LED Sequencer Circuit

Descrete Multistage Light Sequencer Circuit
The drawing below illustrates a multistage light sequencer using
descrete parts and no integrated circuits. The idea is not new
and I hear a similar circuit was developed about 40 years ago
using germanium transistors. The idea is to connect the lights so
that as one turns off it causes the next to turn on, and so forth.
This is accomplished with a large capacitor between each stage
that charges when a stage turns off and supplies base current to
the next transistor, thus turning it on. Any number of stages can
be used and the drawing below illustrates 3 small Christmas lights
running at about 5 volts and 200mA. The circuit may need to be
manually started when power is applied. To start it, connect a
momentary short across any one of the capacitors and then
remove the short. You could use a manual push button to do this.

16 Stage LED Sequencer Circuit
The circuit below uses a hex Schmitt Trigger inverter (74HC14)

and two 8 bit Serial-In/Parallel-Out shift registers (74HCT164 or

74HC164) to sequence 16 LEDs. The circuit can be expanded to

greater lengths by cascading additional shift registers and

connecting the 8th output (pin 13) to the data input (pin 1) of the

succeeding stage. A Schmitt trigger oscillator (74HC14 pin 1 and 2)

produces the clock signal for the shift registers, the rate being

approximately 1/RC. Two additional Schmitt Trigger stages are

used to reset and load the registers when power is turned on.

60 Light Sequencer Circuit using a Matrix

The circuit below 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 by using sucessive stages of the

4017 counters.

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LED sequencer
The model 4017 integrated circuit is a CMOS counter with ten

output terminals. One of these ten terminals will be in a "high"

state at any given time, with all others being "low," giving a

"one-of-ten" output sequence. If low-to-high voltage pulses are

applied to the "clock" (Clk) terminal of the 4017, it will increment

its count, forcing the next output into a "high" state. With a 555

timer connected as an astable multivibrator (oscillator) of low

frequency, the 4017 will cycle through its ten-count sequence,

lighting up each LED, one at a time, and "recycling" back to the

first LED. The result is a visually pleasing sequence of flashing

lights. Feel free to experiment with resistor and capacitor values

on the 555 timer to create different flash rates

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led flashing circuit

Transistor LED flasher Circuit

This circuit has a lot going for it. For one thing, it only consists of two
transistors, two capacitors and four resistors. That also means it
consumes very little power. You can control the flash rate by changing
the size of the 100k resistors (100k makes for a pretty slow rate).
You can also control the duty cycle by using resistors of different
values on the two sides. The 470 ohm resistors control the current
through the LEDs. Normally you want to limit this to 20mA, but to
conserve battery power, you may need to limit it even further. You
can also connect several LEDs in series, instead of using only one
for each side. With red LEDs (1 per side) and the values shown,
the circuit draws about 11mA.
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Basic LED flasher circuit using NE555 timer IC
This circuit consumes more power, but it's advantage is when

you need a variable flash rate, like for strobe circuits. You can

actually use this circuit as a remote control for strobes that have

a remote input. Of course, it has many other applications

besides strobes.

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4 Parallel LEDs flashing circuit
Nominal flash rate: 1.3 Hz. Average IDRAIN e 2 mA

LM3909 LED Flasher/Oscillator
General Description
The LM3909 is a monolithic oscillator specifically designed
to flash Light Emitting Diodes. By using the timing capacitor
for voltage boost, it delivers pulses of 2 or more volts to the
LED while operating on a supply of 1.5V or less. The circuit
is inherently self-starting, and requires addition of only a battery
and capacitor to function as an LED flasher.
Packaged in an 8-lead plastic mini-DIP, the LM3909 will operate
over the extended consumer temperature range of
b25§C to a70§C. It has been optimized for low power drain
and operation from weak batteries so that continuous operation
life exceeds that expected from battery rating.
Application is made simple by inclusion of internal timing
resistors and an internal LED current limit resistor. As
shown in the first two application circuits, the timing resistors
supplied are optimized for nominal flashing rates and
minimum power drain at 1.5V and 3V.

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12 LED Flasher
LED flasher in this circuit use 12 LED it can show 2 style .

The circuit consist 2 section

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1.5 volt dual LED flasher Circuit
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.

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