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Last Updated: December 25, 2017 01:48 PM

Circuits Designed by Dave Johnson, P.E.

Drive a LED with an Intensity Ramping ModeThe circuit below was designed to drive a LED with an intensity ramping mode.  Two 555 timers generate two different triangle waveforms.  The upper device generates a 10KHz signal while the lower unit produces a 1Hz signal.  The two signals are fed to a . . . Hobby Circuit designed by David Johnson P.E.-December, 2007

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

Dimming DALI Ballast for 32w/T8 110V Input -  This reference design is a high efficiency, high power factor, digital dimming electronic ballast designed to drive rapid start fluorescent lamp types.    

Dimming DALI Ballast for 36w/T8 220V Input -  This reference design is a high efficiency, high power factor, digital dimming electronic ballast designed to drive rapid start fluorescent lamp types.

Diode-turn-on-time-Induced failures in switching regulators -  01/08/09  EDN Technical Article: Never have so many had so much trouble with so few terminals.  Most circuit designers are familiar with diode dynamic characteristics, such as charge storage, voltage-dependent capacitance, and reverse recovery time.  Manufacturers less commonly acknowledge and specify diode forward turn-on time.  This parameter describes the time required for a diode to turn on and clamp at its forward-voltage drop.  Historically, this extremely short time, measured in nanoseconds, has been so small that user and vendor alike have essentially ignored it.  They rarely discuss and almost never specify it.  Recently, switching-regulator clock rate and transition time have become faster, making diode-turn-on time a critical issue.   __ Circuit Design by Jim Williams, EDN's most revered contributor, passed away in June 2011 after a stroke.  He was 63.

Disco Lights -  software and hardware for controlling disco lights from your PC

Disco Style Strobe Light -  The stoboscope tube needs about 250-400V DC to operate.  This high voltage is generated using simple voltage step up circuit built from transistors Q1, Q2 and transformer T1.  This circuit gives out about 230V AC voltage which is then rectified with rectifying bridge U1 (must have at least 400V voltage rating) and stored to the main capacitor C1 __ Designed by Tomi Engdahl

Disconnect Load from Battery -  03/14/96 EDN-Design Ideas To prevent battery damage, the circuit in Figure 1 disconnects the load at a predetermined level of load voltage.  This load voltage, VTRIP, is closely proportional to the battery voltage.  R1 and R2 determine the level of VTRIP  that corresponds to voltage of 1.15V at pin 3 of IC1.  A voltage of 1.15V at pin 3 of IC1 causes the internal comparator to trip.  Thus, VTRIP=1.15(R1+R2)/R1 __ Circuit Design by Michael Keagy, Maxim Integrated Products, Sunnyvale, CA

Disconnect Load from Low-Voltage Supply -  04/24/03  EDN-Design Ideas Circuit ensures safety in power-on operation.  Power supplies often include a circuit that disconnects the load when the supply voltage drops too low, such as when a battery is nearly discharged.  A p-channel MOSFET connected between supply and load is the typical approach.  However, a 1.5V single-cell battery or other low-voltage supply is insufficient to fully turn on the MOSFET.  For such low-voltage systems, consider the circuit of Figure 1.   __ Circuit Design by Steve Caldwell

Discrete component Motor direction controller -  This circuit can control a small DC motor, like the one in a tape recorder.  When both the points A & B are "HIGH" Q1 and Q2 are in saturation.  Hence the bases of Q3 to Q6 are grounded.  Hence Q3, Q5 are OFF and Q4, Q6 are ON.  The voltages at both the motor terminals is the same and hence the motor is OFF.  Similarly when both A and B are "LOW" the motor is OFF.  When A is HIGH and B is LOW, Q1 saturates, Q2 is OFF.  The bases of Q3 and Q4 are grounded and that of Q4 and Q5 are HIGH.  Hence Q4 and Q5 conduct making the right terminal of the motor more positive than the

DIY Power Pulse Controller -  This device uses a built in pulse width modulated signal generator circuit for triggering a power MOSFET.__ © RMCybernetics

DIY remote control based on PIC -  Control up to 8 devices by this easy constructable remote control.  It can work as a radio or infrared remote control, depending on the components.  Each device output can be configured to be momentary (turned on while you press the button) or latched.  Latched outputs can be toggled on/off by one button per channel, or turned on and off by two buttons per channel __ Designed by Peter Jakab

D-I-Y remote control for a Model train layout. -  All you need is a picaxe, some code and a pair of pre-built UHF modules (plus a few minor parts.__ SiliconChip

Dog Whistle -  It's well known that many animals are particularly sensitive to high-frequency sounds that humans can't hear.  Many commercial pest repellers based on this principle are available, most of them operating in the range of 30 to 50 kHz.   __ Designed by Tomaz Lazar-Ljubljana, Slovenia

Dome Lamp Dimmer -  A reading light inside the car greatly assists passengers during night, but often the interior dome lamp is too bright and distracting to the driver.  A linear regulator such as a...__ Electronics Projects for You

Dome Lamp Dimmer -  This unique circuit makes your dome light look cool.  Usually when the car door is closed, the dome light just goes OFF.  With this circuit, you can have our dome light fade slowly.   __ Contact: Charles Wenzel of Wenzel Associates, Inc.

Dome light dimmer (with Delay) -  For all you guys out there that want a fading dome light (aka courtesy light aka theatre lighting) without having to pay for one, you can build your own.  I have attached the schematics and you can build it for a few bucks given that you don't have any spare components lying around otherwise it can cost you absolutely nothing.  Of course you can rip some parts from your TV, CD player, radio, etc.  , but I'm not responsible for the damage you cause this way [b:e43bc460fa]The way it works[/b:e43bc460fa] I won't bother you with technical

Dome Light Extender -  There are countless dome light extenders on the Net and in magazines, but most of them suffer from one problem complexity.  Ok, they are not actually complex, but most are far more complex than they need to be.  Some are completely over the top, and require additional car wiring, a PCB, ICs, trimpots and lots of other stuff, while others seem to be someone's untested idea or maybe just a brain fartsome circuits I saw will never work.  My goal was extreme simplicity, and I think that has been achieved.   __ Designed by Rod Elliott  ESP

Door mirror Controller -  As for the recent car, the door mirror is popular thing and the electromotion housing type is used usually.  Even my car is a door mirror type, but the electromotion housing function was not attached __ Designed by Seiichi Inoue

Doozy requiring some parts you can't get at the 'Shack. -  You can make a doozy of a xenon strobe using the 12 volt DC in, DC output mercury lamp ballast here at http://www.  donklipstein.  com/ebdc12.  html.  You may run into a problem with the flashtube arcing continuously after a flash.  If you use an open-collector comparator such as a 339 in the overvoltage sensing section of this circuit, you can wired-AND the comparator output with some sort of scheme to disable the circuit for a few to a few tens of milliseconds after a flash (by "pulling down" Pin 5 of the 555).   __ Designed by Don Klipstein

Downed Model Locator -  The circuit draws 1mA (!) when idle and 4 mA when buzzing.  I've been using large peizo buzzers (see part numbers below) because they are light and loud, and the 6 volt electromagnetic buzzer where weight is not so much of a concern.   __ Contact: IQ Technologies

Downed Model Locator II -  Here is another device to help you locate your downed R/C sailplane in the bushes and weeds.  Similar to the other design, this circuit plugs into a spare servo socket on your receiver, and it is a pulse omission detector.  The alarm sounds when pulses originating from your transmitter are no longer being received--turn off your transmitter to turn on the  __ Contact: IQ Technologies

Dremel drill speed controller -  The Dremel drill fitted with a mini drill-chuck on a stand is a great setup for drilling circuit boards.  The problem is that it does not do low speeds very well.  My unit had a failed internal speed controller, so I just wired around it and connected it to a regulated 24 volt DC supply.  This worked OK, but I would like a slower speed when drilling boards.  slowing down with a lower voltage, however, causes it to stall out completly when it begins drilling.  What I needed was a circuit to actually increase power to the motor under increasing load.   __ Designed by Luhan Monat-Mesa Arizona

Drill Speed Regulator -  A mini-drill machine is always needed in drilling the printed circuit board.  It is usually powered by batteries that limit the drill’s capacity.Using a power supply adaptor with a speed regulator like the one featured here can certainly improve the performance of the drill.  The speed regulator can maintain the speed of the drill no

Drill Speed Controller V2 -  PWM controller derived from a ramp generator and comparatoralso drives lamps and other devices __ Contact: P. Townshend EduTek Ltd

Drive a Complementary Output Stage & Step-Up Audio Transformer -  File contains several designs, please scroll to find this circuit.  T he following circuit uses the flasher circuit to drive a complementary output stage and step-up audio transformer.  This circuit is used in a high voltage breakdown tester but it would be useful for a variety of applications.   __ Contact: Charles Wenzel of Wenzel Associates, Inc.

Drive a LED with an Intensity Ramping Mode -  The circuit below was designed to drive a LED with an intensity ramping mode.  Two 555 timers generate two different triangle waveforms.  The upper device generates a 10KHz signal while the lower unit produces a 1Hz signal.  The two signals are fed to a . . . Hobby Circuit designed by David Johnson P.E.-December, 2007

Driving & protecting inverter IGBTs -  EDN-Design Ideas 06/12/2014     A special purpose optocoupler can solve your IGBT gate-drive and fault-feedback needs __ Circuit Design by Avago Tech Note

Driving Bipolar Stepper Motors -  Stepper motors are devices, which convert electrical impulses into discrete mechanical rotational movements.  In a typical stepper motor, power is applied to two coils.  Two stator cups formed around each of these coils,  __ Designed by Seiichi Inoue

Driving Stepper Motors -  Stepper motor are commonly used for moving robots.  If you love experimenting, stepper motors will give hours of great fun.  Learn how to generate the basic step sequences (full-step vs.  half-step), and what a full bridge driver is.   __ Designed by Projects & Ideas from Nutchip.com

DSP Musicolour Light Show; Pt.2 -  In last month's first part, we described the circuit operation of the DSP Musicolour.  In this instalment, we guide you through the construction.  The operation of the firmware and troubleshooting tips will be described next month.  In this issue there are also notes and errata for the schematic published last month.__ SiliconChip

DSP Musicolour Light Show; Pt.3 -  In last month's article, we detailed the construction of the DSP Musicolour.  In this month's article, we guide you through the final testing of the DSP Musicolour and give troubleshooting tips.  We also explain the operation of the firmware in more detail as well as discussing possible accessories.__ SiliconChip

DSP Musicolour Pt.1 -  This DSP Musicolour accepts audio input signals and drives coloured lights "in tune" with the music.  Its four output channels respond to different audio frequency bands and the brightness of the lights is in direct proportion to the amplitude of the frequency components.  A dot-matrix LED menu display is featured on the front panel and this also functions as a spectrum analyser or VU meter.__ SiliconChip

DSP Musicolour Pt.4 -  With a small and low-cost add-on PC board, the DSP Musicolour can be operated via an infrared remote controlvery handy if you want to use it in hard-to-reach places.__ SiliconChip

DSP Solution for AC Induction Motor -  Small electromechanical drives include solenoid drives, single direction DC, bi-directional DC, or brushless DC systems and are typically sized according to their frame size and power in watts.  Digital controllers, software, and complimentary analog and digital solutions from TI can help solve most drive requirements.   __ Designed by Texas Instruments App Notes, 1-Jan-96

DSPs boost Motor-control quality -  11/21/96 EDN-Design Ideas everal months after Texas Instruments (Dallas) announced its TMS320C240 DSP for motor control (EDN , Sept 12, 1996, pg 26), Analog Devices has announced its version of a motor-control DSP, the ADMC330.  These new products represent a growing trend toward designers’ using more computational power to help make both ac and dc motors more reliable, more efficient, and lower cost.  The motor-control DSPs eliminate position-, speed-, and phase-current sensors.  The DSPs also support variable-speed direct drive and, therefore, eliminate gears, belts, and hydraulics.  They also support the move to three-phase, brushless motors.   __ Circuit Design by Markus Levy, Analog Devices, Norwood, MA

DSSSEType 1 (Voltage Controlled) Solar Engine -  If you had time to experiment with the ALF type SE circuit you may have discovered some of its shortcomings with regard to a Power Smart Head adaptation. The problem is that HCMOS gates are power hungry when used as SE voltage comparators when the analog input voltage is near the CMOS switching threshold. If an HCMOS gate is used without sampling, the chip supply current can be as high as 70mA with the comparator input voltage near the trigger threshold (Vcc / 2). __ Designed by Wilf Rigter

DTMF Radio Remote Control -  Here is a circuit of a remote control unit which makes use of the radio frequency signals to control various electrical appliances.  This remote control unit has 4 channels which can be easily extended to 12.  This circuit differs from similar circuits in view of its simplicity and a totally different concept of generating the control signals __ Designed by Radioland.net

Dual Alternating Flashing Light -  This project is best for mounting on a layout to light a crossing or ring a bell.   __ Designed by ML Rollins

Dual Battery Load Sharing with Automatic Switchover of Power from Batteries to Wall Adapter -  This circuit shows a dual battery load sharing application with automatic switchover of power between the batteries and a wall adapter.  In this example, the battery with the higher voltage supplies all of the power until it has discharged to the voltage of the other battery.  Once both batteries have the same voltage, they share__ Linear Technology/Analog Devices App Note, Jul 8th 2011

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