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18 Stage LED Sequencer - The question sometimes comes up of how to cascade 4017 decade counters for more than 10 sequencial stages. The LED sequencer above shows a possible solution using a few extra parts. When power is applied, the 15K resistor and 10uF cap at pin 15 will reset the counters to the zero count where pin 3 is at +12 and all other outputs are at zero. The 2 diodes (1n914) and 15 resistor form a AND gate so the clock pulse will be passed to the right side counter when the sequence starts. When the right counter reaches the 10th count, . __ Designed by Bill Bowden 1a Low Noise High Current LED Charge Pump with Independent Torch/Flash Current Control - LT3216__ Linear Technology/Analog Devices
1-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 Johnson P.E.-September, 2009
1us LED Pulse Driver + Voltage to Frequency Converter - This circuit receives the signal from the above amplifier and launches powerful 1uS infrared light pulses from a low cost LED that are frequency modulated by the audio information. The 10KHz center frequency of the pulse stream is low enough so a standard . . . Hobby Circuit designed by Dave Johnson P.E.-March, 1999
1W White LED Night Light - As many of you know, I have a pet peeve with poorly made LED night lights. Often, the light from the LED quickly fades, so within months, the light is useless. I have posted several versions of modified night lights using higher quality components. This circuit is yet another version, which produces much more light than those other designs. . . . Hobby Circuit designed by David A. Johnson P.E.-November, 2008
2 LED trouble light systE - M - No circuit description, schematic only__ CdS Electronic
2 LEDs Perform Rudimentary Spectral Analysis - 09/01/94 EDN-Design Ideas A pair of LEDs having different wavelengths can supply the stimulus for a rudimentary spectral analysis during quality-control sorting operations. By measuring the reflectance of each LED, the circuit in Fig 1 can provide information about the spectral response of the object under test. The circuit's Design by Peter Bojilov, Isomatik Sortex Ltd, Pazardjik, Bulgaria
2 PIC pins drive six LEDs - 06/09/14 EDN-Design Ideas Here’s a take on LED multiplexing with minimal output pins. This Design Idea demonstrates a new method of driving six LEDs with only two I/O lines from a microcontroller, and so is particularly suitable for any pin-limited chip. It uses a pair of I/O lines combined with a pair of complementary bipolar transistors. Design by Benabadji Noureddine
2 Signals Easily Control Tricolor LED - 09/14/95 EDN-Design Ideas Tricolor LEDs come in two- and three-pin packages. Although the three-pin, or common-cathode, package easily lends itself to 2-bit control, wiring three crowded pins can be mechanically difficult. Also, fewer manufacturers produce the three-pin types. The two-pin package is easier to connect to a wiring harness and is readily available. However, this package requires more control overhead, because, to light the LED yellow, the device must continuously alternate between red and green. Design by Bob Richards, Digital Audio Corp, Raleigh, NC
2 Transistor Flasher - The basic two-transistor flasher shown below has found its way into dozens of applications due to its simplicity and versatility. Applications have included such diverse circuits as a micropower low battery indicator, a lightning detector, a off-line. __ Contact: Charles Wenzel of Wenzel Associates, Inc.
2 Transistor 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
2 Transistor LED Flasher - This circuit will flash a bright red LED as an attention getting device or fake care alarm. __ Designed by Bill Bowden
2 Transistor LED Flasher - This is a classic 2 transistor astable multivibrator. Many other NPN small signal or switching transistors can be used, including 2N4401, PN2222 or 2N2222 using the circuit on the left. The circuit can also be inverted using PNP transistors. __ Designed by Bill's Electronics Reference Library
2 Transistor LED Flasher - Classic astable multivibrator using 2 transistors. Transistor is not critical. Try these: 2N4401, 2N2222, NTE123A, NTE123AP, NTE159, TUP/TUN and those in your junk box, you may find that most of them will work. __ Designed by Tony van Roon VA3AVR
2 Transistor LED Flasher 1 - Circuit Only __ Designed by Tony van Roon VA3AVR
2 Transistor LED Flasher 2 - This circuit will flash a super-bright LED (5000+ mcd) . Good for fake car alarm or other attention getting device. Component values are not critical, try anything else first from your junkbox. Obviously, the 470 ohm resistor (R3) determines the LED's brightness and limits the current flow to about 20mA.390 ohm can also be used as a save value. If you decide to go with a green or yellow led, which draw more current, you may want to replace the 470 ohm with an appropriate value. Flash rate is determined by R2 and C1 __ Designed by Tony van Roon VA3AVR
2 transistor lights LEDs - 04/09/09 EDN-Design Ideas A previous Design Ideasdescribes a circuit that uses an astable multivibrator to drive an LED (Reference 1]. The circuit in Figure 1 uses a simpler alternative approach. The circuit uses a 2N3904 NPN transistor and a 2N3906 PNP trans Design by Barry A Tigner, Michigan State University, East Lansing, MI
20mA LED Ballast - (corrected text) I use this circuit for general use to power white LEDs, like a headset light I use on my desk and a keyboard light for my computer. I built it into a tiny Radio Shack project box (270-288) , which y no longer sell. I put heat-shrink tubing __ Designed by Andrew R. Morris
20 LED Night Light - After 3 years of continuous 24/7 operation I noticed that the 20 LED array I was using as a night light next to my back door was fading. Some of the LEDs were much dimmer than others. I figured that over time, the internal heat dissipated from the LED chip was causing the LED light intensity to fade. I decided it was time to replace the light. . . . Circuit by David Johnson P.E.-July, 2017
220v AC Powered Blinking Led - I needed a pulsating light for a certain signaling. Voltage was 230V. So I decided to make a simple circuit, consisted of a LED diode, two capacitors, two resistors, a diac and a diode. Activity of the circuit is extraordinarily simple. The capacitor charges by the diode and the resistor. When the voltage on the
220V Blinking LED - This is a simple blinking led circuit powered from 220V that can be used to mark special places or as voltage indicator. The voltage from the mains charges the capacitor through R1 resistor and D1 diode.
230V Rotating & Blinking LED - This design can be of some interest for those wanting striking light signs, as it can drive up to three 230V lamp strings in three operating modes. The 15V dc supply is obtained from a nominal 230/24V center tapped ac transformer (T1) and a full wave rectifier __ Contact: Flavio Dellepiane, fladello @ tin.it
24 Volts AC to 24 Volts DC Power Supply - The idea for the circuit below came from a company needing to power several 24v DC LED assemblies from an existing 24vac supply. They did not need a rock solid and regulated 24 volts but a voltage which hovered around that voltage. Running the AC through . . . Hobby Circuit designed by David Johnson P.E.-February, 2011
24V DC Powered Beeper with 4 Separate Inputs - 24vac is a popular voltage. It is often used in low voltage lighting systems and industrial controls. It is much less dangerous than 120vac/240vac line voltages. This hobby circuit below is one method to efficiently power a cluster of 7 white LEDs from 24vac. . . . Hobby Circuit designed by David A. Johnson P.E.-December, 2009
25 LED Chaser (Sequencer) - A Fairly Simple C-Mos Circuit. __ Designed by G.L. Chemelec
25 Light Sequencer using Xmas Lamps - This circuit above can drive 25 small Xmas lights. The lights operate at about 200mA and 3 volts. The supply voltage is set to 5 volts and the 4017 counter output will drop about a volt using the 2N3053 transistors. The voltage on the emitters of the rows transistors will be about 0.7 volts less than the base so the lamp voltage will be about 3 volts. You can __ Designed by Bill Bowden
28 LED Clock - This is a programmable clock timer circuit that uses individual LEDs to indicate hours and minutes.12 LEDs can be arranged in a circle to represent the 12 hours of a clock face and an additional 12 LEDs can be arranged in an outer circle to indicate 5 minute intervals within the hour.4 additional LEDs are used to indicate 1 to 4 minutes of time within each 5 minute interval. __ Designed by Bill Bowden |
