Offline Supply Drives LEDs  -  04/21/11  EDN Design Idea   Keep LEDs lit when AC voltage drops. LEDs need power when rectified ac-mains voltage drops during its cycle. The circuit in Figure 1 lets you use an inductor-less, switching, offline power supply as an LED driver for emergency-exit signs and neon-light replacements. The design uses off-the-shelf components, offers efficient operation without an inductor in the dc side of the circuit, has no high-voltage capacitors, operates directly from either 120 or 230V ac, has minimal power dissipation, and has adjustable output voltage. . .  [by TA Babu, Chennai, India]

On/Off Latch Circuit with 2 Second Delay  -  A Discover Circuits visitor needed a latch circuit which could operate using a power supply voltage ranging from 3v to 24v. He wanted to use a tiny pushbutton switch to turn on and off power to a load. However, he wanted a 2 second delay between the switch activation and the state change of the output . . . [Circuit by David Johnson P.E.,  06/30/13]

On/off Pushbutton Switch with 30 Minute Timeout  -  I received an email from a Discover Circuits visitor. He wanted to control power to a LED camping light he was building. He wanted to turn the light on and off with a small pushbutton switch. He also wanted a timer so the light would not stay on longer than 30 minutes at a time. It seems that his kids often turned lights on when going to bed and then forgot to turn them off . . . [Circuit by David A. Johnson P.E.,  01/08/12]

On/Off Switch With Latching Relay  -  The circuit below switches AC or DC power to a load using an ultra low power 3v latching relay with two coils. The relay can handle about 10 Amps of current, up to 250vac. Each time the small pushbutton is pressed, the circuit either latches the relay . . . [Circuit by David A. Johnson P.E.,  12/24/09]

One component drives stepper motor  -  The extremely simple circuit in Fig 1 drives a stepper motor directly from 12V ac , 60 Hz power supply. Usually you need switched-dc voltages to drive a stepper motor. But a stepper motor will run off ac lines if you introduce a 90° phase shift between the voltages applied to the motor's two windings. In this case only one 6. 8uF non polarity capacitor is needed. . .   

One I/O line drives shift register with strobe  -  03/28/13  EDN Design Idea   This Design Idea shows how a single microcontroller port can drive a lot of output lines through shift register. . .  [by Zoran Mijanovic & Nedjeljko Lekic]

One Microcontroller Pin Drives Two LEDs With Low Quiescent Current  -  02/07/08  EDN Design Idea   Two simple circuits allow a battery-powered microcontroller to drive two LEDs. . .  [by Antonio Muñoz, Laboratorios Avanzados de Investigación del I3A, Zaragoza, Spain, and Arturo Mediano, PhD, GEPM University of Zaragoza, Zaragoza, Spain]

One microcontroller pin senses ambient light, controls illumination  -  10/26/06  EDN Design Idea   LED circuit senses light and controls its own brightness. . .  [by Loren Passmore, Berkeley, CA]

One Nimh Cell powers White LED  -  There are a lot of white LED driver circuits floating around. A popular circuit called the “Joule Thief” can drive one white LED from a single 1. 2v or 1. 5v battery cell. Most of these circuits use one or two transistors to form a voltage boost circuit . . . [Hobby Circuit designed by David A. Johnson P.E.,  09/26/09]

One wire brings power & data to LCD module  -  01/27/14     EDN Design Idea   If you need to connect a small remote LCD display, or your µC has run out of I/O pins, here’s a good, cheap solution - Embedded systems frequently use HD44780 - type LCD displays as it is considered the most popular alphanumeric display controller. The interface comprises at least 14 pins: eight for data, three for control (EN, WR, RS), two for power supply (VDD, VSS), and one for contrast (Vre). Configured in 8 - bit mode, it requires at least 10 I/O lines (D0D7, EN, RS). Configured in 4 - bit mode, it requires at least six I/O lines (D4D7, EN, RS). . .  [by Benabadji Noureddine]

One-Line Telephone Line Status Indicator  -  This circuit monitors one phone line . . . [Circuit by David Johnson P.E.,  06/10/00]

One-Watt White LED Night Light  -  This simple circuit is designed to plug into a standard AC electrical outlet. It uses four super bright white light emitting diodes (LED) in conjunction with a capacitor coupled full wave rectifier circuit. The LEDs are mounted in a box and are angled slightly . . . [Hobby Circuit designed by Dave Johnson P.E.,  11/06/08]

Op Amps in Line-Driver and Receiver Circuits — Part 1  -  Analog Devices-Analog Dialogue. . .  [by Jung, Walt]

Op Amps in Line-Driver and Receiver Circuits — Part 2  -  Analog Devices-Analog Dialogue. . .  [by Garcia, Adolfo and Jung, Walt]

Optical Channel Identification on the ADN284x Laser Drivers  -  AN-658 Analog Devices App Note - . . .   

Optical feedback extends white LEDs' operating life  -  01/18/07    EDN Design Idea   PWM-controller loop stabilizes light output. . .  [by Bjoy Santos, Intersil Corp, Milpitas, CA]

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