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Last Updated: October 24, 2017 02:55 PM
Circuits Designed by Dave Johnson, P.E. :
Day/Night Switch-24vAC Powered -  Many low voltage outdoor lighting systems use 24vac to power the devices.  The low voltage is much safer to use outside than standard 120vac or 240vac power systems.  The circuit below is designed to turn off power to outdoor lights during daylight and turn them back on at night . . . Circuit by Dave Johnson P.E.-December, 2010

Detector/Switch for Audio Signal -  For some audio systems it is desirable to have an automatic switch circuit turn on other devices, such as an amplifier, if an audio signal is detected on one line.  The hobby circuit below will activate a transistor switch when it detects at least 50mv peak to peak of an audio signal.  The switch could be used to turn on a relay, routing the signal to where it is needed.  A single 3v lithium cell will power the electronic circuit for about 5 years . . . Hobby Circuit designed by David Johnson P.E.-July, 2006

Detects Shadow Activated Motion -  This circuit can sound an alarm when the shadow of a hand or arm moves over  two small photo diodes . . . Circuit by David A. Johnson P.E.-August, 2005

Finger Touch Activated Switch -  it does not get any easier if you want a solid state switch that is activated by the touch of a finger.  Two small metal pins route voltage through the finger skin to a MOSFET switch.  The circuit is great for situations where a membrane type mechanical switch . . . Circuit by Dave Johnson P.E.-June, 2000

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Dark Activated Switch -  This circuit will activate a relay when light falls to a preset level.  Light level can be adjusted with VR1 and the relay contacts may be used to operate an external light or buzzer.   __ Designed by Andy Collison

Dark Activated Switch-DAS1 10A/12V -  The DAS1 is a combination manual switch and automatic dark-activated switch.  it is designed to control up to 10 amps of 12V lights.  A pair of high-intensity white LEDs are included in the circuit for built-in lighting.  The circuit includes a low voltage disconnect circuit that prevents excessive battery discharge on battery operated systems.  The DAS1 is ideal for solar powered lighting systems, it can also be used for line powered and automotive/marine applications.  External 12V lights consisting of white LEDs, incandescent lamps and/or fluorescent lamps can be driven by the DAS1. __ Designed by G. Forrest Cook

Dark-Activated Switch Needs Only Three Components -  23-Jul-09 EDN Design Ideas:  Build a dark-activated switch with only a TRIAC, a photocell, and a resistor __ Circuit Design by Abel Raynus, Armitron International, Malden, MA

DAS1 10A/12V Dark Activated Switch -  The DAS1 is a combination manual switch and automatic dark-activated switch.  it is designed to control up to 10 amps of 12V lights.  A pair of high-intensity white LEDs are included in the circuit for built-in lighting.  The circuit includes a low voltage disconnect circuit that prevents excessive battery discharge on battery operated systems.  The DAS1 is ideal for solar powered lighting systems, it can also be used for line powered and automotive/marine applications.  External 12V lights consisting of white LEDs, incandescent lamps and/or fluorescent lamps can be driven by the DAS1. __ Designed by G. Forrest Cook

Data-Acquisition System Is Cheap & Simple -  12/31/69  EDN Design Ideas:  The most important criteria of a data-acquisition system for college science laboratories are simplicity and price rather than precision or speed.  The data-acquisition system in Figure 1 offers adequate precision of less than 0.5% and speed of 1 Hz to rep __ Circuit Design by Tom Lyons Fisher, Juniata College, Huntingdon, PA

Day/Night Switch-24vAC Powered -  Many low voltage outdoor lighting systems use 24vac to power the devices.  The low voltage is much safer to use outside than standard 120vac or 240vac power systems.  The circuit below is designed to turn off power to outdoor lights during daylight and turn them back on at night . . . Circuit by Dave Johnson P.E.-December, 2010

DC Motor Control using a Single Switch -  This simple circuit lets you run a DC motor in clockwise or anti-clockwise direction and stop it using a single switch.  it provides a constant voltage for proper operation of the__ Electronics Projects for You

Detector/Switch for Audio Signal -  For some audio systems it is desirable to have an automatic switch circuit turn on other devices, such as an amplifier, if an audio signal is detected on one line.  The hobby circuit below will activate a transistor switch when it detects at least 50mv peak to peak of an audio signal.  The switch could be used to turn on a relay, routing the signal to where it is needed.  A single 3v lithium cell will power the electronic circuit for about 5 years . . . Hobby Circuit designed by David Johnson P.E.-July, 2006

Detects Shadow Activated Motion -  This circuit can sound an alarm when the shadow of a hand or arm moves over  two small photo diodes . . . Circuit by David A. Johnson P.E.-August, 2005

Digital Switching System -  This circuit can control any one out of 16 devices with the help of two push-to-on switches.  An up/down counter acts as a master-controller for the system.  A visual indication in__ Electronics Projects for You

Digital Thumbwheel Switch -    NOTE: Must register on this site __ Designed by Published in Elecktor July/Aug, 2010

Digital VGA Switch -  Digital VGA switch for switching between two PC monitors with MAX465 IC .  __ 

DMX PC Keyboard Interface -  This is the Design for a DMX512 to computer keyboard interface.  it sits in line on the computer keyboard and on the DMX 512 chain.  Decoding The Lighting data and ifone it's set channels is set above 1/2 value this unit will output a sequence of keyboard keys to the connected PC.   __ Designed by Paul Harris

Doorbell Warning Switch -  This circuit will light a lamp at a remote location when the doorbell switch is pressed.  This circuit should only be used with the solenoid type doorbells, the electronic type that play tunes will not work here.  it is quite easy to miss the sound of a doorbell if you are watching TV , this__ 

Economical On/Off Power Switch -    NOTE: Must register on this site __ Designed by Published in Elecktor July/Aug, 2010

Efficiently Switches Bipolar LED -  11/22/01  EDN Design Ideas:  The circuit in Figure 1 represents one method to switch a bipolar, two-color LED using an SPDT mechanical switch or relay. This circuit wastes power and does not work properly if the power-supply voltage is not substantiallythan t __ Circuit Design by Spehro Pefhany, Trexon Inc, Toronto, ON, Canada

Eight Switcher Powers High-Performance µPs -  04/13/95 EDN Design Ideas:  The circuit in Fig 1  delivers 8A for driving as many as two of today's high-performance, high-speed µPs.  You can also optimize the design for lower current by changing a few components.  Most systems use a low-current 12V bias supply and a poorly regulated high-current 5V to power the logic.  However,  __ Circuit Design by Chester Simpson, National Semiconductor, Santa Clara, CA

Electronic Door Release -  The IC is a quad 2 input "AND" gate, a CMOS 4081.  These gates only produce a HiGH output, when BOTH the inputs are HiGH.  When the key wired to 'E' is pressed, current through R1 and D1 switchs Q5 on.  The relay energises; and Q5 is 'latched on' by R8.  Thus, the Alarm is set by pressing a single key, say one of the two non-numeric symbols __ Designed by Ron J.

Electronic Replaces Mechanical Push-Push Switch -  09/28/06 EDN Design Ideas:  Mechanical pushpushbutton switches (also known as alternate-action or push-on/push-off switches) can be bulky and expensive.  As an alternative, an electronic version uses a cheaper, NO (normally open) , momentary-on switch (Figure 1)  __ Circuit Design by Donald Schelle, Maxim Integrated Products Inc. Sunnyvale, CA

Electronic Toggle Switch -  The Project works as electronic toggle switch.  Description The circuit is based on CMOS CD4013 Flip Flop IC , The circuit has two stable states, ON and OFF.  Once it is ON, it remains ON till you press the switch again.  A short button press of a tactile switch SW1 latches the circuit ON and__ 

Electronic Toggle Switch No.1 -  Switching Circuits:  This simple circuit will energize and de-energize a relay at the push of a button.  Pushing the button once - will energize the relay.  And pushing it a second time - will de-energize the relay.  The accompanying Circuit Description offers a good introduction to the workings of the CMOS 4013. __ Designed by Ron J.

Electronic Toggle Switch No.2 -  Switching Circuits:  This is similar to the first circuit - but it is based on the CMOS 4017.  Pushing the button once - will energize the relay.  And pushing it a second time - will de-energize the relay.  The accompanying Circuit Description offers a good introduction to the workings of the 4017.  __ Designed by Ron J.

Electronic Toggle Switch No.3 -  Switching Circuits:  This circuit can be used as two entirely separate toggle switches - with each push button successively energizing and de-energizing its own relay.  Or the two switches can be interlinked with diodes - to produce a number of different switching patterns.  For example - they can be used to reverse the direction of DC motors.  __ Designed by Ron J.

Electronic Touch Switch -  Mechanical contacts have the disadvantage that they wear out.  That is why it is practical to use an electronic ‘touch switch’ in some situations.  With such a touch switch the resistance of the human skin is used for the switching action.  The schematic shows the design of a circuit that senses the resistance of the__ 

Electronic Street Light Switch -  Here’s a simple and low-cost street light switch.  This switch automatically turns on the light at sunset and turns it off at sunrise.  The automatic function saves electricity besides man-power.  Broadly, the__ Electronics Projects for You

Enhanced 4 Digit Alarm Keypad -  This is an enhanced 4 digit keypad which may be used with the Modular Alarm System __ Designed by Ron J.

Enhanced 5 Digit Alarm Keypad -  This is an enhanced 5 digit keypad which may be used with the Modular Alarm System.  This switch will suit the Modular Burglar Alarm circuit.  However, it also has other applications.  The Keypad must be the kind with a common terminal and a separate connection for each key.  On a 12-key pad, look for 13 terminals.  The matrix type with 7 terminals will NOT do.  Choose the five keys __ Designed by Andy Collison

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

Fault-latch protects switchers -  02/19/04  EDN Design Ideas:  Many power-supply designers like to have a regulator latch off in the event of an overcurrent situation or other fault condition.  Yet, many PWM controllers do not internally support this latch-off function.  Most do, however, have a __ Circuit Design by Craig Varga, National Semiconductor, Phoenix, AZ

Fighter Pilot Safety-Cover Toggle Switch -  See how an illuminated toggle switch works by breaking one open and putting it back together.  Most of these are automotive switches, which need 12 V.  The circuit schematics on the second page of the article show you how to shift voltage levels from 12 V to 5 V, and 5 V to 12 V.  A microcontroller can read the switch state and blink the LED.   __ Contact David Cook

Finger Touch Activated Switch -  it does not get any easier if you want a solid state switch that is activated by the touch of a finger.  Two small metal pins route voltage through the finger skin to a MOSFET switch.  The circuit is great for situations where a membrane type mechanical switch . . . Circuit by Dave Johnson P.E.-June, 2000

Five-Digit Alarm Control Keypad -  Alarm Control Keypads:  This Keypad is suitable for the Modular Burglar Alarm.  However, it has other applications.  Entering the First Four Digits of your chosen Five-Digit code - will energize the relay.  Entering the Full Five-Digit code - will de-energize it. __ Designed by Ron J.

Five-Digit Alarm Keypad -  This is an enhanced 5 digit keypad which may be used with the Modular Alarm System.  This switch will suit the Modular Burglar Alarm circuit.  However, it also has other applications.  The Keypad must be the kind with a common terminal and a separate connection for each key.  On a 12-key pad, look for 13 terminals.  The matrix type with 7 terminals will NOT do.  Choose the five keys __ Designed by Andy Collison

Flip on Your Car's Lights and Sirens! -  18-Jan-10 -Design News:   So you're not "HawaiI Five-O's" Steve McGarrett, but wouldn't it be cool to have flashing lights and a siren on your car? John Graham's circuit makes it all possible - if you have a Pinewood Derby car made out of wood and plastic wheels.  in John's car, coin-cell batteries power a microcontroller __  Gadget Freak-Case #156

Four Digit Keypad -  This is an enhanced 4 digit keypad which may be used with the Modular Alarm System __ Designed by Ron J.

Four-Bit µP's A/D Converter Decodes Keypad's Input -  10/13/94 EDN Design Ideas:  Fig 1 shows a MitsubishI M50927-XXXSP/FP 4-bit microcontroller decoding a 4×4 keypad using only four digital i/O lines instead of eight.  Saving four of a 4-bit µC's precious i/O lines couild be significant.4-bit µC's ADC provid __ Circuit Design by Ryoden International  Shanghai Ltd, Shanghai, China

Four-Digit Alarm Control Keypad -  Alarm Control Keypads:  This Keypad is suitable for the Modular Burglar Alarm.  However, it has other applications.  Pressing a single key will energize the relay.  Entering the Four-Digit code of your choice will de-energize it.  __ Designed by Ron J.

Four-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'veused a SPCO/SPDT relay - but you can use a multi-pole relay if you wish.  __ Designed by Ron J.

Four-Digit Keypad Controlled Switchdb -  This is a universal version of the Four-Digit Alarm Keypad.  I have modified the design to free up the relay contacts.  This allows the circuit to operate as a general-purpose switch.  it also means__ 

Frequency Switch -  This circuit is the circuit which makes the output the high level condition when the signal of the specific frequency which is is inputted.  I made this circuit in the purpose to reset the clock (adjust the minute correctly) , detecting the time signal of the radio.  I think that it is possible to apply with the variety as well as it, too.   __ Designed by Seiichi Inoue

Frequency-Activated Switch for Cars -  A cheap, adjustable design that lets you switch devices on and off according to speed.__ SiliconChip

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Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches



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