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Last Updated: November 22, 2021 02:42 PM
Circuits Designed by Dave Johnson, P.E. :

Microphone On/Off Switch Circuit is Pop Free -  This circuit uses a simple technique to eliminate the usual “pop” sound when an electret type microphone is switched on or off.  The circuit is completely passive and will work on dynamic and electret type microphones . . . Hobby Circuit designed by David Johnson P.E.-February, 2002

Momentary Operation Touch Switch -  This simple circuit uses a single IC to form a nice touch switch circuit.    A single transistor forms the remote active switch sensor.    Multiple switches can be wired in parallel.    The switch circuit can be located about 500 feet from the control circuit . . . Circuit by Dave Johnson P.E.-March, 2002

Monitor ON/OFF status of a Remote Switch -  There are many applications when a remote switch’s on/off status needs to be monitored.  Reed relay sensors, toggle control switches and security alarms contacts are just a few examples.  Routing a switch directly to a computer system hundreds of feet away . . . Hobby Circuit designed by David A. Johnson P.E.-January, 2009

Motion Alarm using piezo Device -  An inexpensive piezoelectric device is used as a motion sensing device for this motion alarm . . . Circuit by David Johnson P.E.-July, 2006

Capacitance Proximity Switch
Draws very low power - Ideal for battery-powered applications
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Links to electronic circuits, electronic schematics and designs for engineers, hobbyists, students & inventors:

Magnetic Proximity Switch -  Here is an interesting circuit for a magnetic proximity switch which can be used in various applications. The circuit, consists of a reed switch at its heart.  When a magnet is brought__ Electronics Projects for You

Mains Power Load Sensing Automatic Switch -  WARNiNG:  This circuit requires experience with mains wiring.  Do not attempt construction unless experienced and capable.  Death or serious injury may result from incorrect wiring.   __ Designed by Rod Elliott  ESP

Mains Remote Switch -  This compact design forms a remotely operated switch that receives its control signal via the mains voltage.  The switch is operated using the ‘mains remote transmitter’ described elsewhere in this issue.  With this transmitter, a switch should be connected between pins 1 and 2 of K1.  Depending on the application, this must be either a__ 

Mains Slave Switcher -  There are many situations where two or more pieces of equipment are used together and to avoid having to switch each item on separately or risk the possibility of leaving one of them on when switching the rest off, a slave switch is often used.  __ 

Mains Slave Switcher Ii -  As a guide, a one-inch reed switch with 40 turns reliably switched on with the current flowing through a 150-watt lamp (approx.625 mA) but larger reeds may require more turns.  if the master appliance draws less current (which is unlikely with power tools) more turns will be required.  The reed switch is used to__ 

Master/Slave Switch -  in this age of enlightenment any sort of relationship that could be described as master/slave would be questionable but for the purposes of this circuit it gives a good idea of how it functions.  The circuit senses mains current supplied to a ‘master’ device and switches ‘slave’ equipment on or off.  This feature is useful__ 

Measuring Jitter in Digital Systems an 1448-1 -  Application Note__ Aligent

Method provides automatic machine shutdown -  27-May-04 EDN Design Ideas:  Some machines need to run for long periods and therefore may finish their work in the middle of the night or during the weekend.  For the time remaining, until the operator returns, the machines stay idle, uselessly consuming power.  This design idea allows a machine to completely shut itself down after finishing its work Design by Jean-Bernard Guiot, Mulhouse, France

Microcontroller Clapper Switch -  introduction I always thought the clapper so cool.  For those who are lazy like me, turn on or off the bedroom light without getting out of bed, simple clap your hands is amazing.  Thinking about it I projected one for me.  Several __ Designed by Toddy Cangica

Microcontroller multiplexes DIP switches to I/O port -  02/17/00 EDN Design Ideas:  At times, aµC must read a large number of DiP switches, such as for system identification, bus-address setup, manual configuration, or other purposes.  However, the available number of i/O lines is sometimes not enough to assign a switch to each one.    __ Circuit Design by Gregory Willson

Microphone On/Off Switch Circuit is Pop Free -  This circuit uses a simple technique to eliminate the usual “pop” sound when an electret type microphone is switched on or off.  The circuit is completely passive and will work on dynamic and electret type microphones . . . Hobby Circuit designed by David Johnson P.E.-February, 2002

Momentary Operation Touch Switch -  This simple circuit uses a single IC to form a nice touch switch circuit.    A single transistor forms the remote active switch sensor.    Multiple switches can be wired in parallel.    The switch circuit can be located about 500 feet from the control circuit . . . Circuit by Dave Johnson P.E.-March, 2002

Momentary switch controls mains with latch-on & remote shutdown -  12/30/13  EDN Design Ideas:  Convert a momentary switch into one that latches as well as protects loads from rapid cycling - The purpose of this Design idea was to improve reliability, add new features, and replace a latching power switch with a momentary one Design by Peter Demchenko

Momentary Switch Teamed With Latching Relay -  This circuit allows an SPST momentary pushbutton to act as a push-on push-off switch, using a DPDT latching (bi-stable) relay.  it was originally intended to allow a single pushbutton switch on the dash of a vintage car to provide a latched function.  The relay only draws current when it is being switched.  At other times, __ 

Momentary Switch with 555 -  Based on NE555 this circuit turns on and off the IC output by a momentary switch.  in other words it works as a mechanical latching relay, but the circuit backs to the start condition when you switch off the power supply.  This feature is often required in automotive devices.  No relay contacts are used, infact I connected the __ Designed by Andrea De Napoli

Monitor ON/OFF status of a Remote Switch -  There are many applications when a remote switch’s on/off status needs to be monitored.  Reed relay sensors, toggle control switches and security alarms contacts are just a few examples.  Routing a switch directly to a computer system hundreds of feet away . . . Hobby Circuit designed by David A. Johnson P.E.-January, 2009

MOSFET Pair makes Simple Circuit SPDT Switch -  12/09/99 EDN Design Ideas:  ith an n-and p-channel MOSFET, you can easily implement a single-pole double-throw (SPDT) switch to isolate part of a circuit and power it from a secondary supplyPDF has several circuits, scroll for this one.    Design by Howard Chen, Vishay Siliconix, Santa Clara, CA

MOSFET Replaces Switch -  02/03/94 EDN Design Ideas:  By using a cheap, readily available MOSFET, you can use a single-pole switch to turn a bipolar power supply on and off without consuming extra power.  in Fig 1, the switch simply controls the MOSFET gate, which switches on the negative supply.  Resistor R, which can be several Design by Malcolm Watts, Wellington Polytechnic, Wellington, New Zealand

MOSFET switch provides efficient AC/DC conversion -  02/17/00 EDN Design Ideas:  Occasionally, you have access to a transformer for powering a dc circuit, but its output voltage is much higher than that required for the dc voltage.  The full-wave-rectified and filtered output of an ac input voltage V X , is V DC =1.414V X-2V F , where V F is the forward drop in the rectifier (approximately 0.7V).    Design by Spehro Pephany, Trexon Inc, Toronto, ON, Canada - February 17, 2000

MOSFETs Reduce Crosstalk Effects On Analog Switches -  02/17/97 EDN Design Ideas:  Some cost-effective analog multiplexer/demultiplexer IC s, such as the CD4053 and CD4066, find frequent use as signal distributors.  These digitally controlled analog switches have low on-resistance.  However, with all channels in the same package, crosstalk can be annoying and unavoidable.  Figure 1 provide as a cost-effective and viable method of solving this problem.  By simply adding some n-channel MOSFETs, such as the 2N7002 or 2N7000, the crosstalk effect becomes negligible.  When the Channel Select signal is high, the CD4053's input pins A, B, and C assume a level of nearly 0V.   Design by Stanley Chen, Global Mixed-Mode Technology, Taipei, Taiwan

Motion Alarm using piezo Device -  An inexpensive piezoelectric device is used as a motion sensing device for this motion alarm . . . Circuit by David Johnson P.E.-July, 2006

Motion Sensor Light Switch -  3-Sep-15 -Design News:   Are there light switches in your home that aren't as conveniently located as you would like? This laser-based switch decoder and driver allows for flexible control of those lights located in less than ideal places.  I live in an apartment.  My kitchen is boring and can be accessed from either end of __  Gadget Freak-Case #272

Multiple Switches with Single PIC Input -  There are many techniques to implement multiple switches into PIC  microcontroller.  This technique requires only one ADC pin to detect voltage level when each switch for each state is pressed and each switch is associated with a voltage.  For example : if we need to connect 16 switches with 10 bit PIC .  __ 

Multi-Position Mains Switch -  The circuit shown here was born out of necessity after one of our colleagues had just renovated his kitchen and realized afterwards that there were not enough switches.  Obviously he was not too keen to partially demolish the kitchen to install a few additional wires in the already tiled wall.  That’s how the idea arose__ 

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Got Designs?
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