate clock that is skewed by one logic delay with respect to the input.  This delay can be a significant fraction of the bit period.  You can use specialized PLL-based low-skew divider chips   Page includes several designs.  Scroll to find this one __ Circuit Design by JTom Napier, Consultant, North Wales, PA

7-segments 12/24 Hours LED clock with PIC 16F84A or 16F628A -  Almost No Parts Microcontroller based electronic circuit __ Designed by Jos Pino's Projects & Tidbits

8 Hints for Making Better RF Counter Measurements -  Application Note__ Aligent

8 Second to 8.5 Minute Low Frequency Clock (Intervalometer for Time-Lapse Photography) -  This circuit example highlights the use of the LTC6991 in a intervalometer for time lapse photography.  in this example the LTC6991 is configured as a self-resetting circuit and generates a fixed time pulse from 8s to 64s.  The LTC6991 is part of the TimerBlox family of versatile silicon timing devices with a programmable period__ Linear Technology/Analog Devices App Note, Oct 26th 2010

800 MHz to 2.2GHz Push-Pull VCO -  Schematic only __ Designed by va3iul

80186 timer pins provide general I/O -  08/01/98 EDN Design Ideas:  (FILE
has several circuit ideas.  Scroll to find this one.) intel's (www.intel.com]) 80186 is a highly integrated mP common in embedded applications.  it combines 15 to 20 common iAPX86 system components, such as a DMA controller, an interrupt controller, timers, a clock generator, a bus i __ Circuit Design by Sk Shenoy, NPol, Kochi, India

8254 Timer & Counter Board -  This is a photo of a general purpose timer/counter card you can wirewrap in a weekend.  it plugs into your PC's iSA bus just like a sound or modem card.  it gives high-resolution timing (microseconds).  Because of its programmablity, it is very powerful and flexible.  You can even control DC or servo motors using pulse-width modulated (PWM) , or stepper motors using its square wave capabilities.  The figure below is the actual output (square wave) from the 8254 card captured by an oscilloscope: __ Designed by Boondog web site

8-Bit Binary Counter -  Our binary COUNTER - B8 kit has many applications; Manual press the push button to count up to 2 ^ 8 (1 to 255 decimal) counts.  The binary counts will display on bright 8 LEDs!  Automatic, short the switch to automatically count again and again.  Draw attention and have fun!  The unique small design will allow you to mount it almost anywhere.  Simply connect the switch to your room door and you can count the number of time your brother "pick-in.  " Operate it with 9V battery, 12V car battery, four 1.5V batteries, or via one of our battery simulator kits __ Contact Kit from Elich Industrial Development, Corp

8-Digit Counter Works with Common Anode or Common Cathode -  07/15/10 EDN Design Ideas:  A classical design for directly driving eight seven-segment LED displays requires as many as 15 i/O lines.  Previous Design ideas - have described many approaches for using a maximum number of LEDs with a minimum number of i/O lines (references 1 through 5).  The following idea reuses one of these approaches to drive a maximum number of seven-segment LED displays, and it may be useful in designing a lowcomponent- count, low-power.    __ Circuit Design by Charaf Laissoub, Valeo Interior Controls, Créteil France

9 Second Digital Readout Countdown Timer -  This circuit provides a visual 9 second delay using a 7 segment digital readout LED.  When the switch is closed, the CD4010 up/down counter is preset to 9 and the 555 timer is disabled with the output held high.  When the switch is opened,  __ Designed by Bill Bowden

9 Second LED Relay Timer -  This circuit provides a visual 9 second delay using a 7 segment digital readout LED.  When the switch is closed, the CD4010 up/down counter is preset to 9 and the 555 timer is disabled with the output held high.  When the switch is opened,  __ Designed by Bill Bowden

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

 


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