|
Light/Dark 12V Switch - Often, for certain low voltage lighting systems; you would like to turn off the lights during the bright light of the day. Most commercial day/night switches are designed for AC lighting. The circuit below was designed for a 12v DC system. But, it could be modified for other voltage as well. It uses an inexpensive phototransistor as the light detector.. . . Circuit by David Johnson P.E.-June, 2008
Light/Dark Detector drives a relay - This handy little circuit can tell the difference between darkness and light, making it very useful for switching on and off signs, porch lights or other things when it gets dark or light. __ Designed by Aaron Cake
Light-controlled oscillator uses solar cell junction capacitance - 08/08/13 EDN-Design Ideas Learn how solar cell characteristics can be harnessed for a light-sensitive oscillator. Any PN junction diode can be used as a variable capacitor in reverse biased mode, as well as in the forward biased mode before the knee voltage. The capacitance is usually very small as the junction size is small. Though the varactor diode is specially designed for higher capacitance, it's still limited to a few hundred picofarads. A solar cell can also be used in some circuits as a variable capacitor. As its junction size is much larger than the usual diodes, much larger variation of capacitance is expected. Design by sajjad Haidar
Lighthouse LED Flasher - This was originally designed for a model in a HO train set. It simulates the behavior of the light from a lighthouse. The LED intensity gradually increases, then flashes with a bright light and finally decreases slowly in intensity. . . Circuit by David Johnson P.E.-July, 2006
Lighting SystE - M - how to inexpensive, portable lighting system that add a great deal of ambiance to the music performance, includes simple controller circuit
LightningCreate an electrical storm in a light bulb - The Lightning Bulb circuit uses a quadrac (see Fig.1) --a device that combines a TRIAC and a diac trigger in a single package--to control the supplied current. Figure 1A shows the schematic symbol for the quadrac, while figure 1B shows the pinout for the unit used in our circuit. Note that quadracs are increasingly difficult to come by;. __ Designed by Vincent Vollono
Lights Control for Model Cars - NOTE
: Must register on this site __ Designed by Published in Elecktor July/Aug, 2010
Lights timer - Automatically turn off the lights after 10 minutes. If you often forget to turn off the lights outside or at different places in the house, this circuit can be practical for you. It can control two independent light switches with different turn off times. Press the button once and the light turns on for the preset time. Press again, and the light remains on forever. Press for the third time, and the light turns off __ Designed by Peter Jakab
Line Powered Flashers - Scroll to find this one. Here is an unusual flasher circuit for 120VAC loads. The circuit is similar to the two-transistor flasher seen in several circuits in techlib. com except that an SCR is used __ Contact: Charles Wenzel of Wenzel Associates, Inc.
Line Powered High Intensity LED Flasher - There are times when you would like to generate an intensely bright flash of light using electrical power from the AC line. The circuit below can drive a one to three watt power LED with about 350ma of peak current. Since the circuit drives the LED with . . . Hobby Circuit designed by David Johnson P.E.-December, 2008
Line Powered White LED Array - There has been a lot of excitement lately in the lighting industry. Some companies are beginning to manufacture general lighting fixtures, which replace incandescent and fluorescent lamps, using LED lights. When proper heat management is designed. . . Circuit by David A. Johnson P.E.-February, 2010
Line Powered White LEDs - The LED circuit above is an example of using 25 white LEDs in series connected to the 120VAC line. It can be modified for more or less LEDs by changing the R value. The exact resistance value will depend on the particular LEDs used. In operation, a DC voltage of around 170 is produced from the bridge rectifier and 50uF capacitor. The capacitor value is not critical __ Designed by Bill Bowden
Linear & Switcher LED Supplies Combine, Overcome Disadvantages of Each Topology - 01/08/2013 To control their brightness, LEDs need a constant current; this can be done with a resistor placed in series with the LED string. Both the LED-string voltage and the supply voltage can vary, so a dedicated LED driver is a must to guarantee the current accuracy. Two solutions—each with advantages and disadvantages—are widely used: a linear constant-current LED driver or a step-down switching converter. Design by Fabien Franc, On Semiconductor, Phoenix
Linear Constant Current LED Lamp Dimmer - This circuits drives 24 white light LEDs with an adjustable constant current
Linear-brightness controller for LEDs has 64 taps - 03/15/07 EDN-Design Ideas Digital potentiometer controls the brightness of LEDs Design by Ahmad Ayar, Maxim Integrated Products, Sunnyvale, CA
Line-Powered Xenon Flash Transmitter - This line powered xenon flash circuit drives a small camera type flash tube. It has an optical isolator to allow the flash to be safely triggered from some remote device. A flash rate of 2Hz is possible with the circuit. . . Circuit by David A. Johnson P.E.-June, 2000
Little bike light using LEDs - No circuit description, schematic only__ CdS Electronic
LM3909 LED flasher - LED flasher with the LM3909 IC and runs from1.5-Volt battery. __ Designed by Tony van Roon VA3AVR
Loudspeaker Protection & Muting - Many hi-fi amplifiers and professional power amps (and loudspeaker systems) provide some of protection, either to protect the speakers from an amp fault, and/or vice versa. Some of these are implemented at a very basic level, for example the use of a 'poly-switch'. The poly-switch is a non-linear resistor, having
Low Battery Indicator - File contains several designs, please scroll to find this circuit. Here is a low battery indicator that flashes a lamp when the battery voltage falls below about 5 volts. The circuit draws about 25 microamps when not flashing so battery life is not significantly shortened by the circuit. The two 1 megohm resistors set the switching point at V/2 (plus a little due to the emitter-base diode drop) and when this voltage is above the zener voltage the circuit cannot turn on. When the battery voltage drops below 5 volts, the base voltage drops to 2.5 volts and the emitter can reach a voltage sufficient to turn on the PNP (2N4403 or similar) . When the PNP conducts, the NPN also conducts dropping the voltage across the circuit even more and the circuit snaps on. When the 4.7 uF capacitor has discharged, the circuit turns off and the capacitor begins charging again. __ Contact: Charles Wenzel of Wenzel Associates, Inc.
Low Battery Indicator Ii - This circuit indicates the remaining battery life bAy varying the duty cycle and flash rate of an LED as the battery voltage decreases. In fact, the circuit actually indicates five battery conditions: (1) a steady glow assures indicates that the battery is healthy; (2) a 2Hz flicker (briefly off) indicates that the battery is starting
Low Battery Voltage Flasher - This circuit is designed to monitor two alkaline cells (3v) that form the battery often used in portable electronic equipment. . . Circuit by David A. Johnson P.E.-January, 1998
Low cost/ Automatic Emergency Light - The circuit comprises two sections: charger power supply and LED driver.The charger power supply section is
built around 3-terminal adjustable regulator (IC1) LM317, while the LED driver section is built around transistor BD140 (T2) . In the charger power supply section, input AC mains is stepped down by transformer to deliver 9V, 500mA to the bridge rectifier, which comprises diodes (IN4007x4) . __ Contact: IQ Technologies
Low Current Flashing LED Power Indicator - This circuit flashes a power indicator LED to keep the average current low . . . Hobby Circuit designed by David Johnson P.E.-June, 2000
Low Power Blink LED - Schematic only, no circuit description __ Designed by Rob Crockett
Low Power LED Flasher - Judging from the numerous references I have received, this electronic circuit, hobby circuit seems to be rather popular. Many published circuits which flash LEDs need 3 or more volts. This electronic circuit uses only a single inexpensive C-MOS IC and . . . Hobby Circuit designed by David A. Johnson P.E.-June, 2000
Low Power LED Flasher - It doesn't get much simpler than this circuit. Four components counting the battery! How can an LED be illuminated by a 1.5V circuit, when the forward voltage of an LED is about 2V? The LM3909 uses the 100uF capacitor as a charge reservoir, building up a voltage of about 2V before discharging the cap through the LED.
Low Power Sequential Flasher using 10 LEDs - A while back I posted a flasher circuit which flashed 10 LEDs sequentially. That circuit was powered by four AA alkaline cells. The circuit below operates much the same way but has been modified to run from a single 3v CR2032 lithium coin cell . . . Hobby Circuit designed by David A. Johnson P.E.-April, 2011
Low Power Universal LED Flasher - This low power LED flasher circuit draws about 100ua from any DC power supply ranging from 3 volts to 24 volts. The 1.0Hz 10ms LED pulsed current is held to a constant 10ma. . . Circuit by David Johnson P.E.-July, 2006
Low Voltage Light Dimmer - A light dimmer is a means of controlling the "brightness" level of a lamp, in this application we will use a555 Timer to control the brightness level of a low voltage incandescent bulb of up to 60-Watts. For the light dimmer to work the555 Timer is configured as a "variable cycle", astable oscillator running some where around300 Hz
Low-Cost Converter Drives Fluorescent Tube - 03/31/94 EDN-Design Ideas In the last few months, several designers have published circuits for cold-cathode fluorescent-tube (CCFT) power supplies, and a specialized power-supply IC is also now available. However, a significant number of CCFT applications Design by Steven C Hageman, Calex Manufacturing Co, Concord, CA
Low-Cost Dusk-Dawn Controller - This dusk-dawn controller is built around a light-dependent resistor among other components. The common battery supply is used for operating the circuit as well as for load, that is, for power LED/small inverter circuit. Resistors work as voltage divider and current limiter in the circuit. LEDs are used as circuit deactivation indicator. An n-channel MOSFET is used for the switching action of an LED light.__ Electronics Projects for You
Low-loss powers solar lantern - 1-Apr-04 EDN-Design Ideas The solar-lantern circuit in Figure 1 is a low-loss configuration that uses a 7W, four-pin CFL (compact fluorescent lamp] and a 12V, 7-Ahr, sealed, maintenance-free battery. The inverter features greater-than-85% efficiency, less-than-2-mA quiescent current, and a shunt-charge controller with deep-discharge and overcharge protection for the battery Design by Ramsesh Kumar, Bangalore, India
Low-voltage light dimmer - A light dimmer is a means of controlling the "brightness" level of a lamp, in this application we will use a555 Timer to control the brightness level of a low voltage incandescent bulb of up to 60-Watts. For the light dimmer to work the555 Timer is configured as a "variable cycle", astable oscillator running some where around300 Hz
LT3518 Full-Featured 45V, 2.3A Switch Current LED Driver-Video Product Brief - The LT3518 is a current mode DC/DC converter with an internal 2.3A, 45V switch specifically designed to drive LEDs. The LT3518 operates as a LED driver in boost, buck and buck-boost modes. It combines a traditional voltage loop and a unique current loop to operate as a constant-current source or constant-voltage source. Programmable __ Linear Technology/Analog Devices App Note, Steve Knoth-Senior Product Marketing Engineer Aug 25th 2010
Lx 800 Lighting SystE - M - Light is always needed for theatre and live music, and this is just the ticket __ Designed by Rod Elliott ESP |
