Running Message Display

About
Light emitting diodes are advan- tageous due to their smaller size, low current consumption and catchy colours they emit. Here is a running message display circuit wherein the letters formed by LED arrangement light up progressively. Once all the letters of the message have been lit up, the circuit gets reset. The circuit is built around Johnson decade counter CD4017BC (IC2). One of the IC CD4017BE�s features is its provision of ten fully decoded outputs, making the IC ideal for use in a whole range of sequencing operations. In the circuit only one of the outputs remains high and the other outputs switch to high state successively on the arrival of each clock pulse. The timer NE555 (IC1) is wired as a 1Hz astable multivibrator which clocks the IC2 for sequencing operations. On reset, output pin 3 goes high and drives transistor T7 to �on� state. The output of transistor T7 is connected to letter �W� of the LED word array (all LEDs of letter array are connected in parallel) and thus letter �W� is illuminated. On arrival of first clock pulse, pin 3 goes low and pin 2 goes high. Transistor T6 conducts and letter �E� lights up. The preceding letter �W� also remains lighted because of forward biasing of transistor T7 via diode D21. In a similar fashion, on the arrival of each successive pulse, the other letters of the display are also illuminated and finally the complete word becomes visible. On the following clock pulse, pin 6 goes to logic 1 and resets the circuit, and the sequence repeats itself. The frequency of sequencing operations is controlled with the help of potmeter VR1.
The display can be fixed on a veroboard of suitable size and connected to ground of a common supply (of 6V to 9V) while the anodes of LEDs are to be connected to emitters of transistors T1 through T7 as shown in the circuit. The above circuit is very versatile and can be wired with a large number of LEDs to make an LED fashion jewellery of any design. With two circuits connected in a similar fashion, multiplexing of LEDs can be done to give a moving display effect




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LED Mood Light

LED Mood Light

Introduction

This circuit makes a nice lamp that consumes little power, runs cool, and has an incredibly long lifetime. The lamp puts out a warm yellow shade of light, the color may be adjusted by changing the number of red or green LED strings.

Specifications

Operating Voltage: 12V DC
Operating Current: 80ma approx.

Theory

The current flows and the LEDs light. There are 4 series strings of LEDs in this circuit, the resistors limit the current through the LEDs and prevent them from burning up. The resistors were adjusted to get approximately 20ma through each string. Different LED colors will have different voltage drops and resulting current flows. These resistor values will work fine at 12V.

Construction

The circuit was mounted in a plastic 35MM photographic slide box with a translucent plastic top (not shown). A piece of perforated board was cut to fit inside of the slide box, the LEDs and resistors were inserted through the holes in the board and the wires were soldered together on the back side of the board. It is recommended that you use a heat sink on the LED leads while you solder them, it is very easy to damage an LED with a soldering iron. A length of speaker wire was used to connect the lamp to the power source. The circuit board was connected to the plastic box with one 6-32 screw and several 6-32 nuts were used as spacers.

Alignment

None required

Use

Connect this circuit to a 12V battery or power supply, it puts out a nice glow that won't affect your night vision too much. You can read by this light if you use it at close range.

Parts

10x green LEDs, T1-3/4 size
9x red LEDs, T1-3/4 size
3x yellow LEDs, T1-3/4 size
2x 100 ohm 1/2 W resistors
1x 56 ohm 1/2 W resistor
1x 62 ohm 1/2 W resistor (can also be 56 ohm, it's what I had on hand)
1x 1/2 Amp 28VDC fuse
1x Plastic box with diffused (blurry) top, I used a 35mm slide box.
1x 6-32 3/8" screw
2x 6/32 nuts

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Dancing LEDs

A LED sequencer, following the rhythm of music or speech

9V Battery-operated portable unit

Parts:

R1_____________10K   1/4W Resistor
R2,R3__________47K   1/4W Resistors
R4______________1K   1/4W Resistor
R5,R6,R7______100K   1/4W Resistors
R8____________820R   1/4W Resistor

C1,C3_________100nF   63V Ceramic or Polyester Capacitors
C2_____________10µF   50V Electrolytic Capacitor
C4____________330nF   63V Polyester Capacitor (See Notes)
C5____________100µF   25V Electrolytic Capacitor

D1___________1N4148   75V 150mA Diode
D2-D11_________5 or 3mm. LEDs (any type and color)

IC1___________LM358  Low Power Dual Op-amp
IC2____________4017  Decade counter with 10 decoded outputs IC

M1_____________Miniature electret microphone

SW1____________SPST  miniature Slider Switch

B1_______________9V  PP3 Battery

Clip for PP3 Battery

Additional circuit parts (see Notes):

R9,R10_________10K   1/4W Resistors
R11____________56R   1/4W Resistor

D12,D13 etc.____5 or 3mm. LEDs (any type and color)

Q1,Q2_________BC327   45V 800mA PNP Transistors
Q3____________BC337   45V 800mA NPN Transistor

Device purpose: 

The basic circuit illuminates up to ten LEDs in sequence, following the rhythm of music or speech picked-up by a small microphone. The expanded version can drive up to ten strips, formed by up to five LEDs each, at 9V supply.

Circuit operation:

IC1A amplifies about 100 times the audio signal picked-up by the microphone and drives IC1B acting as peak-voltage detector. Its output peaks are synchronous with the peaks of the input signal and clock IC2, a ring decade counter capable of driving up to ten LEDs in sequence.
An additional circuit allows the driving of up to ten strips, made up by five LEDs each (max.), at 9V supply. It is formed by a 10mA constant current source (Q1 & Q2) common to all LED strips and by a switching transistor (Q3), driving a strip obtained from 2 to 5 series-connected LEDs. Therefore one transistor and its Base resistor are required to drive each strip used.

Notes:

• The sensitivity of the circuit can be varied changing R4 value.
• C4 value can be varied from 220 to 470nF in order to change the circuit speed-response to music peaks.
• Adopting the additional circuit, only one item for R10, R11, Q1 and Q2 is required to drive up to ten LED strips. On the contrary, one item of R9 and Q3 is necessary to drive each strip you decided to use.
• Each R9 input must be connected to IC2 output pins, in place of the LEDs D2-D11 shown. R8 must also be omitted.
• Whishing to use a lower number of LEDs or LED strips, pin #15 of IC2 must be disconnected from ground and connected to the first unused output pin. Example:
  if you decided to use 5 LEDs, pin #15 of IC2 must be connected to pin #1; if you decided to use 8 LEDs, pin #15 of IC2 must be connected to pin #9 etc.
• Current drawing of the circuit is about 10mA.
• Whishing to use a wall-plug transformer-supply instead of a 9V battery, you can supply the circuit at 12V, allowing the use of up to 6 LEDs per strip, or at 15V, allowing the use of up to 7 LEDs per strip.
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Bicycle rear flashing LED light

Parts

Resistors

R1                     3.3k

R2                     33k

R3                     100k

R4                     390ohm

R5                     390ohm

Capacitor

C1                     22uF

C2                     4.7uF

Leds                  5 leds

Transistors

Q1                     BC547

Q2                     BC547

7 Segment LED Counter

This simple counter can be used to count pulses, as the basis for a customer counter (like you see at the doors of some stores), or for anything else that may be counted. The circuit accepts any TTL compatible logic signal, and can be expanded easily

Parts
Resistors          7(470 ohm)
LEDs                7
IC                      U1 (74LS90 TTL BCD Counter IC)
IC                      U2 (74LS47 TTL Seven Segment Display Driver IC)

knight rider leds schematic

Parts
resistors     3.3k,8.2k,10k,100k(6resistor of 1k)
diode          (8 diode   in4001 or 4148)
ic               555 timer and 4017 decade counter
capacitor    10uF,10nF,6.8nF
bettery

Electronic dice

Parst
Resister       R1     22k
Resister       R2    12k
IC               IC1   555 timer
IC               IC2    CD4017
Capacitor    C 1  (0.022uF,50v)
LED                     6leds  
Switch        S       2switches
bettery                 9v

Description:

It is good idea to put this circuit in a box and mark/write each LED with number 1 to 6. Now, when switch S1 is pushed momentarily, any one of the 6 LEDs will glow. The Number marked for glowing LED becomes dice's output. Every time S1 is released, new LED will glow randomly. Chances for each LED to glow is 16.66%.

This circuit makes use of two ICs, IC555 and IC-CD4017. IC-555 is used as square wave generator, and IC(CD4017) as a counter. Actually CD4017 is a divide-by-10 johnson-counter with 10 decoded outputs. IC555 simply generates clock for CD4017, and the clock frequency is controlled by R1 and C1. Counter CD4017 starts counting from 0 to 9 by putting high voltage on each of the 10 pins (one after another). The High voltage shifts from one pin to another on every positive edge of the clock. Since, in our circuit pin-5 is shorted with pin-15(reset), the counter gets reset after reaching 6, and again starts from 0. Now, when S1 is pushed, IC555 generates clock for CD4017. This clock enables CD4017 to count from 0 to 6 by putting high voltage on each of the 6 pins (one after another). These 6 pins are connected to 6 respective LEDs. When S1 is released, high voltage gets latched to any one of the 6 pins, and this becomes output of the DICE