Safe Universal Mains Switching Box (Silicon Chip magazine, May 2006)  -  I (Bob Barker) didn't design this. Bill De Rose (ex Dick Smith Electronics Kits Dept) came up with this brilliantly simple project which allows any low voltage switch or switching circuit to safely control any 240V mains-powered appliance up to 10A. The uses are nearly endless. . . .  [designed by Bill De Rose]

Safety Light -  My 1200 square foot metal shop only has one small entrance door and no skylights. If the lights are turn off while inside, there is not enough light to safely find the door to exit the building. On a couple occasions, while I was quietly working at my test bench, my wife would walk into the shop, grab a garden tool and rush back out, turning off the lights and closing the door without thinking . . . [Hobby Circuit designed by David A. Johnson P.E.,  11/29/04]

SB-100: Subscriber Line Card for Central Office Telephone Switching Equipment -  Application Note. . .  [National Semiconductor]

Scalable latch requires no capacitors or clock -  08/19/04  EDN Design Idea   Circuits that latch one-of-N switches usually use a digital approach. Such circuits are often useful in human-interface situations, such as audio-mixing consoles, video-feed selection, or current-loop-control redundancy systems. In. . .  [by Robert Most, Dow Corning S&T Electronics, Midland, MI]

Scanmate Audio Activated Recorded -  Add this easy project to your regular scanner or DX'ing apparatus and never miss action again. Or use this system to check a range of frequencies for band activity when you're not there. I use it to check a range of 'secret' frequencies overnight when I'm sleeping. Works for me. . .  [Tony van Roon's circuit]

Scheme Improves On Low-Cost Keyboard -  10/30/03  EDN Design Idea   You can easily improve on a previous Design Idea   to produce a slightly simpler resistor arrangement with better timing balance between switches, using a single resistor value (Reference 1, Figure 1]. . . .  [by Martin O'Hara, Telematica Systems Ltd, Cranfield, Bedfordshire, UK]

Security Circuit Eschews Sophistication -  05/26/94 EDN Design Idea   Because of the many states involved in implementing sequential combination locks, most designers use a microcontroller or a PLD. But for those die-hard discrete designers who don't want to bother with debugging programs, here's a. . .  [by Cheng Chen, AEG, Ajax, ON, Canada]

Security System Switcher -  The circuit described here allows the security system to automatic in on state. It uses a transducer to detect intruders and a 5V regulated DC power supply provides power to the circuit. . . .  [© EFY Enterprises Pvt. Ltd. All rights reserved]

Sensitive Temperature Switch -  This is a circuit for a highly sensitive temperature switch that sets off an alarm whenever there is a sharp rise in the temperature. . . .  [© EFY Enterprises Pvt. Ltd. All rights reserved]

Sequential state machine aids in automatic control -  09/02/04  EDN Design Idea   Creating a sequential state machine is a common approach for automatic-control design. The meth-od finds wide use for controlling sequential processes in industry, robotics, and measuring. The concept of a state machine is simple A. . .  [by Abel Raynus, Armatron International, Malden, MA]

Ser-Key 10-Key Serial Keypad Encoder -  Schematic only, no circuit description. . .  [Reynold's Elec]

Service Request Beeper -  A single press of a pushbutton switch turns on a beeper for one second but can’t be activated again for 60 seconds.  . . . [Hobby Circuit designed by Dave Johnson P.E.,  09/25/05]

Set Your Lights to Music -  08/06/09  EDN Design Idea   This circuit activates six ac outlets according in a logarithmic thermometer-code format, causing six to 12 strings of lights to flash on and off according to the level and tempo of music you are playing. . .  [by Hanif Saeed, Maxim Integrated Products, Inc, Sunnyvale, CA]

Shadow Activated Motion Detector -  The hobby circuit below works quite well in typical indoor room lighting. I would not recommend its use in direct sunlight. Two small PIN photodiodes positioned about one inch apart form a shadow detector. With no shadow cast on the devices, both device . . . [Hobby Circuit designed by Dave Johnson P.E.,  08/21/05]

Shop Safety Light -  My 1200 square foot metal shop only has one small entrance door and no skylights. If the lights are turn off while inside, there is not enough light to safely find the door to exit the building. On a couple occasions, while I was quietly working at my test bench, my wife would walk into the shop, grab a garden tool and rush back out, turning off the lights and closing the door without thinking . . . [Hobby Circuit designed by David Johnson P.E.,  11/29/04]

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