Washing Machine Motor Controller -  Washing machines usually employ a single-phase motor.  In semi-automatic washing machines, a purely mechanical switch controls the timing and direction of the motor.  These switches are costly and wear out easily.  Here’s...__ Electronics Projects for You

Watch-Dog for Telephones -  Most of the telephone security devices available in market are simple but quite expensive.  These devices provide blinking or beeping type line-tap/misuse indications.  Quite often they do not offer guaranteed protection against unauthor-ised operation.  A very simple and uni- que circuit of a telephone watch-dog to safeguard subscriber telephone lines against any fraud is described here.  This little circuit keeps continuous watch over the telephone lines and sounds an alarm in case of any misuse.  In addition it transmits a loud tone through the telephone lines to prevent further misuse.  

Watchdog protects against loss of battery charger's control signals -  21-Jul-05 EDN-Design Ideas Hardware circuit keeps software-based charging within limits Design by Andy Fewster, Maxim Integrated Products Inc, Hampshire, UK

Watchdog timer allows entry to test Mode -  07/19/01  EDN-Design Ideas Manuals for microprocessor-based devices often include instructions for entering a "secret mode" in which you can test or reset the device.  These instructions typically ask you to depress and hold one or two switches for a minimum  Design by Greg Sutterlin and Larry Barnes, Maxim Integrated Products, Sunnyvale, CA, and Craig Gestler, Mining Safety Appliances Co, Mars, PA

Watchdog timer assumes varied roles -  02/01/01 EDN-Design Ideas The MAX6369-74 series of pin-selectable watchdog timers are designed to superviseµP activity and indicate when a system is working improperly.  During normal operation, aµP should repeatedly toggle the WDI (watchdog input) before the selected watchdog-time-out period elapses to indicate that the system is properly executing code.   Design by Terry Millward, Maxim Integrated Products, Lambourn Hungerford, UK

Watchdog Timer Reboots PC's -  06/05/97 EDN-Design Ideas When you use a PC to control a process or collect data, it's often desirable to have a watchdog timer reboot the computer if it runs astray.  The circuit in Figure 1 uses a PIC16C84.   Design by Charles Hamilton, Burr-Brown Corp, Tucson, AZ

Watchdog uses AC triggering -  08/16/01 EDN-Design Ideas A dc-triggered reset of a watchdog circuit is prone to failure.  If the watchdog program hangs up, then the reset signal becomes activated continuously, and the microprocessor has no way to escape the situation.  We found that a simple solution uses an ac trigger to reset the watchdog circuit(Figure 1) Design by Shyam Tiwari, Sensors Technology Private Ltd, Gwalior, India

Watchdog uses Leftover Gates -  08/01/96 EDN-Design Ideas The reset and µP-controlled watchdog circuit in Figure 1 a makes good use of some unused inverter gates in IC1.  The design is extremely simple.  The circuit is a continuously running oscillator with programmable high- and low-level pulse widths that have additional intervention-control input from the µP.  Because the circuit is a continuous running oscillator, the circuit generates Design by Shyam Sunder Tiwari, IGCAR, Kalpakkam, India

Water Drain Pump Controller -  A hole needs to be digged at the lowest place in the celler that have water incoming problems.  The hole is about 0.5 x 0.5 x 0.5 meter, at the bottom a large water pump is mounted.  Then the different water levels was measured, so we know how to make the sensors.   __ Designed by Thomas Scherrer OZ2CPU

Water Filling Station Controller -  This circuit was requested by a company needing a simple way to fill a large tank with water with little fuss.    They wanted a low tech method to automatically fill the tank with water without constant monitoring.    They wanted to press a single pushbutton switch and then walk away.    In their application, the water tank is first filled to a certain level.    The fixed volume of water is then slowly drained off into a second tank, where the water is mixed with another material.    The empty tank is then ready to be filled again, for another cycle. . . . Hobby Circuit designed by David Johnson P.E.-April, 2011

Water- Level Controller -  In most houses, water is first stored in an underground tank (UGT) and from there it is pumped up to the overhead tank (OHT) located on the roof.  People generally switch...__ Electronics Projects for You

Water Level Controller-Cum-Motor Protector -  Many a time we forget to switch off the motor pushing water into the overhead tank (OHT) in our households.  As a result, water keeps overflowing until we notice the overflow...__ Electronics Projects for You

Water Pump controlled by Solar Power -  A Discover Circuits visitor had a problem.  He needed a simple on/off controller for his solar powered water pump.  His system used two 12v 50 watt solar panels wired in series.  The power from the solar panels drove a submerged water pump.  However, during . . . Hobby Circuit designed by David Johnson P.E.-October, 2010

Water Pump Controller -  Here is a simple circuit for controlling water level in an overhead tank.  The main components of this pump controller are a step-down transformer, a 24V AC double-changeover relay, two floats...__ Electronics Projects for You

Water Pump Controller 2 -  A water pump controller senses the level of water in a tank and drives the water pump. The circuit described here is built around timer IC1 (555). When the water level...__ Electronics Projects for You

Water Pump Relay Control -  Water reservoir automatic level control; Simple circuitry12V supply __ Contact: Flavio Dellepiane, fladello @ tin.it

Water system controller (PDF) -  Schematic only __ Designed by Allan N. Hessenflow

Wave Multiplier for music Synthesizers -  The idea for this project came from the fabled middle section of the Serge wave multipliers.  At the time I designed this, I had never seen or heard one of these units, nor had I seen its schematic diagrams, but armed with descriptions and suppositions by various people who had seen them, and a couple of photos of CRO traces from the output of the module, I decided to design myself one. __ Designed by Ken Stone

Welch Scientific Model 2153C Stroboscope -  Here is a schematic for a typical line operated variable rate stroboscope.  This unit is from Welch ScientificModel 2153C Stroboscope.  These things typically gather dust in the dusty dark corners of high school physics labs.   __ Designed by Don Klipstein

Well Pump Controller -  Having a reliable system to pump out a sump pit is essential as mistakes and failures can lead to serious flooding and enormous expense.  In our article Sump Pump Control System we introduced a selection of electronic solutions to the following problems __ Designed by REUK-Renewable Energy UK website

Whistle Activated Switch Using Um3763 -  Surprisingly much, can turn on – shut down electric devices with a whistle sound.  This is simple sound control circuits, that different from a little common circuit is Requires high frequency noise Such as whistle sound etc.  The heart of working in this circuit is IC1 (UM3763) that is designed for this particular work.  Figure

Whistle On-Whistle Off -  This CMOS toggle flip flop circuit has an addition of2bandpass filters and condenser microphone so the relay can be toggled by whistling at it.   __ Designed by Bill Bowden

Whistle Responder -  Beeps when hears your whistle; A gadget suitable for key-holders, games etc __ Contact: Flavio Dellepiane, fladello @ tin.it

Whistler: Electronic Trainer/Coach -  This device makes it possible to generate beeps at chosen regular time intervals for timing track race training.  Each time interval is indicated by a beep, and the end of a performance test is indicated by a double beep.  Two types of test are allowedmust register on this site __ Designed by Published in Elecktor July/Aug, 2010