0.3-1.5V LED Flashlight -  It's a little wisp of a circuit that allows you to drive a blue or white LED from a low voltage.  Normally, if you want to light up a blue or white LED you need to provide it with 3, 3.5 V, like from a 3 V lithium coin cell.  But a 1.5 V battery like a AA cell simply will not work.  But using the Joule Thief, it works like a charm.  Not only does it work with a brand new battery, but it works until the battery is nearly dead-- down to 0.3 V.  That's well below the point where your other toys will tell you the battery is dead, so it can steal every last joule of energy from the battery    (hence the name) .  To learn how to make one, watch the video, which is available in a variety of formats.  __ Evil Mad Scientists Laboratories

1 Line Telephone Line Status Indicator -  This circuit monitors one phone line. . . Circuit by Dave Johnson P.E.-June, 2000

1 Microcontroller Pin Drives Two LEDs with Low Quiescent Current -  02/07/08  EDN-Design Ideas Two simple circuits allow a battery-powered microcontroller to drive two LEDs Design by Antonio Muńoz, Laboratorios Avanzados de Investigación del I3A, Zaragoza, Spain, and Arturo Mediano, PhD, GEPM University of Zaragoza, Zaragoza, Spain

1.2MHz White LED Step-Up Converters with Built-In Schottky in ThinSOT -  LT3465 Switching Regulator__ Linear Technology/Analog Devices

1.5 Volt 1970's Style Caboose Marker Flashing Red LED Light -  A circuit that drives a red LED from a 1.5 volt battery and simulates an incandescent light.  Duty cycle can be changed by selecting resistor values __ Designed by Dick Cappels

1.5 Volt Dual LED Flasher -  This 1.5 volt led fasher runs more than a year on a single 'd" cell and alternately flashes 2 LEDs at about a 1 second rate.  The circuit employs a 74HC14 CMOS hex inverter that will operate at very low voltages    (less than 1 volt) .  One section is used as a squarewave oscillator    (pins 1 and 2) , while the others are wired to produce a short 10mS pulse on alternate edges of the square wave so the LEDs will alternate back and forth.  The output sections each use a capacitor charge pump to increase the voltage for the LEDs __ Designed by Bill Bowden

1.5V battery powers white-LED driver -  30-Sep-04 EDN-Design Ideas Although white LEDs are common in a variety of lighting applications, their 3 to 4V forward-voltage drop makes low-voltage applications challenging.  Charge pumps and other ICs are available for driving white LEDs, but they generally don't work with the low supply voltage of 1.5V in single-cell-battery applications Design by Steve Caldwell, Maxim Integrated Products, Chandler, AZ

1.5V LED Flasher -  schematic only, no circuit description at this time __ Designed by Andrew R. Morris

1.5V LED Flasher Oscillator -  The 8-lead plastic mini-DIP LM3909 IC was developed by National Semiconductor in the mid 'seventies of the past century.  It was a monolithic oscillator specifically designed to flash Light Emitting Diodes.  By using the timing capacitor for voltage boost, it delivered pulses of 2 or more volts to the LED while operating on a supply of 1.5V or less.  The circuit was inherently self-starting, and required addition of only a battery and capacitor to function as an LED flasher __ Contact: Flavio Dellepiane, fladello @ tin.it

1.5v LED Flasher Version A -  Many published circuits that flash LEDs need 3 volts or more.  This circuit uses only a single inexpensive C-MOS IC and flashes the LED for a full year on a single 1.5 volt AA alkaline battery cell.  The circuit uses a charge pump technique to provide. . . Circuit by David A. Johnson P.E.-June, 2000

1.5V LED Flashers -  The LED flasher circuits below operate on a single 1.5 volt battery.  The circuit on the upper right uses the popular LM3909 LED flasher IC and requires only a timing capacitor and LED.  The top left circuit, designed by Andre De-Guerin illustrates using a 100uF capacitor to double the battery voltage to obtain 3 volts for the LED.  Two sections of a 74HC04 hex inverter are used as a squarewave oscillator that establishes the flash rate while a third section is used as a buffer that charges the capacitor in series with a 470 __ Designed by Bill Bowden

10 Channel LED Sequencer -  The 4017 is a CMOS decade counter with 10 decoded outputs.  Inputs include a clock    (pin 14) , a reset    (pin 15) , and a clock inhibit    (pin 13)  __ Designed by Bill Bowden

10 LED Chaser -  I don't know why, but people like blinking lights.  You see LED chasers everywhere, in TV shows    (Knight Rider) , movies, and store windows.  This schematic is my version of a simple 10 LED chaser.  There is no 555 timer used because __ Designed by Aaron Cake

10 LED Sequencer -  Schematic only, text in Finnish

10 LED Sequential Flasher using Low Powr -  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. . . Circuit by David A. Johnson P.E.-April, 2011

10 Stage LED Sequencer -  The 4017 is a CMOS decade counter with 10 decoded outputs.  Inputs include a clock    (pin 14) , a reset    (pin 15) , and a clock inhibit    (pin 13)  __ Designed by Bill Bowden

10 Stage Light Sequencer -  schematic only -- flashes 10 low voltage bulbs, operates at10-25-Volt voltage, in PDF format, text in Finnish

10 to 100 LED Sequencer using a Matrix  -  The circuit above illustrates using a 10x10 matrix to sequence up to 100 LEDs with just three ICs and 20 transistors.  The two 4017 decade counters control the 10 rows and 10 columns so that one LED is selected depending on the output of the decade counters.  The LED circuit is drawn showing 25 LEDs and 10 transistors but can be expanded up to a 100 __ Designed by Bill Bowden

100ma UltraLow Noise Charge Pump LED Supply with Output Current Adjust -  LTC3201__ Linear Technology/Analog Devices

11 to 100 LED Sequencer using a Matrix  -  The circuit above illustrates using a 10x10 matrix to sequence up to 100 LEDs with just three ICs and 20 transistors.  The two 4017 decade counters control the 10 rows and 10 columns so that one LED is selected depending on the output of the decade counters.  The LED circuit is drawn showing 25 LEDs and 10 transistors but can be expanded up to a 100 __ Designed by Bill Bowden

12 Stage Neon Sequencer NE 2/NE 51 -  This circuit is similar to the LED clock using 12 neon indicator lamps instead of LEDs.  It operates from 2 high capacity ni-cad cells    (2.5 volts) which keep it going for a couple weeks.  High voltage    (70 volts) for the neon lamps is obtained from a small switching power supply using a 74HC14 Schmitt trigger squarewave oscillator, high voltage switching transistor __ Designed by Bill Bowden

12 Volt Knight Rider LED display -  12 Volt Knight Rider, "Look-A-Like", Lighting Systems Revised "JAN.2, 2008"  (Errors on Knight-3, Corrected)  __ Designed by G.L. Chemelec

120 & 240VAC LED Voltage Indicator -  Useful for power lines control.  Simple, transformerless circuitry __ Contact: Flavio Dellepiane, fladello @ tin.it

120 VAC / 240 VAC Indicator -  Two LEDs indicate if a power line has 120vac or 240vac voltage on it . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2006

120VAC Lamp Chaser using Solid State Relays -  This circuit is basically the same as the 10 channel LED sequencer with the addition of solid state relays to control the AC lamps.  The relay shown in the diagram is a Radio Shack 3 amp unit    (part no.275-310) that requires 1.2 volts DC to activate.  No current spec was given but I assume it needs just a few __ Designed by Bill Bowden

12V White LED Driver -  DC powered LED lighting circuits can vary from trivial single LEDs with series resistors and LEDs with simple analog current regulators to more complicated switching power supply circuits such as this project. There is a tradeoff between simplicity and circuit capabilities. This more complex circuit adds features such as regulated light level across a wide range of input voltages and automatic circuit shutoff on low input voltage. __ Designed by G. Forrest Cook

13 Color LED Rainbow -  Only a few years ago, the choice of LEDs was limited to IR, red, yellow, and green.  The LED manufacturers have been busy extending the spectrum, and filling in the gaps.  The latest generation of organic LEDs    (OLEDs) has added some dazzling new colors to the spectrum.  This circuit uses a set of 13 differently colored LEDs to generate a full color spectrum.  The photo does not fully represent the colors generated due to camera limitations __ Designed by G. Forrest Cook

13 Volt Lamp Dimmer (using a pot) -  Here is a 12 volt / 2 amp lamp dimmer that can be used to dim a standard 25 watt automobile brake or backup bulb by controlling the duty cycle of a astable 555 timer oscillator.  When the wiper of the potentiometer is at the uppermost position, the capacitor will charge quickly through both 1K resistor __ Designed by Bill Bowden

15–58VIN to 33.3V 3A LED Automotive Headlight Driver with Up to 98.5% Efficiency -  Airplanes and big trucks with 24V batteries need powerful, efficient and robust headlights and spotlights.  This circuit shows a 33.3 V, 3A    (nine Luminus SSR-90 LEDs) buck-boost LED driver that runs from 15V to 58V input with up to 98.5% efficiency.  The 4-switch synchronous topology drives high power LEDs with minimal switch power loss    (and minimal temperature rise) __ Linear Technology/Analog Devices App Note, Mar 9th 2012