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Timers and Counters Circuits

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

 

Last Updated: October 13, 2017 03:06 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:

Tan 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

Tanktwanger puts a new spin on clock synthesis -  02/03/97 EDN-Design Feature     An unusual circuit, the "tanktwanger, " provide as some clock-generating and -adjusting advantages over conventional clock-synthesis methods.  You can adapt the main circuit for numerous applications, but you must take care when constructing this VHF design.   __ Circuit Design by Glen Chenier, Fitel Photomatrix

Telephone Lamp -  Here is a White LED Lamp that turns on when the telephone rings.  The cool white light helps to locate the phone in darkness and also helps to note the message or telephone number.  The lamp remains on for three minutes then turns off.  The telephone lamp circuit is powered by a 9 volt PP3 battery and connected to the telephone __ Designed by D Mohankumar

Telephone Ringer using Timer ICs -  This circuit can produce ringing tones similar to those produced by a telephone for use in intercom operations.  __ Electronics Projects for You

Temperature to Frequency Converter -  This circuit directly converts temperature to digital data.  in this case, a thermistor sensor biases the RSET pin.  The LTC1799 frequency output is predictable, although nonlinear.  The inverse RSET vs frequency relationship combines with the thermistor’s nonlinear characteristic to give Figure 8’s data.  The curve is nonlinear, __ Linear Technology/Analog Devices App Note, Mar 26th 2010

Temperature-to-Frequency Converter -  Precision oscillator structure uses SCR effect to discharge integration capacitor.  A temperature dependent device (LM134) effects the integrator trip point to form a variable interval.  An output transistor detects the reset action and forms a logic pulse.  __ Linear Technology/Analog Devices App Note, Jun 21, 2011

Termination supply tracks one-half core voltage -  04/27/00 EDN Design Ideas:  Modern µPs typically require core voltages of 2 to 3V.  They also require "termination" voltages that, for best performance, should equal half the core voltage.  The problem is, core voltages vary among CPUs, and some systems even incorporate variable-core-voltageModern µPs typically require core voltages of 2 to 3V.  They also require "termination" voltages that, for best performance, should equal half the core voltage __ Circuit Design by Chester Simpson, National Semiconductor, Santa Clara, CA

Test Continuity -  This circuit will detect low resistances and high resistances to produce a tone from the speaker.  it will detect up to 200k and the circuit automatically turns off when the probes are not used.  __ 555-Timer

Test Continuity -  This circuit senses only dead shorts on a populated board.  it will not ring through or damage components.  it shuts off when not in use.  it was first published in Electronics magazine, June 21, 1979, page 145 __ Designed by Andrew R. Morris

Test Continuity -  This is another invaluable piece of test equipment for digital work.  it has been designed by us to cater for a particular application servicing digital projects sent in for repair.   __ Designed by Collin Mitchell

Test Human Reaction Time with the 555 IC -  With this simple circuit that is built with the 555 IC you can test human reaction time.  You can find out how fast do you react by trying to catch a flashing LED.  How does the human reaction tester works? When S1 is ON the circuit acts as a astable multivibrator and the LED is lit for about 0.1second and is flashing every 1.5 __ Designed by Popescu Marian

Test timer -  The output goes high for a fixed period of time when power to a unit under test (UUT) is turned on, and again when it is turned off.  it was used with a magnetic sensor to test the spin-up and spin-down time of a gyroscope.   __ Designed by Andrew R. Morris

Tester Continuity -  Among the essentials for circuit design and prototyping is the continuity tester, a simple device which provides an audible indication when a sufficiently low resistance is applied between its input probes.  This version has a feature which automatically turns off the tester after about two minutes, thereby saving the 9 volt battery from inadvertent discharge.  The tester produces a high-pitch tone when less than 10 ohms is placed between the input probes.  The 10 ohm threshold is a convenient value that indicates hard-wired paths, but excludes indications for circuit paths through most components.  in addition, the amount of current presented to the circuit by this __ Designed by Arthur Harrison

The 555 Timer -  (spice design)  __ Designed by Rick 

THE FOX-250mW transmitter with timer -  The timer consists of a Radio Shack travel alarm.  I disconnected the pizeo-ceramic beeper and used the signal to set a flip-flop built from a CMOS 4011.  The output of the flip flop is connected to a switching transistor which supplies voltage to the CW iD.  I used an R/C combination on the flip/flop so it would be reset when first powered up.  A push button is provided so the flip/flop can be set manually (turning on the transmitter)  __ Designed by Joe Leggio WB2HOL

THE FOX-two transistor 40 milliwatt fox transmitter -  This two transistor 144 MHz transmitter uses a 48 MHz scanner crystal as an oscillator / tripler.  A second transistor boosts the power output to 40 milliwatts.  A 7-element filter is used to minimize output on the third harmonic. (I did not want it to be easy to RDF this on the 450 MHz third harmonic)  __ Contact Joe Leggio WB2HOL

The HC11 Controls the Stepper -  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

The Kicker -  A simple circuit that momentarily closes a pair of contacts at long intervals.  Useful when you need to kick something into action every few hours or days.   __ Designed by Burton Lang

The Science of Timekeeping -  Application Note__ Aligent

The SportSync Audio Delay Module -  Many sports fans feel that radio commentary is better than that on TV, particularly commercial TV.  To eliminate the annoyance of the TV commentary (and the adverts) they want to turn down the sound on the TV and listen to the radio instead.  But the delay in the live TV broadcast causes a major problem.  This simple project lets you delay the commentary on the radio to match the action on your TV - and it's remote controlled.__ SiliconChip

Three Fake Alarms -  Battery Powered LED Circuits:  Flashing LEDs can be used to create the impression that an alarm has been fitted.  Or they can be used in conjunction with a real alarm - to warn-off a potential thief.  These three small circuits will flash anything from a single LED - up to 90 LEDs and beyond - with a variety of speeds and patterns.  __ Designed by Ron J.

Three transistor 750 milliwatt fox transmitter -  This three transistor 144 MHz transmitter uses a 48 MHz scanner crystal as an oscillator / tripler.  A second transistor boosts the signal to 40 milliwatts, a third amplifies the power output to 750 milliwatts. __ Contact Joe Leggio WB2HOL

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

Ticking Bomb -  This circuit sound just like a ticking bomb.  __ 555-Timer

Tilt Switch -  The output is LOW at start-up due to the capacitor on pin 4.  When the mercury switch closes, the output goes HiGH and remains HiGH until the reset button is pressed.  This circuit is called a LATCH.  __ 555-Timer

Time Delay Generator -  Circuit ideas for Designers App Note__ Advanced Linear Devices, Inc

Time Delay Relay -  A time delay relay is a relay that stays on for a certain amount of time once activated.  This time delay relay is made up of a simple adjustable timer circuit which controls the actual relay.  The time is adjustable from 0 to about 20 seconds with the parts specified.  The current capacity of the circuit is only limited by what kind of relay you decide to use __ Designed by Aaron Cake

Time Delay Relay II -  When activated by pressing a button, this time delay relay will activate a load after a specified amount of time.  This time is adjustable to whatever you want simply by changing the value of a resistor and/or capacitor.  The current capacity of the circuit is only limited by what kind of relay you decide to use __ Designed by Aaron Cake

Time Delay Relay-Power OFF -  The two circuits below illustrate opening a relay contact a short time after the ignition or ligh switch is turned off.  The capacitor is charged and the relay is closed when the voltage at the diode anode rises to +12 volts.  The circuit on the left is a common collector or emitter follower and has the advantage of one less part since a resistor is not needed in series with the transistor base.  However the voltage across the relay coil will be two diode drops less than the supply voltage, or about 11 volts for a 12.5 volt input. __ Designed by Bill Bowden

Time Delay Relay-Power ON -  Here's a power-on time delay relay circuit that takes advantage of the emitter/base breakdown voltage of an ordinary bi-polar transistor.  The reverse connected emitter/base junction of a 2N3904 transistor is used as an 8 volt zener diode which creates a higher turn-on voltage for the Darlington connected transistor pair.  Most any bi-polar transistor may be used, but the zener voltage will vary from about 6 to 9 volts depending on the particular transistor used.  Time delay is roughly 7 seconds using a 47K resistor and 100uF capacitor and can be reduced by reducing the R or C values. __ Designed by Bill Bowden

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

Time Switch V1.0 -  New weekly scheduler made by 68HC908QY4 with kaypad and 16x1 line LCD!  (not recommended)  __ Designed by Wichit Sirichote

Time-Controlled Switch using PIC16f72 -  APRiL 2012: A time-controlled switch is an automatic timer switch that turns an appliance ‘on’ for the desired time duration.  After the preset time duration, the timer automatically switches off, disconnecting...__ Electronics Projects for You

Timed Beeper -  Beeps 7.5 seconds after a preset Time Adjustable Time settings:15 sec.30 sec.1 min.2 min.  & others __ Contact Flavio Dellepiane, fladello @ tin.it

Time-delay relay reduces inrush current -  03/07/02 EDN Design Ideas:  A transformer switching onto a line can sometimes cause a circuit breaker to trip or a fuse to blow.  This phenomenon occurs even if the transformer presents no load, such as when the secondary is open.  The problem arises because of the heavy magnetizing inrush current in the transformer.  The amplitude of the current depends on the instant on the ac waveform at which the transformer become __ Circuit Design by P Seshanna, Assumption University, Bangkok, Thailand

Time-lapse photography with a QuickCam -  Something I'vewanted to do for quite some time is a time lapse movie of a static view, spanning an entire year.  it could be presented in a number of ways, for example a fast 12-second (30fps) view of one exposure at noon every day, or a longer sequence covering all the daylight hours, equalized for brightness, or an even longer one covering all hours.  Also I would want to make a 2-dimensional graphic, 365x240 pixels, one for every 10 minutes of the year, with the pixel colour being the average colour of a small patch of sky. __ Designed by Markus Wandel

Time-Lapse Photography with Raspberry Pi 3 -  This project aims at developing a simple time-lapse photography device with Raspberry PI 3 and PI camera. To get the most out of nature without tiring yourself, time-lapse photography is the best...__ Electronics Projects for You

Timer automatically shuts off -  08/17/00 EDN Design Ideas:  The circuit in Figure 1 is a programmable power switch that offers on-state periods of 5 sec to three hours.  it consumes zero power in the off state and has zero voltage drop in the on state.  S1 is a power-on switch.  When you press S1, the battery powers an eight-pin PIC 12C508 µC __ Circuit Design by Yongping Xia, Teldata Inc, Los Angeles, CA   

Timer chip makes universal solenoid drive -  09/01/95 EDN Design Ideas:  Mechanical actuators that develop a force from magnetic interaction operate efficiently with high power until seated (the pull-in state).  You should then reduce the power to a lower holding level.  These rules are especially true for long-stroke solenoids.  Currently, the only available solenoid-driver ICs  are Motorola's MC3484 Series and National Semiconductor's LM1984, which are both designed to drive automotive fuel injectors.  Upon activation, either IC ramps the current to a peak value and switches to a holding current that is one-fourth as large.   __ Circuit Design by Richard Panosh, Vista, Bolingbrook, IL

Timer Controls DSP-Filter Frequency Resolution -  04/13/95 EDN Design Ideas:  To implement low-frequency digital filters, you can use low-power microcontrollers instead of dedicated DSP IC s.  However, using 8-bit or even 16-bit math can quickly lead to significant filter dynamic-range errors and to complicated routines for precise digital-filter coefficients.  By using a µC's 8-bit timer to set the sampling rate for a digital filter's data processing, you can obtain finer frequency resolution while using simple math routines. __ Circuit Design by D Hayden, Tempo Research, Vista, CA

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

Timer for Battery-Powered Tools -  Most hobbyists will have some tools that are battery-powered, such as a drill, screwdriver or power scissors.  Unfortunately (and especially with cheaper devices) the batteries often seem to be empty when you need to use such a tool.  must register on this site __ Designed by Published in Elecktor July/Aug, 2010

Timer for Darkroom -  This is a circuit for darkroom timer that can produce musical tones after an interval of one second.   __ Designed by © EFY Enterprises Pvt. Ltd.

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

Timer for Fans & Lights -  This simple circuit provides a turn-off delay for a 230VAC light or a fan.  it can be used to make a bathroom fan run for a set period after the switch has been turned off or it can be used with a pushbutton to turn a light on for a specific time.  The timer circuit consumes no standby power when the load is off.__ SiliconChip

Timer for Geyser -  This timer circuit for geyser sounds an alarm after the set timing of 22 minutes when the water is heated up.  The circuit comprises a timer IC 555 wired as an astable...__ Electronics Projects for You

Timer for Mosquito Destroyer -  in electric-heating mosquito repellents, an electric vaporiser heats up a mat or liquid to release non-degrading chemicals into the air and keep the mosquitoes away from the closed surroundings.  Here's a circuit...__ Electronics Projects for You

Timer From Old Quartz Clock -  You can build an accurate, low-cost timer from the circuit of an old quartz clock.  This timer has a time duration of up to two hours, which is sufficient for most...__ Electronics Projects for You

               >>> 

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

 


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