Quickly discharge power-supply capacitors -  07/05/01  EDN Design Idea   A perennial challenge in power-supply design is the safe and speedy discharge, or "dump," at turn-off of the large amount of energy stored in the post rectification filter capacitors. This energy, CV2/2, can usually reach tens of jo. . .  [by Stephen Woodward, University of North Carolina, Chapel Hill, NC]

Radio Controlled 3way Light Switch  -  TRIAC based 3 way light switches are very uncommon. Typical circuit representative of those used in most light switch type digital timers. The timer module is normally a PIC or custom chip, and it syncs to the AC line so that a trigger pulse can be supplied at the right moment. . .  [Reverse engineered schematic by Stepan Novotill]

Ramping Lamp Driver -  This circuit drives any 12v lamp, incandescent or LED type, in a ramping fashion. Each press of the button toggles the lamp from a fully off mode to a fully on mode. But, instead of an instantaneous lamp intensity change, the power is slowly ramped up a . . . [Hobby Circuit designed by Dave Johnson P.E.,  12/21/07]

Ramping LED Driver -  The circuit below was designed to drive a LED with an intensity ramping mode. Two 555 timers generate two different triangle waveforms. The upper device generates a 10KHz signal while the lower unit produces a 1Hz signal. The two signals are fed to a . . . [Circuit by Dave Johnson P.E.,  12/21/07]

RC Receiver Hosts Two Independent Switches -  06/06/96  EDN Design Idea   Typical inexpensive radio-control (RC] systems have servo-motor outputs, but no on/off switch outputs. You can add two independent RC switches to a system without making any transmitter or receiver modifications. . .  [by Tom Howell, US Army ARDEC, Picatinny Arsenal, Dover, NJ]

Receiver Circuit-Ultrasonic Switch -  The circuit described generates (transmits) ultrasonic sound of frequency between 40 and 50 kHz. As with any other remote control system this cirucit comprises of a mini transmitter and a receiver circuit. Transmitter generates ultrasonic sound and the receiver senses ultrasonic sound from the transmitter and switches on a relay. . .  [Andy Wilson's site]

Reduced Power Sequential LED Flasher -  The 74HC4017 is a neat decade counter which has 10 decoded outputs. When supplied with a low frequency clock and with a LED attached to each of the outputs, an interesting ten step sequential flasher effect can be produced. The LEDs can be configured in . . . [Hobby Circuit designed by David A. Johnson P.E.,  11/30/08]

Reed Switches -  Find out more about reed switches and their uses in RE. . . .  [REUK-Renewable Energy UK website]

Reflected Infrared Light Switch -  Infrared light reflected off a finger is used to activate this switch circuit. Drawing only 30uA from a 3v supply, this circuit will detect a human finger with a range of about 1 inch. The sensor uses an inexpensive infrared LED and a matching photo diode . . . [Hobby Circuit designed by David Johnson P.E.,  07/09/06]

Relay driver saves substantial power -  07/02/98 EDN Design Idea   (File has several circuits, please scroll to find this one. )It is common practice to operate relays and solenoids at a reduced holding power once the mechanical actuation takes place. Relays are usually specified to pull in wit. . .  [by Tim Herklots, Maxim Integrated Products, Southamption, UK]

Relay Driver Switches Two Relays With One Pin -  03/03/11  EDN Design Idea   Logic 1, logic 0, and high-Z make for three possible states: forward, reverse, and off. . .  [by Gunther Kraut, PhD, Egmating, Germany]

Relay Toggle Circuit Using a 555 Timer -  This is probably the best toggle circuit. . . .  [William Bowden's site]

Relay Toggle Circuit using a Dual 555 timer 556: This is probably the best toggle circuit. -  This toggle circuit operates by using a couple 555 timers wired as inverters. Pins 2 and 6 are the threshold and trigger inputs to the first timer and pin 5 is the output. The output at pin 5 will always be the inverse of the input at pins 2 and 6. Likewise, the output at pin 9 of the second timer will always be the inverse of the input at pins 8 and 12. A 100K resistor connects the output of one inverter to the input of the other so the state of one will be the opposite of the other. . . .  [William Bowden's site]

Relay Toggle Circuit Using a MOSFET and Push Button -  . . .  [Bill Bowden, designer]

Relay Toggle Circuit using a Single Transistor & Push Button -  This toggle circuit operates by using a couple 555 timers wired as inverters. Pins 2 and 6 are the threshold and trigger inputs to the first timer and pin 5 is the output. The output at pin 5 will always be the inverse of the input at pins 2 and 6. Likewise, the output at pin 9 of the second timer will always be the inverse of the input at pins 8 and 12. A 100K resistor connects the output of one inverter to the input of the other so the state of one will be the opposite of the other. . . .  [William Bowden's site]

Remote control turns battery on and off -  09/12/97 EDN Design Idea   The circuit in Figure 1 acts as a latching solid-state relay. A short application of a magnetic field in the vicinity of S1 toggles the relay on and off. The relay switches power from a 3V battery at load currents as high as 10 m. . .  [by Allen Harstine,Integrated Measurement Systems Inc, Beaverton, OR]

Remote Doorbell Warning Switch -  This circuit should only be used with the solenoid type chime doorbells, the electronic type that play tunes will not work here. The hardest part for this circuit was the title. It is quite easy to miss the sound of a doorbell if you are watching TV , this circuit gets round the problem by providing a visual indication, i. e. a lamp. . .  [by Andy Collison]

Remote IR Terminal -  This unit provide 2 way IR communications using a numeric keypad and an LCD display. Data is sent and received in ASCII with no regard to what the data means to any particular device.
. . .  [Luhan Monat - Mesa Arizona]

Remote Switch Uses No-Power Fiber-Optic Link -  10/10/96 EDN Design Idea   The heavy-duty switching device in Figure 1 counts the number of products manufactured and rolled out of a production line per hour. The switch is useful for counting rolling heavy objects or materials weighing one to several. . .  [by Shyam Tiwari, IGKAR, Kalpakkam, India]

Remove Relay-Contact Bounce -  11/27/03  EDN Design Idea   Advances in semiconductor technology have allowed ICs to replace many mechanical relays, but relays still dominate in high-current circuits that must stand off high voltages of arbitrary polarity. Contact bounce in those relays, ho. . .  [by John Guy, Maxim Integrated Products, Sunnyvale, CA]

Removes Relay-Contact Bounce -  11/27/03  EDN Design Idea   Advances in semiconductor technology have allowed ICs to replace many mechanical relays, but relays still dominate in high-current circuits that must stand off high voltages of arbitrary polarity. Contact bounce in those relays, ho. . .  [by John Guy, Maxim Integrated Products, Sunnyvale, CA]

Replace a Pushbutton Switch with this Infrared Safety Switch -  Using a slotted optical sensor, this circuit can be used as a replacement for a large mushroom pushbutton safety switch . . . [Hobby Circuit designed by David Johnson P.E.,  07/11/06]

Replace a rotary switch with a potentiometer -  04/07/14  EDN Design Idea   Why use an expensive rotary switch with your microcontroller when you can use a cheap pot instead? Microcontroller-based products sometimes require rotary switches. As many microcontrollers have an onboard ADC, it is easy to replace the rotary switch with a low cost potentiometer, when a rotary switch is too expensive or unavailable . . .  [by Claude Haridge]

Reversing Loop Switch Machine Controller (PCB)    (Tortoise® Type Machines) -  switch machine control circuit for model trains. . .  [Designed by Rob Paisley]

RF 2.45Ghz Signal Detector -  This passive RF indicator is made from a few simple parts. A 100uA moving coil meter is used to display the relative intensity of the RF signal. This circuit can be used with some cell phones and many cordless telephones . . . [Hobby Circuit designed by David A. Johnson P.E.,  07/09/06]

RF SPDT switch IC takes you to 3 GHz -  04/23/04  EDN Product Brief   The PE4259 from Peregrine Semiconductor gives you SPDT switching from dc to 3 GHz, along with requisite control logic and a low-voltage interface. The PE4259 from Peregrine Semiconductor gives you SPDT switching from dc to 3 GHz, along with requisite control logic and a low-voltage interface (Picture). Using a CMOS silicon-on-sapphire technology, the device has 0. 3-dB insertion loss at 1 GHz and 0. 45 dB at 2 GHz, high third-order intercept point of 60 dBm at 2 GHz, and isolation of 32 dB at 1 GHz. It operates from a 2. 3 to 3V supply and offers 2-kV human-body-model ESD tolerance; the SC70-package device sells for 29 cents (25, 000). . .  [by Bill Schweber]

Route Control for Stall-Motor Switch Machines -  This page shows some methods of track routing control for Stall-Motor type switch machines. The principle method uses a 2 Pole Multi Position rotary switch while an alternate uses optoisolators and transistors to select the routes. . . .  [from Rob Paisley's Model Train web site]

Route Control for Stall-Motor Switch Machines  -  switch machine control circuit for model trains. . .  [Designed by Rob Paisley]

RS-232 DB-9 Switch-to-Flip between Two Serial Ports -  . . .  [Wichit Sirichote, designer]

RS-232C port scans remote keypad -  12/04/97 EDN Design Idea   In many embedded or control applications, you might prefer to use a small, customized keypad with your PC-based system rather than a full-fledged alphanumeric keyboard. You may also need to locate the keypad some distance from. . .  [by SK Shenoy, NPOL, Kochi, India]

RS232C Powers & ReaDS 8 Bit Switch Matrix -  04/11/96 EDN Design Idea   The circuit in Figure 1 provides a remote menu-selection switch matrix for PCs. It connects a linear, 8-bit switch to the RS-232C port; the RS-232C signal pins provide the circuit's frugal power requirements. You can easily modify. . .  [by Dhananjay Gadre, IUCAA, Pune, India]

      <<<<Previous   PAGE   Next>>>>