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Last Updated: June 02, 2021 01:44 PM

Circuits Designed by Dave Johnson, P.E.

Five-Watt Fluorescent Lamp Intensity ModulatorThe circuit was designed to experiment with using small fluorescent lamps as a broad pattern source of modulated light.  The circuit hits the small lamp with narrow 1us pulses at a rate of 10KHz.  Each pulse launches about 10 watts of visible light.  The lamp. . . Circuit by David Johnson P.E.-June, 2000

Flashing High-Power LED -  Power LEDs are becoming more popular these days.  The DC input power to these devices ranges from 1 watt to 5 watts.  Normal LEDs only receive about 0.  05 watts.  At this higher power, these devices can emit a lot of light . . . Dave Johnson, Lubbock TX (Aug 10, 2008)-DC Magazine - Issue 7 Mar 2010

Flashing LED Advertising Badge #1I have seen numerous flashing light badges at trade shows and conventions.  They are often handed out as gifts to promote some business.  The devices often use inefficient circuits, which cause the battery power source to be quickly depleted . . . Hobby Circuit designed by David Johnson P.E.-March, 2002

Flashing LED Power Indicator This circuit flashes a power indicator LED to keep the average current low. . . Circuit by David Johnson P.E.-June, 2000




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

F84 Miniature Real-Time Controller -  Build a simple real-time controller with PIC16F84 running at low power X-tal 32, 768Hz.  Daily scheduler for 6-channel resided in 64-byte EEPROM can easily be pre-programmed using Nigel PicProg __ Designed by Wichit Sirichote

Fader Switch Uses Inexpensive Controller -  12-Nov-09 EDN-Design Ideas Control the brightness of an LED or incandescent lamp Design by William Grill, Lenexa, KS

Fading Lights -  Suitable for 230V incandescent bulbs; Ideal for Christmas decorations __ Contact: Flavio Dellepiane, fladello @ tin.it

Fake Alarm Blinker -  Get an old used alarm panel with keypad, remove the standard internal electronic board, add this circuit and a 3.6V lipo battery.  Push one button for blink, and another button for off.  This way you fool stupid people to think you got a real alarm unit installed, so they go some where else and brake in. __ Designed by Thomas Scherrer OZ2CPU

Fan control -  P1 10k ohm potentiometersets the low speed(voltage) of the fans at the cool temperature.  P2 50K ohm potentiometersets the gain of the circuithow fast the voltage will rise to full output when the temp is higher__ Contact: IQ Technologies

Fan control -  As we begin to enjoy those lazy hazy days of summer, the most important thing on most of our minds is how to keep cool during those hot days.  For some of us that means turning up the old air conditioner and sipping on a nice cold glass of our favorite soft drink.  However, we often forget about an equally important __ Designed by Radio Amateur Society of Norwich

Fan Controller -  Th1, the 50K thermistor, is a standard type.  Mine was a bar or rectangular looking thingy.  Available from Tandy/Radio-Shack.  Almost any type will do.  I experimented with different models from 22K to 100K and all worked fine after replacing the trimmer pot.  The one used in the above circuit diagram was a 50K model.  This 50K was measured at exactly 25 °C and with 10% tolerance.  The resistance increases as the surrounding temperature decreases.  Tolerance for my application (cooling a large powersupply coolrib) is 10%.   __ Designed by Izhar Fareed

Fan controller adapts to system temperature -  09/25/97 EDN-Design Ideas Any piece of electronic equipment--whether it be a lab instrument, an audio amplifier, or a PC--that relies on a cooling fan to control internal temperature is a potential source of noise pollution or even hearing damage.  Most of the time, the fan's noise level is probably much higher than necessary, because it has enough capacity to move Design by Kerry Lacanette, National Semiconductor, Tucson, AZ

Fan controller made efficient with an Audio Amp -  11/09/00 EDN-Design Ideas You can use discrete transistors to vary power to a fan to control its speed.  However, with a simple modification, you can use an audio-amplifier IC to control a fan module  (Figure 1).  The LM4872.   PDF contains multiple circuits, scroll to find the one of interest Design by Wallace Ly, National Semiconductor Corp, Santa Clara, CA

Fan Dual-Controller -  Each fan turns off when the temperature drops 5 degrees below its turn-on temperature.  For example, if the dial is set to 80 degrees, the fan turns on at 80 degrees and turns off at 75 degrees.  This prevents the fan from cycling on and off rapidly, which would occur if the fan turned on at 80, started to cool the cabinet, and then immediately turned off at 79.  

Fan On/Off Control By Light -  This circuit lets you turn on/off a fan by just directing torchlight or other light toward its light-dependent resistor (LDR).  The circuit is powered from a 5V power supply.  Preset VR1 and...__ Electronics Projects for You

Fan Remote Control -  November 09, 2011Design News:  The gadget comes with off/on, three fan speeds, and multicolored LEDs to indicate the fan’s speed.  As a bonus, it beeps to indicate that the fan got your message.   __ Designed by Andrew R. Morris, Gadget Freak-Case #198, Design News

Fan Speed Controller -  Simple circuit for fan speed control based on thermal feedback.  To reduce product noise.  Design Idea   was rejected! Years later companies are making millions from such circuits.   __ Designed by Jim Haggerman, Hagerman Technology LLC

Fan Speed Temperature Controller-DH8AG -  Schematic only __ Designed by va3iul

Fan Thermostat -  Build a simple fan thermostat with LM35, ADC0804 and 89C51.   __ Designed by Wichit Sirichote

Fan Timer Based On Motorola 68HC908QT2 -  My son got his fan in the bedroom.  The fan has mechanical timer for 0-180mins.  One day it broken.  So I got the idea to use Nitron chip to replace the mechanical timer.  Someone may ask me why so complicated timer made by microcontroller chip? Actually we can build a timer with 555 and a 14-stage CMOS counter! The 555 runs astable with time constant controlled by RC and for long period timing we can divide the output frequency of 555 by a CMOS counter.   __ Designed by Wichit Sirichote

Fancy LEDS -  The idea of this project came from my youngest son.  He was dreaming of a small tool able to write symbols or pictures on a screen.  As a graphic LCD (even bought at Crownhill :)) was too expensive (or too easy??) , the solution adopted was to pilot a matrix of Leds.  This way, 

Fantastic Atom Expander -  Here is the schematic, PC board pattern, and parts placement for a "Fantastic Atom Expander".  This circuit produces an "exploding atom" effect using 98 LEDs. __ Designed by Aaron Cake

Farmhouse Lantern-Cum-Flasher -  This circuit uses a dual op-amp IC LM358 and two transistors.  It can be powered by a 6V maintenance-free rechargeable battery or a lead-acid accumulator type battery.  It has two modes...__ Electronics Projects for You

Fast, Portable Light Pulser -  10/16/03  EDN-Design Ideas The absence of a fast one-shot multivibrator in the entire TTL family, as well as the low-voltage swing and unwieldy supply requirements of ECL, drove us to exploit the fast transition times and low propagation delays of F-series g Design by SK Kaul and IK Kaul, Bhabha Atomic Research Centre, Trombay, Mumbai, India

Ferromagnetic soldering iron control -  EDN-Design Ideas 05/15/2014     Utilize a basic materials property to sense and control soldering iron temperature. Design by sajjad Haidar

Finally-A Decent Space Heater Thermostat -  an electronic thermostat that senses actual room temperature.  He tested and tweaked the design to get the proper control range and hysteresis.   __ Designed by Andrew Morris designed Gadget Freak-Case #218 6/29/2012

Fine Control SuperBright LED Pulser -  Four timing controls12V supply; Suitable for Halloween or Christmas props __ Contact: Flavio Dellepiane, fladello @ tin.it

Finely Tune the Hue of Blue-Light Sources -  03/17/11  EDN-Design Ideas Get 32 grades of hues between royal-blue and cyan.  When coach cars of long-range trains comprised compartments for six to eight passengers, the passengers could choose either “white” or deepblue light.  The blue light helped passengers sleep, even when they were not in full darkness.  The circuit in Figure 1 lets you set a hue of blue light that can match your favorite blue color.  Although you can accomplish this task with another circuit (Reference 1), this circuit provIdeas a finer adjustment of color and uses a narrower range from cyan to royal blue.  The light is a mixture from two power LEDs, both from Avago Technologies.   Design by Marián Štofka, Slovak University of Technology, Bratislava, Slovakia

Finite State Machine Programmable Logic Controller -  Finite State Machine based Programmable Logic Controller.7 Inputs  8 Outputs  Simple IF/THEN/ELSE based compiler language generates direct EPROM files.   __ Designed by David L. Jones

Fire Stick infrared Remote Control -  This article will show you how to build your own version of the Fire-Stick infrared remote control system.  The Fire-Stick has been an extremely popular, and HOT selling item here at Rentron.  com for quite a long time.  The LITEON infrared receiver modules originally designed-in to the Fire-Stick have been discontinued, and forced us to re-design the original circuit boards.   __ Designed by Reynold's Elec

Firefly Lights -  This firefly lights flasher is an easy, fun project.  It can be built on the tiny circuit board, or on perf board.  Specifications Battery life: approx 1 year using the NXP 7555 CMOS timer IC & standard alkaline battery, or about 6 months using the more common TI TLC555 Flash rate: approx 0.25 Hz (unless using optional __ Designed by Jim Keith

Five Equals Four with a Diode OR -  5-Jun-06 -Design News:   Trailer rental firms insist that tow vehicles provide operating lightsturn, tail and brake lights for every towed vehicle rented.  Easy to do if the tow vehicle is wired that way, but a pain if it has separate turn and stop lamp circuits.  John's solution is a pair of diodes, some quick __ Gadget Freak-Case #85

Five-Watt Fluorescent Lamp Intensity Modulator -  The circuit was designed to experiment with using small fluorescent lamps as a broad pattern source of modulated light.  The circuit hits the small lamp with narrow 1us pulses at a rate of 10KHz.  Each pulse launches about 10 watts of visible light.  The lamp. . . Circuit by David Johnson P.E.-June, 2000

Flash Slave Trigger -  Flash slaves are used when you need to supplement1-flash unit with1-or several more.  This slave trigger simply triggers those other units.  It does this by "seeing" the first flash (using a phototransistor) and triggering the other flashes a few microseconds later.  The sensitivity of the circuit is adjustable to compensate for ambient light or dimmer than usual master flashes.   __ Designed by Aaron Cake

FlasherLEDs -  This is a very simple project using a printed circuit board and 8 components.  It will flash an ordinary 3mm or 5mm (1/8" or 1/4") LED at a rate of about one flash per second.  

Flasher for Deepawali -  Here is the circuit for a portable electric lamp-cum-LED flasher.  It uses a 25W, 230V AC bulb and nine LEDs.  When the bulb glows all the LEDs remain 'off, 'and when...__ Electronics Projects for You

Flashing High-Power LED -  Power LEDs are becoming more popular these days.  The DC input power to these devices ranges from 1 watt to 5 watts.  Normal LEDs only receive about 0.  05 watts.  At this higher power, these devices can emit a lot of light . . . Dave Johnson, Lubbock TX (Aug 10, 2008)-DC Magazine - Issue 7 Mar 2010

Flasher Operates Off AC Mains -  06/23/11 EDN-Design Ideas A few components create an illuminated switch.  Looking for a mains switch in the dark is easier if the switch contains a built-in neon or filament miniature lamp.  Adding a small indicator to any mains switch is heLPFul.  It is even better if the indicator flashes.  This circuit makes a simple flasher using only four discrete components (Figure 1).   Design by Noureddine Benabadji, University of Sciences and Technology, Oran, Algeria

Flasher/Dimmer Lantern -  The electronic lantern control circuit adds high-efficiency dimming and flashing to an existing battery-powered lantern or flashlight or to a custom design.  For the car it makes a great lamp for changing a flat tire, back seat reading or emergency engine work.  The flasher mode __ Designed by Tony van Roon  VA3AVR

Flashing / pulsing third brake like for cars -  DN15:  Flashgun converter

Flashing Beacon -  A flashing beacon has many uses.  It can be employed as a distress signal on highways or as a direction pointer for parking lots, hospitals, hotels, etc.  Here we present a...__ Electronics Projects for You

Flashing Birthday Heart -  This circuit was made for my wife's birthday.  It is capable of flashing five strings of LED's with different frequencies.  It also has a connector for an 8 Ohm loudspeaker and two connectors for the small PCB's that are contained in musical greeting cards.  In this way the circuit will play alternatingly two room filling tunes at regular time intervals.  After a w __ Designed by Michel Van den Bergh On Electronics

Flashing Headlight for Mobikes -  The dipper for a vehicle’s headlight changes the light from high beam to low beam or vice versa given a particular set of road conditions.  The shifting of light from high...__ Electronics Projects for You

Flashing Heart -  This circuit was made for my wife's birthday.  It is capable of flashing five strings of LED's with different frequencies.  It also has a connector for an 8 Ohm loudspeaker and two connectors for the small PCB's that are contained in musical greeting cards.  In this way the circuit will play alternatingly two room filling tunes at regular time intervals.  After a w __ Designed by Michel Van den Bergh On Electronics

Flashing High Intensity LED 3rd Brake Light -  This circuit to make a flashing 3rd brake light assembly was designed to be easy to locate all the needed components and reasonably in expensive to build__ National Semiconductor

Flashing Indicators -  Need to flash "turn indicators" using a 555 and a single 20 amp relay.  Here is our suggestion.  The timing resistor needs to be selected for the appropriate flash-rate.  __ 555-Timer

Flashing LED -  This simple project makes a good low-cost first project to check your soldering skills and learn to identify common components.  The LED flashes at about 3Hz (3 flashes per second).   __ Designed by John Hewes

Flashing LED Advertising Badge #1 -  I have seen numerous flashing light badges at trade shows and conventions.  They are often handed out as gifts to promote some business.  The devices often use inefficient circuits, which cause the battery power source to be quickly depleted . . . Hobby Circuit designed by David Johnson P.E.-March, 2002

Flashing LED Power Indicator -  This circuit flashes a power indicator LED to keep the average current low. . . Circuit by David Johnson P.E.-June, 2000

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