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Last Updated: December 01, 2017 03:41 AM

Circuits Designed by Dave Johnson, P.E.

LED Test Signal Generator-40KhzThis 40KHz crystal controlled oscillator circuit drives an infrared LED with powerful 40ma pulses.  The circuit can be used to test optical communications circuits, designed to receive 40KHz modulated light signals . . . Hobby Circuit designed by Dave Johnson P.E.-February, 2002

Light to Frequency ConverterThis circuit uses a CMOS version of the classic 555 timer, to form a light intensity to frequency converter.  A small PIN photo diode is used as the light detector.  The pulses produced are short, so in some applications you may want to stretch them or . . . Hobby Circuit designed by Dave Johnson P.E.-May, 2008

Light/Dark 12V SwitchOften, for certain low voltage lighting systems; you would like to turn off the lights during the bright light of the day.  Most commercial day/night switches are designed for AC lighting.  The circuit below was designed for a 12v DC system.  But, it could be modified for other voltage as well.  It uses an inexpensive phototransistor as the light detector.. . . Circuit by David Johnson P.E.-June, 2008

Lighthouse LED FlasherThis was originally designed for a model in a HO train set.  It simulates the behavior of the light from a lighthouse.  The LED intensity gradually increases, then flashes with a bright light and finally decreases slowly in intensity. . . Circuit by David Johnson P.E.-July, 2006




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

 

 

C/control.htmPAGE 34

LED Strobe Light -  Schematic + Info + pictures __ Designed by Lennie Zink

LED Test Signal Generator-40Khz -  This 40KHz crystal controlled oscillator circuit drives an infrared LED with powerful 40ma pulses.  The circuit can be used to test optical communications circuits, designed to receive 40KHz modulated light signals . . . Hobby Circuit designed by Dave Johnson P.E.-February, 2002

LED Torch -  Based on the MAX660, designed to power three 3mm/5mm white LED's from 3V (1.5V min) , intended for replacing incandescent bulbs in small torches.   __ Designed by Submitted Andre

LED Blinker uses 4 parts -  EDN-Design Ideas March 26, 1998    [ NOTE : File has multiple design, scroll for this one.]   The circuit in Figure 1 is an easy-to-make attention-getter and runs for a week or longer on two AA cells. In September, I used this circuit for a school fundraiser, and it helped me generate more than $100. My dad showed me a circuit in EDN that did the same thing, but it uses more parts (see "Alternating LED flasher uses minimal parts," EDN, Nov 20, 1997, pg 104). __ Circuit Design by Andy Meng, Cincinnati, OH

Led Strobe 2 -  this version has been built and tested and is very simple indeedbased on alien project astable! __ Contact: P. Townshend EduTek Ltd

LED-flashlight works at voltages as low as 0.5V -  09/23/10 EDN-Design Ideas Extend the life of alkaline batteries.    __ Circuit Design by GY Xu, XuMicro, Houston, TX

LEDs Flasher Alternately -  Classic astable multivibrator using 2 transistors.  Transistor is not critical.  Try these: 2N4401, 2N2222, NTE123A, NTE123AP, NTE159, TUP/TUN and those in your junk box, you may find that most of them will work.   __ Designed by Tony van Roon  VA3AVR

LEDs or Lamps Sequencer -  Very simple, versatile modular design No limits to the number of modules used in the ring __ Contact: Flavio Dellepiane, fladello @ tin.it

Less Than 200 μA, Low Power, 4 mA-to-20 mA, Process Control Current Loop  -  Located at the control unit, the 12-bit AD5621 DAC produces an output voltage, VDAC, between 0 V and 5 V as a function of the input code.  The code is set via an SPI interface.  The ideal relationship between the input code and output voltage is given by where: V REF is the output of ADR125 and the power supply to the AD5621.  __ Analog Devices from the Lab

Level Crossing Lights -  Every model railway has a place where road and rail meet, and when it does, some form of warning is needed.  Flashing lights work well, but something is needed to drive them.  And that is where this circuit comes in.  All it does is flash lights and it is so simple anyone could build it! __ Contact: Collin Mitchell

Level indicator with 10 LED -  Schematic + PBC layout __ Jan Kolar

Level meter for home theatre systems -  Having trouble adjusting the levels in your home theatre system? This simple project makes the job easy.__ SiliconChip

Level-Shifts AC Signals -  10-Jul-03 EDN-Design Ideas AC signals can emanate from many sources, and many of these sources are incompatible with the most popular interface voltages, such as TTL.  A temptation always exists to capacitively couple the ac signals because capacitive couplin __ Circuit Design by Ron Mancini, Texas Instruments, Bushnell, FL

Leveraging the High-End Timer Transfer Unit on Hercules ARM Safety MCUs (Rev. A) -  The brushless DC motor has stator windings and permanent magnets on the rotor.  The windings are connected to the control electronics and there are no brushes and commutators inside the motor.  The electronics energize the proper windings similar to a commutator; the windings are energized in a moving pattern that rotates around the stator.  The energized stator windings lead the rotor magnet.   __ Designed by Texas Instruments App Notes, 6-Sep-11

Light / dark activated relay -  The potmeter adjust the trigger 'on' level.  The diode in the diagram shows to be 1N914.  This is ok if you have a light-duty relay, also the 1N914 is a signal diode so actually does not qualify.  Use a 1N4001 (Tony van Roon's or better) instead.  A couple of substitutes for the 2N2222 transistor are: NTE123A, ECG123A, PN100, etc __ Designed by Tony van Roon  VA3AVR

Light Activated Relay -  This is same circuit as above with the addition of a photo resistor to trigger the flip flop instead of a push button.  The bias resistor in series with photo resistor was chosen so that sufficient voltage is present at the base of the 2N3904 to supply current to the circuit in ambient lighting conditions __ Designed by Bill Bowden

Light bulb timer -  The circuit is rather small and could be housed in the same case as the push button, if there is enough room.  Of course you have to substitute the standard switch with a push button.  Operation with a 110Vac mains has not been tested although I expect that a 100μF 100V capacitor instead of the 47μF capacitor should do the trick

Light Chaser -  Schematic only __ Designed by Andres de la Plaza

Light Control Switch -  This is a simple LM311 Comparator based switch which can be used for various purposes: __ Designed by Nina Gajjar

Light Control SystE - M -  It is easy to install a couple of infrared emitter and receiver at the entrance of your room and maybe you connect them to the light, but you cannot control the light in this way! You will never know how many person inside and if the room is empty or not.  In this system, every thing is under control, because it is smart enough to know how many persons inside; and it can identify the direction of them, so the light will be turned OFF when the room is unoccupied; and ON otherwise! __ Contact: IQ Technologies

Light Controlled Switch -  Output a control signal suitable for relay depending on the light level

Light Controller -  On this page, I will introduce the Light controller with PIC16F873.  This circuit is usable only in the direct electric current.  It isn't possible to use for alternating current.  In this circuit, the following features of PIC16F873 are used.   __ Designed by Seiichi Inoue

Light Controller High Side -  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

Light Detector -  This circuit detects light falling on the Photo-cell (Light Dependent Resistor) to turn on the 555 and create a tone that is delivered to the speaker.  Pin 4 must be held below 0.7v to turn the 555 off.  Any voltage above 0.7v will activate the circuit.  The adjustable sensitivity control is needed__ 555-Timer

Light Detector -  NOTE :  Variable resistor R1 adjusts the light threshold at which the circuit triggers.  R1's value is chosen to match the photocells resistance at darkness.  The circuit uses a CMOS 4001 IC.  Gate U1a acts as the trigger, U1b and c form a latch.  S1 resets the circuit.  The output device may be a low power piezo buzzer. __ Designed by Mick Devine, UK

Light Dimmer -  This little circuit can be used to dim lights up to about 350 watts.  It uses a simple, standard TRIAC circuit that, in my expirience, generates very little heat.  Please note that this circuit cannot be used with fluorescent lights.   __ Designed by Aaron Cake

Light Dimmer that Doubles as Voltmeter -  Measure AC mains voltage without using a multimeter.  All you need to do is to slightly modify the light dimmer fitted at the base of a table lamp for use as...__ Electronics Projects for You

Light Organ for Car -  flashes3 low voltage Light, operates at10-25-Volt voltage, in PDF format, text in Finnish

Light to Frequency Converter -  This circuit uses a CMOS version of the classic 555 timer, to form a light intensity to frequency converter.  A small PIN photo diode is used as the light detector.  The pulses produced are short, so in some applications you may want to stretch them or . . . Hobby Circuit designed by Dave Johnson P.E.-May, 2008

Light to Frequency Converter -  Fout = –1.4kHz per microampere of photo diode current, IPD.  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__ Linear Technology/Analog Devices App Note, Jun 16th 2010

Light/Dark 12V Switch -  Often, for certain low voltage lighting systems; you would like to turn off the lights during the bright light of the day.  Most commercial day/night switches are designed for AC lighting.  The circuit below was designed for a 12v DC system.  But, it could be modified for other voltage as well.  It uses an inexpensive phototransistor as the light detector.. . . Circuit by David Johnson P.E.-June, 2008

Light/Dark Detector drives a relay -  This handy little circuit can tell the difference between darkness and light, making it very useful for switching on and off signs, porch lights or other things when it gets dark or light.   __ Designed by Aaron Cake

Lighthouse LED Flasher -  This was originally designed for a model in a HO train set.  It simulates the behavior of the light from a lighthouse.  The LED intensity gradually increases, then flashes with a bright light and finally decreases slowly in intensity. . . Circuit by David Johnson P.E.-July, 2006

Lights Control for Model Cars  NOTE : Must register on this site __ Designed by Published in Elecktor July/Aug, 2010

Lights timer -  Automatically turn off the lights after 10 minutes.  If you often forget to turn off the lights outside or at different places in the house, this circuit can be practical for you.  It can control two independent light switches with different turn off times.  Press the button once and the light turns on for the preset time.  Press again, and the light remains on forever.  Press for the third time, and the light turns off __ Designed by Peter Jakab

Limit switches control dc-motor H bridge -  03/05/09  EDN-Design Ideas Mechanical and electronic switches provide interlocks, preventing motors from overrunning their bounds __ Circuit Design by Andreas Grün, Wedemark, Germany

Line following Robot -  This is a tiny line following robot which can run on the desk.   __ Designed by The Electronic Lives Manufacturing-presented Chan

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