Electronic Circuits and electronic circuits, electronic schematics plus an extensive resource for hobbyists, inventors and engineers

DiscoverCircuits.com, has 45,000+ electronic circuits, cross-referenced
into 500+ categories.    We have searched the web to help you find quick design ideas.
We make every effort to link to original material posted by the designer. 
Please let us if you would like us to link to or post your design.

HOME Schematics Index Hobby Corner Dave's Circuits Electronic Resources Contact Info
Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches

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

Switch Circuits
Switches:  #'s - C       D - L       M - Q       R - S       T - Z


Last Updated: January 01, 2018 04:02 AM
Circuits Designed by Dave Johnson, P.E. :
Solid State 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 . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

Switch activated by Piezo Vibration -  An inexpensive piezo wafer is used to detect vibration and when the vibration is sufficient a switch is activated . . . Hobby Circuit designed by David Johnson P.E.-July, 2006

Switch Detects Audio Signal -  This circuit will activate a transistor switch when it detects at least 50mv peak to peak of an audio signal.    it could be used to turn on a relay, routing the signal to were it is needed.   . . . Circuit by David Johnson P.E.-July, 2006

Switches AC or DC power using a 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 . . . Hobby Circuit designed by David 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:

Smart Foot Switch -  Such jobs as jewel cutting and polishing require the workers to switch on/ off two electrical appliances one after another repeatedly for two different services Such jobs as jewel cutting and__ Electronics Projects for You

Smart Switch -  To switch on the mains voltage, either a mechanical switch or a relay offers a simple solution.  However, the relay and its associated components occupy a lot of space and cannot__ Electronics Projects for You

Smart switch cuts transformer turn-on current -  04/23/98 EDN Design Ideas:  NOTE: File contains multiple circuits scroll to find this circuit.   Transformer-core saturation can cause inexplicable fuse blowing, system crashes, or premature switch and relay failure.  When a core saturates, it loses its inductive characteristics; primary winding __ Circuit Design by Robert Lindsey, Hansvedt EDM, Urbana, IL

SMPSU With A Relay -  Switched mode power supply units (SMPSUs) are popular but difficult to build oneself as well problematic when it comes to understanding their design principles.  Building your own SMPSU typically requires a lot of expertise, hard to find components and time.  The circuit shown here is educational only and devised to demonstrate the principle of the__ 

Soft On/Off Switch -  Modern electronic equipment incorporate "push-to-on-push-to-off" switches that do not make noise as with old equipment.  An example of this is the power button on a ATX computer cabinet.  Here is a circuit that does the same.  it can be used to turn on/off__ 

Solid State Auto Power off on Mains Failure -  A good number of circuits which turn off the power to the load on mains failure have already appeared in EFY.  This circuit is different because it consumes no power when__ Electronics Projects for You

Solid state relay switch -  Solid State Relay Switch is a simple kit which will help you control (ON / OFF) a single high power circuit from a low power drive.  __ Designed by Rajkumar Sharma

Solid State Switch for DC-Operated Gadgets -  This solid state DC switch can be assembled using just three transistors and some passive components.  it can be used to switch on one gadget while switching off the second gadget__ Electronics Projects for You

Solid State 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 . . . Hobby Circuit designed by David Johnson P.E.-June, 2000

Solidstate Switch For Dc-Operated Gadgets -  This solid state DC switch can be assembled using just three transistors and some passive components. it can be used to switch on one gadget while switching off the second gadget__ 

Solid-State Two-Way Switch -  Two-way switches, more profoundly known as staircase switches, are widely used when a load has to be controlled from two ends of the location.  For example, a staircase lamp that needs__ Electronics Projects for You

Sound Activated Relay #1 -  This relay remains dormant until the op-amp activates upon sound via the electret-microphone.  I only tested the 2-wire type.  The input stage is a regular off-the-shelf 741 operational amplifier and connected as a non-inverting follower audio amplifier.   __ Designed by Tony van Roon  VA3AVR

Sound Activated Relay #2 -  This relay remains dormant until the op-amp activates upon sound via the electret-microphone.  Only tested with the 2-wire type.  The input stage is a regular off-the-shelf 741 operational amplifier and connected as a non-inverting follower audio amplifier __ Designed by Tony van Roon  VA3AVR

Sound Activated Switch -  This project is a sound activated switch.  Description Clap switch/Sound-activated switch designed around op-amp, flip-flop and popular 555 IC .  Switch avoids false triggering by using 2-clap sound.  Clapping sound is received by a microphone, the microphone changes the sound wave to electrical wave which is further amplified by op-amp.555 timer IC acts as mono-stable__ 

Sound Controlled Flip Flop -  Described here is a very inexpensive solution to many phono-controlled applications like remote switching on, for instance, or activating a camera, tape recorder, burglar alarms, toys, etc.  The circuit given here employs a condenser microphone as the pick-up.  A two-stage amplifier built around a quad op-amp IC LM324 offers a good gain to enable sound pick-up upto four metres.  __ 

Sound Operated Switch -  This sensitive sound operated switch can be used with a dynamic microphone insert as above, or be used with an electret (ECM) microphone. if an ECM is used then R1 (shown dotted) will need to be included. A suitable value would be between 2.2k and 10kohms. __ Contact IQ Technologies

Sound Operated Switch -  This circuit must have a 5v regulated supply.  This is provided by the 7805 regulator.  The circuit shown above should be sensitive enough to respond to a reasonably loud clap of the hands at a distance of about a metre from the microphone.  if the microphone (loudspeaker) is not very close to the circuit board, use screened lead to connect it to the rest of the circuit.  if you require greater sensitivity, you can add the simple pre-amp shown below.   __ Designed by © David Hoult

Sound Operated Switch -  This sensitive sound operated switch can be used with a dynamic microphone insert as above, or be used with an electret (ECM) m`icrophone.  if an ECM is used then R1 (shown dotted) will need to be included.  A suitable value would be between 2.2k and 10kohms.  The two BC109C transitors form an audio preamp, the gain of __ Designed by Andy Collison

SPST pushbutton switch combines power-control, user-Input functions -  28-Sep-06 EDN Design Ideas:  One control serves multiple functions __ Circuit Design by Eugene Kaplounovski, Vancouver, BC, Canada

Staircase light with auto switch-off -  This is a circuit for a staircase light that turns off the light automatically after 40 seconds, hence saving power.   __ Designed by T.A. Babu

Start-Stop Button -  The schematic diagram is similar to the one shown in our previous article, with the addition of two key (SW1 and SW2) connected to inputs iN1 and iN2.  This is all we need to test the circuit; later we can add a relay in addition to the LED, in order to drive more meaningful load - like an electric motor or a lamp __ Designed by Projects & Ideas from Nutchip.com

Stereo-amplifier IC's outputs drive multiple loads -  11/21/05  EDN Design Ideas:  Reference provide as constant bias voltage regardless of supply-voltage variations __ Circuit Design by Jean-Jacques Avenel, Maxim Integrated Products, Lesigny, France

Sun Type 5 keyboard on the PC -  Many people have dreamed of having their Sun Type 5 keyboard attached to their PC.  Now with this adapter, it is finally possible.  Because the standard Sun keyboards use TTL RS232 at 1200 bps to talk to the Suns, it's relatively easy to make them talk to any non-Sun computer by converting this to true RS232.  However PC's don't understand keyboards hooked up to serial ports without special drivers.  While such drivers do exist you will still need to keep a PC keyboard about if you want to change the BiOS setup etc __ Designed by Jonathan A. Buzzard

Switch activated by Piezo Vibration -  An inexpensive piezo wafer is used to detect vibration and when the vibration is sufficient a switch is activated . . . Hobby Circuit designed by David Johnson P.E.-July, 2006

Switch Configures Bare-Bones, Two-Digit Display -  12/21/95 EDN Design Ideas:  A project that includes a stage with three selectable gains (0.1, 1.0, and 10) requires that the rotary-gain switch also function to illuminate one of three LEDs.  These panel-mounted LEDs serve to indicate the gain in use.  This arrangement requires two switch sections—one for selecting the op amp’s gain-set resistor and one to light the corresponding indicator LED.  The circuit in Figure 1 requires only one more switch section to provide a true, two-digit, seven-section numeric LED display.  The circuit needs no active driver-decoder circuitry __ Circuit Design by Joe Wonoski, Yale University Medical School New Haven, CT

Switch Conserves Microcontroller's I/O Pin -  09/15/94 EDN Design Ideas:  The i/O pins of small, inexpensive microcontrollers are usually at a premium.  The PIC 16C54 has only one and a half ports (12 i/O pins).  Some processors have even fewer.
My application required a single-pole, six-position rotary switch for six different user selections.  The direct approach would require six µP pins, one for each selection, plus a pullup resistor for each pin. __ Circuit Design by Franklyn L Dahlberg Jr, US Air Force, Hill AFB, UT

Switch controls digital potentiometer -  02/27/02  EDN Design Ideas:  The control of electronic potentiometers in most today's applications comes from controller-generated signals.  However, a significant number of applications exist that require adjustments using manual, front-panel controls.  The circuit in Figure 1 uses one IC , one switch, and 10 discrete components __ Circuit Design by Chuck Wojslaw and Gary M Craig, Catalyst Semiconductor, Sunnyvale, CA

Switch Debouncer -  This circuit will remove the transient spikes and contact bounces from a non-latching push button switch.   __ Designed by Andy Collison

Switch Debouncer isolates input & output -  04/27/00 EDN Design Ideas:  Modern programmable-logic controllers (PLCs) for automated process-control systems have either 16 or 32 inputs and accept ac voltages of 24 to 120V.  A single circuit (a relay for isolation and an RC network with a Schmitt trigger to debounce signals to the processor) can debounce all the PLC signals in sequence.  However, this approach slows real-time data processing.   __ Circuit Design by Phill Leyva

Switch Debouncer uses only one gate -  05/30/02 EDN Design Ideas:  The circuit in Figure 1 produces a single debounced pulse each time you press S1.  Moreover, the circuit uses only logic power from the remote pull-up resistor, R2.  You can use the circuit to detect when a key is pressed in a nonenergized device, such as a device in a system that's just coming up from standby __ Circuit Design by Steven Robertson, Anritsu Co, Morgan Hill, CA

Switch Detects Audio Signal -  This circuit will activate a transistor switch when it detects at least 50mv peak to peak of an audio signal.    it could be used to turn on a relay, routing the signal to were it is needed.   . . . Circuit by David Johnson P.E.-July, 2006

Switch from Inverter to Mains Automatically -  Power a circuit directly from a power inverter, but with automatic mains power back up.   __ Designed by REUK-Renewable Energy UK website

Switch intelligently controls current -  03/30/00 EDN Design Ideas:  This circuit can intelligently control ac or dc current when connected in series with a load.   PDF contains many circuits, please scroll to find this one __ Circuit Design by Jim Hartmann, Silent Knight LLC, Maple Grove, MN

Switch Mains Powered Appliances Safely -  Find out how to safely control mains-powered devices automatically without needing an electrician.   __ Designed by REUK-Renewable Energy UK website

Switch serves dual duty in small, microprocessor-based system -  03/30/06  EDN Design Ideas:  Low-cost, easy-to-use design allows monitoring of peripherals, sensors __ Circuit Design by Steve Hageman, Windsor, CA

Switch Yields Programming Voltage for Flash µCs -  08/01/96 EDN Design Ideas:  Flash µCs are gaining in popularity because of their low cost and ease of use.  For example, Atmel's 8051-compatible mCs range from 40-pin drop-in replacements to 20-pin devices.  The problem with new flash µCs devices is the need for support tools, such as suitable flash-memory programmers.   __ Circuit Design by Dhananjay Gadre, IUCAA, Pune, India

Switched-Capacitor IC & Reference Form Elegant –48 to +10V Converter -  04/24/03  EDN Design Ideas:  A system designer must almost always face a trade-off in choosing the right part for an application.  The trade-off usually involves performance, price, and function.  An example is the issue of powering circuits from a telecom-voltage source.  Telecom systems almost exclusively use high-potential negative rails, such as -48V __ Circuit Design by Wallace Ly, National Semiconductor, Santa Clara, CA

Switcher improves overvoltage-protection -  10-Jun-04 EDN Design Ideas:  Overvoltage-protection circuits often protect electronic devices from power-supply transients, such as a rise from plugging in batteries or an external power adapter.  Although these devices traditionally find use as hysteretic switching controllers, you can reconfigure the LM3485 (Figure 1) to provide a robust overvoltage-protection circuit __ Circuit Design by Jason Rubadue, National Semiconductor, Thornton, CO

Switches AC or DC power using a 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 . . . Hobby Circuit designed by David Johnson P.E.-December, 2009

Switching (PWM) Solenoid Driver -  This is a very simple circuit to interface a current loop sensor to an input which is designed for a voltage, such as that from a standard potentiometer.  This page is technical so that interested persons can build the circuit themselves, but 4QD can also supply the interface on a 'postage stamp' sized (22mm x 27mm) board as shown in the first diagram.  it is a relatively trivial circuit!   __ Designed by Richard Torrens

Switching Current Pump Makes Better Charge -  01/16/97 EDN Design Ideas:  Many currently proposed battery-charger designs are simply voltage regulators redesigned to be current sources.  Unfortunately, this design approach is far from optimal because it leads to unnecessary hardware redundancy and complexity.  This type of charger also raises a stability problem because of the additional active device in the feedback loop __ Circuit Design by David Bell, Linear Technology App Note, Milpitas, CA

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

      <<<      This is the last page of R - S


Switches:  #'s - C       D - L       M - Q       R - S       T - Z


HOME Schematics Index Hobby Corner Dave's Circuits Electronic Resources Contact Info
Imagineering Ezine    Discover Solar Energy Dave Johnson & Associates Faraday Touch Switches


 About Us   |  Advertise on DiscoverCircuits.com   |   Report Broken Links  |    Link to DiscoverCircuits.com  |    Privacy Policy


Copyright  January, 1998 - January, 2018     David A. Johnson & Associates.  All Rights reserved. 


 Linking is ALLOWED but COPYING any content or graphics to your web site is EXPRESSLY PROHIBITED.