1 oscillator drives multiple solid-state relays -  16-Mar-06 EDN Design Ideas:  A conventional electromechanical relay often makes sense for switching large amounts of load current on and off and when proportional control of the load’s current or voltage is unnecessary Design by Juan Ramón Vadillo Pastor, SOR Internacional SA, Saint Quirze Del Valles, Barcelona, Spain

1 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 Design by Michael Sirkis, Radio Systems, Logan Township, NJ

12V 10A Dark Activated Switch -  The DAS1 kit can be used to automatically turn on 12V lamps when it becomes dark.  it has an on-board switch for selecting Off, Always On and On-at-Dark (Auto) operation.  The DAS1 can control up to 10 Amps of 12V DC lighting, it also includes two ultra-bright white LEDs for a low power self-contained light source.  The DAS1 is perfect for controlling external arrays of 12V white LED lamps, 12V fluorescent lamps and 12V incandescent lamps.  Use it for indoor/outdoor accent lighting, street lighting, security lights, automatic highway signs and more.   __ Designed by Solar Orbit Kit

12v-24v AC & DC Day/Night Switch -  The circuit uses a bridge rectifier circuit to convert AC into DC.  A 12v zener diode limits the operating voltage of the circuit to 12v.  A tiny Schmitt trigger inverter and a phototransistor detects the ambient light intensity.  if there is sufficient light, the inverter disables a push-pull oscillator circuit . . . Hobby Circuit designed by Dave Johnson P.E.-March, 2012

16-Way Clap-Operated Switch -  Control your home appliances without getting out of your bed.  You just have to clap in the vicinity of the microphone used in this circuit, which you can keep by the__ Electronics Projects for You

1-IC-based electronic replaces mechanical switch -  03/15/07 EDN Design Ideas:  Flip-flops debounce pushbutton switch - sample and inexpensive electronic circuit uses a low-cost pushbutton switch to toggle the electrical power on and off.  The circuit replaces a more costly and bulky push-push mechanical swit Design by Santosh Bhandarkar, Bangalore, India

1-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 Design by Israel Schleicher, Prescott Valley AZ

2 buttons provide safe start -  07/06/00 EDN Design Ideas:  The circuit in Figure 1 provide as a safety interlock that checks the actuation of two pushbuttons before enabling a relay.  When you push both buttons, the circuit actuates the relay.  At that point, you can release one of the switches without the relay' Design by Vincent Himpe, Alcatel Microelectronics, Desselgem, Belgium

2 Temperature Controlled Relays -  Switching Circuits:  These two circuits use Thermistors (Temperature Dependent Resistors).  Circuit No.1 energizes the relay when the temperature rises above a preset level. Use it to switch things on when it gets hot. Circuit No.2 energizes the relay when the temperature falls below a preset level. Use it to switch things on when it gets cold.  __ Designed by Ron J.

2 Way IR Terminal -  This unit provide 2 way IR communications using a numeric keypad and an LCD display.  Data is sent and recieved in acsiI with no regard to what the data means to any particular device __ Designed by Luhan Monat-Mesa Arizona

2 wire 4 by 4 key keyboard interface saves power -  08/17/06 EDN Design Ideas:  Resistor matrix and microcontroller encode keypad - You can use a microcontroller that includes an ADC to design a two-wire-plus-ground keyboard interface.  For example, you can use a resistive voltage divider to identify a pressed key (Reference 1).  A microcontroller's integrated ADC typically presents an input resistance on the order of hundreds of kilohms, and, for adequate accuracy, its keypad divider should comprise relatively low-value resistors of 10s of kilohms.   Design by Stefano Salvatori, University of Rome, Rome, Italy, and Gabriele Di Nucci, EngSistemi, Rome, Italy

230VAC Lamp Toggle Switch -  Compact, transformerless circuitry; No relays employed __ Contact Flavio Dellepiane, fladello @ tin.it

24 Volt Day Night Switch -  Many low voltage outdoor lighting systems use 24vac to power the devices.  The low voltage is much safer to use outside than standard 120vac or 240vac power systems.  The circuit below is designed to turn off power to outdoor lights during daylight and turn them back on at night . . . Hobby Circuit designed by David Johnson P.E.-December, 2010

240VAC Touch Switch -  This is another capacitance based touch on/touch off switch, which can control power to a 200 watt 240vac load . . . Circuit by David Johnson P.E.-July, 2006

24v NiMH Battery Charger using a 12v Solar Panel  -  A while back I received an email from a guy in the UK.  He wanted to use a small solar panel, designed to charge 12v lead acid batteries, but use it to charge a 24v battery pack.  His 24v battery pack used 20 AA size NiMH cells.  He went on to explain that his 20 cell NiMH battery pack was used very infrequently . . . Hobby Circuit designed by David Johnson P.E.-October, 2011

250kHz 1mA I Q Constant Frequency Switcher Tames Portable Systems Power -  DN108 Design Notes__ Linear Technology/Analog Devices

27MHz AM /CW Transmitter -  This site timed-out when I tried to load it.   __ Designed by Harry Lythall-SM0VPO

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