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Last Updated: June 02, 2021 01:44 PM

Circuits Designed by Dave Johnson, P.E.

40Khz LED Test Signal GeneratorThis 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. . . Circuit by Dave Johnson P.E.-February, 2002

40khz TV-VCR Light Source RepeaterThis circuit is designed to be placed directly in front of a standard TV or VCR remote.  The exiting light pulses produced by the circuit match the pulses from the remote but are about 10 times more powerful.  Using the device, the remote can operate a TV or VCR over three times the normal distance. . . Circuit by Dave Johnson P.E.-June, 2000

50ua Current Drives Solid State Relay Requires OnlyMost solid state relays require at least 5ma and often more input control current, to fully turn on the device.  But such current levels often force battery powered circuits to use excessively large batteries.  The relay hobby circuit shown below demands only 50uA of input current . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000

555 Timer Forms Simple Circuit PWM Motor ControllerUsing 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 David Johnson P.E.-February, 2007

5w 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 Dave Johnson P.E.-June, 2000

60 Watt Lamp with Auxiliary 14v LED LampThis circuit controls power to a standard 60 watt lamp plus generates an auxiliary 14v DC supply which can power an automotive style 12 LED array. . . Circuit by Dave Johnson P.E.-July, 2006

6V to 24V DC Day/Night SwitchUsing an inexpensive phototransistor, this circuit switches 12v to 24v power to a load, whenever the sun goes down. . . Circuit by Dave Johnson P.E.-July, 2006

9v Powered Xenon Photoflash ControllerThis 9v battery powered circuit is designed for remote control flash needs.  A charge control circuit turns off the high voltage generator when the photoflash capacitor is fully charged.  A neon lamp is included to indicate when the system is ready to flash. . . Circuit by Dave Johnson P.E.-June, 2000


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

4-channel dimmer rack -  This document describes my light dimmer project I have made.  This document is not ment to be a full construction project and it might lack some details.  The document is designed as an example those who might think to design and build their own dimmer circuit.  If you are plannign to take such project then I must warn you that you must know quite a bit of safetu issues before even thinking of building this kind of device which is connected directly to mains and controls lots of power   (mistakes might mean electrical safety and fire safety dangers).   __ Designed by Tomi Engdahl

4-Digit Keypad Controlled Switch -  Universal Keypad-Controlled Switches:  This is a Universal version of the Four-Digit Alarm Control Keypad.  I have modified the design to free up the relay contacts.  This allows the circuit to operate as a general-purpose switch.  I've used a SPCO/SPDT relaybut you can use a multi-pole relay if you wish.  __ Designed by Ron J.

4-Watt AF Amplifer -  I have recently included a page about AF amplifers for use with Homebrew rigs.  In this I mentioned that I may include a practical one-watt circuit, complete with PCB foil and layout.  Here it is, but I have taken the liberty of engineering it to provide 4-watts of AF output and with a frequency response almost suitable for Hi-Fi applications __ Designed by Harry Lythall-SM0VPO

4-way remote control uses series transmission -  01/18/01 EDN-Design Ideas A simultaneous fourway remote-control system adheres to size,  cost, and reduced-complexity   constraints and uses a series transmission to drive parallel loads  (Figure 1).  You can use.   PDF has several circuits, scroll down.    Design by JM Terrade, Clermont-Ferrand, France

5 Channel Dimmer Rack -  Note: This document describes my light dimmer project I have made.  This document is not ment to be a full construction project and it might lack some details.  The document is designed as an example those who might think to design and build their own dimmer circuit.  If you are plannign to take such project then I must warn you that you must know quite a bit of safetu issues before even thinking of building this kind of device which is connected directly to mains and controls lots of power   (mistakes might mean electrical safety and fire safety dangers).   __ Designed by Tomi Engdahl

5 channel infrared remote relays -  5 Channel Infrared   (IR) Remote is a simple kit using the famous HT12A and HT12D encoder / decoder chips from Holtek __ Designed by Rajkumar Sharma

5 Lamp/ LED Flash Driver -  General Description of the following circuit.  This circuit is based around HT–2050 manufactured by HOLTEK semiconductors.  It is a low cost, low-power C-MOS LSI designed for lamp andLED flash driver.  It requires minimum external components.  You can operate it with just two AAA cell or 3v Battery __ Designed by Holtek HT2051

5.8 watt audio power Amplifier -  A simple and very cheap audio power amplifier

50 Amp Model Motor Speed Controller-with Brake -  It fits in a tiny plastic case, can handle motor currents up to 50A and is compatible with existing radio control gear.__ SiliconChip

50ua Current Drives Solid State Relay Requires Only -  Most solid state relays require at least 5ma and often more input control current, to fully turn on the device.  But such current levels often force battery powered circuits to use excessively large batteries.  The relay hobby circuit shown below demands only 50uA of input current . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000

555 Christmas Lights -  This 555 flasher project is an exception.  This is a take-off on the previous Firefly Lights Circuit posting.  I had a strip of four tiny PCB’s remaining, so I built them up before __ Designed by Jim Keith

555 LED Flasher -  This is a small size led flasher built with the 555 timer IC that is powered from 2 x 1.5V batteries.  The circuit can be used as a flashing metronome, dark room timer, memo-reminder or other similar applications.   __ Designed by Popescu Marian

555 Pulse Width Modulator -  This circuit is capable of regulating 12V motors and DC light bulbs.  No coolrib required for Q1 or D3 if the current does not exceed 2A.  If it does, a sufficient coolrib for both the Schottky Diode (D3) and MOSFET Q1 is required __ Designed by Tony van Roon  VA3AVR

555 stepper pulse generator -  The 555 Stepper Pulse Generator kit will help you with the pulse required to drive your favorite stepper Motor driver.  This kit uses the populer 555 timer IC for generating the Stepping Pulse.  it has two range low frequency and high frequency __ Designed by © 2008, Leiterplatten Zubehör und Reflow-Kit Beta LAYOUT

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 David Johnson P.E.-February, 2007

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 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.   Design by JN Lygouras, University of Thrace, Xanthi, Greece

55V High efficiency buck-boost power manager & multi-chemistry battery charger -  EDN-Design Ideas 01/01/2016    A versatile, efficient, multi-chemistry battery charger design operates in buck & boost modes. Design by LTC Design Note

5V System Protected from ± 24V Power Supplies -  The LTC4360 overvoltage protection controller safeguards 2.5V to 5.5V systems from power supply overvoltage.  It is designed for portable devices with multiple power supply options including wall adaptors, car battery adaptors and USB ports.  The LTC4360 controls an external N-channel MOSFET in series with the input power__ Linear Technology/Analog Devices App Note, Apr 26th 2010

5V System Protected from ±24V Power Supplies & Overcurrent -  The LTC4362 monolithic overvoltage/overcurrent protector safeguards 2.5V to 5.5V systems from power supply overvoltage.  It is designed for portable devices with multiple power supply options including wall adaptors, car battery adaptors and USB ports.  The LTC4362 features a soft-shutdown controlled by the ON pin and drives__ Linear Technology/Analog Devices App Note, Jul 8th 2011

5V System Protected from 80V Overvoltage -  The LTC4360 overvoltage protection controller safeguards 2.5V to 5.5V systems from power supply overvoltage.  It is designed for portable devices with multiple power supply options including wall adaptors, car battery adaptors and USB ports.  The LTC4360 controls an external N-channel MOSFET in series with the input power__ Linear Technology/Analog Devices App Note, Apr 26th 2010

5w 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 Dave Johnson P.E.-June, 2000

60 Watt Lamp with Auxiliary 14v LED Lamp -  This circuit controls power to a standard 60 watt lamp plus generates an auxiliary 14v DC supply which can power an automotive style 12 LED array. . . Circuit by Dave Johnson P.E.-July, 2006

65V 500mA step-down converter fits automotive & industrial applications -  05/31/14  EDN-Design Ideas This switcher is happy to drop a 60V input all the way down to 0.8V.  The trend in automobiles and industrial systems is to replace mechanical functions with electronics, thus multiplying the number of microcontrollers, signal processors, sensors, and other electronic devices throughout.  The issue is that 24V truck electrical systems and industrial equipment use relatively high voltages for motors and solenoids while the microcontrollers and other electronics require much lower voltages.  As a result, there is a clear need for compact, high efficiency step-down converters that can produce very low voltages from the high input voltages Design by LTC Design Note

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 ICC08.  New s-record for 8-pin 68HC908QT2! __ Designed by Ludwig Orgler-Fachingenieur Elektrotechnik

68HC11 Synthesizes Accurate Sine Wave -  09/02/96 EDN-Design Ideas You can use a 68HC11 and a 12-bit serial DAC  (Figure 1) to generate accurate sine waves without using floating-point arithmetic.  Figure 2 shows a block diagram for this sine-wave generator.  You can easily analyze the generator's behavior by writing state equations in the z domain.  You can also write equations in the domain.  The location of the two poles Design by Mika Maaspuro, Espoo, Finland

6A Monolithic synchronous DC/DC step-down converter with digital power system management -  EDN-Design Ideas 01/02/2017    Efficient 6A buck sports PMBus configuration and monitoring Design by LTC Design Note

6-channel IR remote system with  micro PIC 16F84 -  This project is a remote control system based on a pic and an universal remote controller  for TV, named SIMPLEX.   __ Designed by Alfred73

6-Channel IR Remote Volume Control-Part 1 -  It's ideal for use with Dolby 5.1 digital decoders and lets you adjust the volume of all six channels simultaneously.__ SiliconChip

6-Channel IR Remote Volume Control-Part 2 -  It's ideal for use with Dolby 5.1 digital decoders and lets you adjust the volume of all six channels simultaneously.__ SiliconChip

6V LDO Solar Charge Controller -  This Low Dropout Voltage   (LDO) solar charge controller is a variation of the previously posted 12V LDO controller.  It is optimized for charging a 6V lead-acid battery with a 9V solar panel.  Minimum voltage drop is less than 1V.  It uses a simple differential amplifier and series P channel MOSFET linear regulator.  Voltage output __ Designed by Jim Keith

6V to 24V DC Day/Night Switch -  Using an inexpensive phototransistor, this circuit switches 12v to 24v power to a load, whenever the sun goes down. . . Circuit by Dave Johnson P.E.-July, 2006

7 band graphic eqalizer -  Audio graphic equalizers are very common as commercial products (for Hi-fi, car audio and stage use) but circuits for them are very rarely published.  I didn't design this one but it's really very simple.  The details shown are for a 7 band but the principle can be extended to almost any number of bandsif you can find accurate enough components. __ Designed by Richard Torrens

7 Channel Auto Reverse Sequential Disco Running Lights -  From 230 V AC a DC supply of + 5 V is obtained.  The power supply is given to the other blocks.  The pulse generator at a particular frequency generates the clock pulses.  The clock pulses are counted by a counter and gives output after every 10 pulses  __ Contact: IQ Technologies

76 MHz Hallogene Lamp Radio-Controlled -  This circuit is a 73 MHz Hallogene Lamp Radio-Controlled.  The purpose of it is to control the power state of a hallogene lamp by a remote control.  When we press the push botton of the remonte control, the power state of the lamp will be changed, so, if the lamp was turned on, it will turned off and if it was turned on, it will turned off.  If we press to the button another time, the same action will be occured.  When the button is pressed, a LED indicator lights on the remote control __ Designed by Serge Saati

8 Channel IR Remote Control -  Simple IR remote control with up to 8 channels!

8 Channel RF Remote Control -  This is an 8 Channel RF Remote Transmitter and Receiver that will allow to remotely control various electronic projects.  RF Remote Control provides 2 latched and 6 momentary outputs that could be used to control your favorite devices such as amplifier, robotic devices, RC cars, computer, home appliances, lamps and many other cool gadgets.  

80C31 Stepper Motor Controller -  The MD4 is a stepper motor driver design utilizing the 80C31 microcontroller.  The design is very similar to the MD-2 stepper motor driver board except that this board has an on-board +5V regulator so it does not require a dual voltage power supply to run.  It uses two Allegro UDN2540B ICs to driver the stepper motors.  The U1 is 8031AH microcontroller which can be replaced with any 80C32, 87C51, 87C52 or flash base microcontroller 89C51, 89C52 families.   __ Designed by www.wzmicro.com

80V Wide Range I2C Power Monitor Simplifies Challenging System Monitoring Tasks -  Accurate monitoring of power is an essential part of a reliable and energy efficient   (green) system design.  Measuring voltage and current of low voltage   (1.8V to 36V) supplies is straightforward, but higher voltages present additional challenges.  In this video, we will show the LTC2945 wide range I2C system monitor.  This __ Linear Technology/Analog Devices App Note, Mark Thoren Staff Scientist-Mixed Signal Products Mar 20th 2013

81-LED Chaser Light using CD4 017 -  This is a simple 81-LED chaser light using two CD4017 decade counters.  NE555 timer is used for clock generation for CD4017.  We have used only two CD4017 ICs to construct the...__ Electronics Projects for You

8-Function Remote Uses One Button, No Microcode -  12/15/09  EDN-Design Ideas Simplify the operation of a remote control Design by Jay Davis, Boeing Integrated Defense Systems, Wichita, KS

9 Volt 2 Amp PS - U -  A simple 9 Volt 2 amp supply using a single IC regulator.   __ Designed by Andy Collison

9-24Vin to 1.8VoutAT1A Low EMI uModule Power Supply -  The LTM8031 is an electromagnetic compatible   (EMC) 36V, 1A DC/DC μModule® buck converter designed to meet the radiated emissions requirements of EN55022.  Conducted emission requirements can be met by adding standard filter components.  Included in the package are the switching controller, power switches, inductor, filters and all support components.  Operating over an input voltage range of 3.6V to 36V, the LTM8031 supports an output voltage range of 0.8V to 10V, and a switching frequency range of 200kHz to 2.4MHz, each set by a single resistor.  Only the bulk input and output filter capacitors are needed to finish the design.  The low profile package   (2.82mm) enables utilization of unused space on the bottom of PC boards for high density point of load regulation.  __ Linear Technology/Analog Devices App Note, Apr 22, 2011

9v Powered Xenon Photoflash Controller -  This 9v battery powered circuit is designed for remote control flash needs.  A charge control circuit turns off the high voltage generator when the photoflash capacitor is fully charged.  A neon lamp is included to indicate when the system is ready to flash. . . Circuit by Dave Johnson P.E.-June, 2000

9V to 2A PS - U -  A simple 9 Volt 2 amp supply using a single IC regulator.   __ Designed by Andy Collison

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