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Last Updated: January 01, 2018 04:02 AM
Circuits Designed by Dave Johnson, P.E. :
On/Off Latch Circuit -  Often you want to turn on and off power to a device with a single pushbutton switch.  The circuit below performs this logic function with just a few parts and can operate from DC supplies between +3v to about 15v.  it uses two inverters within a 74C14 or a CD4069 hex inverter package.  Each press of the button toggles between the two on/off logic states.   . . . Circuit by David Johnson P.E.-January, 2010

On/off Pushbutton Switch with 30 Minute Timeout -  I received an email from a Discover Circuits visitor.  He wanted to control power to a LED camping light he was building.  He wanted to turn the light on and off with a small pushbutton switch.  He also wanted a timer so the light would not stay on longer than 30 minutes at a time.  it seems that his kids often turned lights on when going to bed and then forgot to turn them off . . . Circuit by Dave Johnson P.E.-January, 2012

On/Off Switch with Latching Relay -  The circuit below switches AC or DC power to a load using an ultra low power 3v latching relay with two coils.  The relay can handle about 10 amps of current, up to 250vac.  Each time the small pushbutton is pressed, the circuit either latches the relay . . . Circuit by David A. Johnson P.E.-December, 2009

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
6 Models Available - Call 806-368-7747




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

Negative Voltage Load Switch -  The good thing about this design is that I can make use of the system i/o voltage to control the on/off and this is the whole idea.  However, there are many many type of load switches that turn of negative voltages.   __ Designed by Nicholas Choong

Nonvolatile Standby/On Switch Remembers Its State -  09/03/09  EDN Design Ideas:  Remember your circuit's state when the power goes out __ Circuit Design by Anatoly Andrusevich, Maxim Integrated Products Inc, Moscow

Novel Idea Implements Low-Cost Keyboard -  3-Apr-03 EDN Design Ideas:  Many applications that use a microcontroller also use a keyboard.  if your application uses a relatively powerful microcontroller, you can use several free i/O pins or an unused input with an ADC to effect an easy keyboard connection.  But, if the microcontroller in your system has too few free i/O pins and no on-chip ADC, you can be in trouble __ Circuit Design by Jean-Jacques Thevenin, Thomson Plasma, Moirans, France

On And Off Button -  in this simple circuit we give the chip a little more attention than usual.  it is astonishing what can be built with a 555.  We are always infatuated with simple circuits using this IC , such as the one shown here.  The 555 is used here so that a single push-button can operate a relay.  if__ 

On and Off Programmable Controller for 3-Phase Motor -  Automatic on/off controller for a 3-phase electric motor can be made with a programmable time switch.  in this case a maximum of eight time durations can be programmed.  The system has two__ Electronics Projects for You

ON OFF Touch Switch with 555 -  This ON OFF touch switch circuit is based on the well known timer IC 555 (IC 1) , which drives a relay that acts like a switch.  The metal surfaces can have what form we want, but it should be clean and very close to the circuit.   __ Designed by Popescu Marian

On/off buffer switches analog or digital signals -  30-Mar-06 EDN Design Ideas:  Use an op amp and a dual SPST to switch signals under digital control __ Circuit Design by Liviu Pascu, Kepco, Flushing, NY

On/Off Latch Circuit -  Often you want to turn on and off power to a device with a single pushbutton switch.  The circuit below performs this logic function with just a few parts and can operate from DC supplies between +3v to about 15v.  it uses two inverters within a 74C14 or a CD4069 hex inverter package.  Each press of the button toggles between the two on/off logic states.   . . . Circuit by David Johnson P.E.-January, 2010

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

On/off Pushbutton Switch with 30 Minute Timeout -  I received an email from a Discover Circuits visitor.  He wanted to control power to a LED camping light he was building.  He wanted to turn the light on and off with a small pushbutton switch.  He also wanted a timer so the light would not stay on longer than 30 minutes at a time.  it seems that his kids often turned lights on when going to bed and then forgot to turn them off . . . Circuit by Dave Johnson P.E.-January, 2012

On/Off Switch with Latching Relay -  The circuit below switches AC or DC power to a load using an ultra low power 3v latching relay with two coils.  The relay can handle about 10 amps of current, up to 250vac.  Each time the small pushbutton is pressed, the circuit either latches the relay . . . Circuit by David A. Johnson P.E.-December, 2009

ON/OFF with MicroControllers -  Here is a technique how to implement an ON/OFF button using microcontrollers.   __ Designed by Jose Pino

One Button Digital On-Off Switch -  The load is driven by the MOSFET iRFZ44 and 4093 AND gates are used in the circuit.  The output of the 4093 IC drives the MOSFET.  Only one button allows you to change the on-off state of the electronic circuits in which you use this switch.  The circuit schematics is above.  Click image to see the larger schematics diagram.  __ 

One Button On-Off Switch with 4093 & IRFZ44 -  The load is driven by the MOSFET iRFZ44 and 4093 AND gates are used in the circuit.  The output of the 4093 IC drives the MOSFET.  Only one button allows you to change the on-off state of the electronic circuits in which you use this switch.  The circuit schematics is above.  Click image to see the larger schematics diagram.  __ 

One processor pin controls on/off function -  04/29/04  EDN Design Ideas:  A recent Design ideas - prompted me to offer the simpler solution that I used in a recent project (Reference 1].  We needed a momentary power switch with processor supervision.  This supervision would allow the processor to delay a powe __ Circuit Design by Michael Sirkis, Radio Systems, Logan Township, NJ

One switch controls digital potentiometer -  09/19/02  EDN Design Ideas:  This design idea     is an evolution and simplification of another (Figure 1, Reference 1].  Replacing the three inverted-input NOR gates with their logical equivalents, positive-input NAND gates, makes these three gate symbols consistent __ Circuit Design by Jim Bach, Delphi Delco Electronics Systems, Kokomo, IN

One switch selects one of three signals -  03/02/06  EDN Design Ideas:  Total cost is less than $1 - Low-cost, easy-to-use design allows monitoring of peripherals, sensors.   __ Circuit Design by Felix Matro, JL Audio Corp, Phoenix, AZ

One-wire keypad interface frees microcontroller-I/O pins -  03/31/05  EDN Design Ideas:  Using this interface topology, you can reduce the number of keypad interface wires to just one and thus save critical microcontroller i/O ports __ Circuit Design by Israel Schleicher, Prescott Valley AZ

On-Off Temperature Control -  This circuit controls a load (in this case a dc brushless fan) based on a temperature compared with a setpoint. THe transduced is a diode in the forward polarization regime. in fact when forward biased, the forward voltage drop accross a diode has a temperature dependance, in particular has a negative linear (ish) slope __ Contact Jonathan Filippi

Opamp Design & Test Board -  Quickly assemble an OpAmp circuit for testing.    Very easy and intuitive to use __ Designed by Rod Elliott  ESP

Optical Remote On/Off Switch -  First published on: 1-10-2006 Using this optical remote control, you can switch on/off any electrical or electronic load.  Like any remote control system, it has a minI transmitter unit (Fig.1) and__ Electronics Projects for You

Optical Toggle Switch using a Single Chip -  Using dual flip-flop IC CD4027 employ a 555 based monostable circuit to supply input clock pulses.  The circuit described here obviates this requirement.  One of the two flip-flops within IC CD4027 itself acts as square wave shaper__ 

Got Designs?
Please eMail
if you want me to link to and/or post your original design Thanks.

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