Small Pushbutton Controls 10 Amps AC -  The circuit below uses a pair of long lasting lithium coil cell batteries to power a latching relay circuit. With each activation of the small pushbutton, the relay is either latched closed or unlatched open. Since coin cells can’t provide the necessary peak current, a 500uF capacitor is used to store the needed energy. The circuit standby current is kept very low by using a stack of five 100uF ceramic capacitors instead of the usual electrolytic cap . . . [Circuit by David Johnson P.E.,  01/20/12]

Smart Exhaust Fan Switch -  Exhaust fans in washrooms can be connected to the lighting circuit so that these switch on and switch off with the electric light. . . .  [© EFY Enterprises Pvt. Ltd. All rights reserved]

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 ser. . .  [Circuit by JAYAN A.R]

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 be accommodated in a standard switch box. The smart switch circuit, shown here, offers a better alternative. It is nothing but an on/off controller and uses an electronic circuit that behaves like a normal switch. A flat pushbutton control provides an aesthetic look to your switch panel. . . .  [© EFY Enterprises Pvt. Ltd. All rights reserved]

Smart switch cuts transformer turn-on current -  04/23/98 EDN Design Idea   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 File contains multiple circuits. . .  [by Robert Lindsey, Hansvedt EDM, Urbana, IL]

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. . . 

Solenoid trip circuit works at battery's end of life -  07/08/04  EDN Design Idea   This Design Idea  involves a low-power motion-detector circuit that operates from battery power for extended times. Part of the design includes a solenoid-operated trip mechanism that triggers whenever it detects motion. . . .  [by Brad Peeters, Theta Engineering, Costa Mesa, CA]

Solid state relay switch -  . . .  [by IQ Technologies Industry, unless otherwise noted online]

Solid State Reversing Circuit -  This circuit uses solid state switching (transistors) to control direction of a DC motor. You have precise control of the movement of the motor, and an indication of direction provided by LEDs. . . .  [Andy Collison]

Solid State Switch for DC Operated Gadgets -  . . . 

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.,  06/03/00]

Solidstate Auto Power off on Mains Failure -  This is a circuit that switches off the supply to electrical appliances when there is any failure in power supply. It is based on transistors and triac and doesn't draw any power when the load is off. . . .  [© EFY Enterprises Pvt. Ltd. All rights reserved]

Solid-State Relay Saves Battery's Life -  09/01/94 EDN Design Idea   The circuit in Fig 1 uses a low-resistance p-channel FET, Q4, to disconnect a load from the battery when the battery's voltage drops below a certain value. After you disconnect the circuit, it remains off until you remove and rep. . .  [by Tom Gay, Siemens, Regensburg, Germany]

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. . . .  [© EFY Enterprises Pvt. Ltd. All rights reserved]

Sound Activated Toy  -  This circuit makes a flower bop to the beat of music. The flower stem contains a crooked wire which is spun by the motor. The circuit is a microphone driven peak-detecting one-shot and works very well. The microphone is in a sponge mount to insulate it from the vibration of the running motor. Similar circuits are used to drive rock'n coke cans. . .  [Reverse engineered schematic by Stepan Novotill]

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. . . .  [© David Hoult 2013]

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. . .  [Andy Collison]

Sound triggered flash -  If you wish to take a picture of a fleeting event which generates a sound, you can do it with this sound activated trigger. It does not require any power supply: it feeds on the high voltage available on the flash trigger terminal. Any economic ceramic microphone is suitable for the purpose. . . 

Sound Triggered Night Light -  A while back, I received a schematic from a guy by the name of Karl. He described a situation he and his wife found themselves in aboard a cruise ship in the Caribbean. They were staying in a room toward the inside of the ship, which did not have any port holes, windows or a balcony . . . [Circuit by Dave Johnson P.E.,  08/04/13]

S-Parameters Allow High-Frequency Verification of RF Switch Models -  Analog Devices-Analog Dialogue. . .  [by Creech, Joeseph]

SPST pushbutton switch combines power-control, user-input functions -  09/28/06  EDN Design Idea   One control serves multiple functions. . .  [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. . . .  [© EFY Enterprises Pvt. Ltd. All rights reserved]

Stall-Motor Switch Machine Power Supplies -  switch machine control circuit for model trains. . .  [Designed by Rob Paisley]

START-STOP Buttons  -  A SHORT COURSE in three designs to learn how to use Nutchips from ground up. You will start making LED flashes. You will continue learning how to switch outputs with separate START and STOP buttons. In the last instalment, you will learn how to remotely switch a light on and off. . . .  [Projects & Ideas from Nutchip.com]

Stereo-amplifier IC's outputs drive multiple loads -  11/21/05  EDN Design Idea   Reference provides constant bias voltage regardless of supply-voltage variations. . .  [by Jean-Jacques Avenel, Maxim Integrated Products, Lesigny, France]

Stop Light Switch Circuit -  When the brake pedal is on depressed, battery positive voltage normally applies through the STOP fuse and stop light switch to terminal STP– of the ECU, and the ECU turns the cruise control off. . . . 

Strobe Trigger -  These pictures are scenes frozen by a flash unit that is triggered by the action being recorded. They were made by setting up a shot, opening the camera shutter using its "bulb" setting, and carrying out some action that opened or closed a circuit to trigger the flash. The balloon pictures were taken by triggering the flash when the balloon began to shrink after being popped. In most cases the balloon had a strip of foil attached to it with probes pressed against it on two sides, with a circuit interrupted when the foil pulled away from the probes. . .  [John DuBois designer]

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. . .  [Jonathan A. Buzzard]

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