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Building an LED circuit?

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lfansler

New Member
Does anyone know if its possible to build a flashing LED circuit with 8 lights flashing in a random pattern and the interval between flashes controllable? If possible I would like the lights to stay lighted for about 2 seconds then go off, and the interval between the next light to be about 5 seconds or controllable. I have no idea what hardware I would need for such a project, any help would be appreciated! Thanks
 
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lfansler

New Member
Re: microController

I would like it to be as simple as possible, what do you mean "time to learn the program?"
I thought I was posting my questions to the forum.
 

crutschow

Well-Known Member
Most Helpful Member
A brute force approach is to use eight 555 timers, each one controlling an LED. They would fire at random intervals with respect to other and you can adjust the flash interval of each one independently.
 

RODALCO

Well-Known Member
Cd 40106

A 40106 IC can drive 6 led's at random.

Each driver requires a capacitor and a resistor of different value to make them switch a led on or off.

You need to use two of those IC's.
 

birdman0_o

Active Member
Found your answer in one chip
CD4060
Has 8 timer dividers and adjustable RC timer (you just need to use a pot)
Heres a page on how it works
Electronics timer by CD4060

Arrange the leds in a certain order and if you want two on the same frequency you can use a pnp and an npn transistor as switches, one will be on when the signal is low and the other will be on when it is high...



Good luck,
Mike
 

Sceadwian

Banned
If you don't know what you're doing you should be looking for a kit online that includes all the parts and the schematic.
 

lfansler

New Member
If I was looking for a kit on-line how would I be specific about the parts and schematics? Any site you recommend?
 

Sceadwian

Banned
This thread now has 3 clones in the forums...
 

blueroomelectronics

Well-Known Member
As I posted in the other thread, a microcontroller could do this with more apparent randomness* than a simple logic gate device. An 18F1320, 8 LEDs, 8 resistors (330 ohm) plus power supply & decoupling would be the minimum. I suggest the 18F as it's dead easy to write a program in Swordfish BASIC SE that would use the random module available for that compiler.

*Not easy to get true random numbers in a digital world...

PS an example of what you mean by delays, random etc would help. Like stars flickering?
 
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jimlovell777

New Member
I've not tested this but if you want "random" try a 555 timer feeding an 8-bit serial-in parallel-out shift register. That will handle the 8 LEDs desired. To make it *cough* random just leave the Data pin floating. The CLK will/can be adjustable as you stated you wanted, the timing would remain constant but the LEDs will light in an indiscriminate manner.

As mentioned previously a kit or a microcontroller would be the best way to go. If for no other reason than reduced complexity.

As with most electronics projects tasks can be handled in a sometimes staggering number of ways. Find the way that best suits your project. You should have a hint of what you want out of any design and head down that road.
 

lfansler

New Member
re

As I posted in the other thread, a microcontroller could do this with more apparent randomness* than a simple logic gate device. An 18F1320, 8 LEDs, 8 resistors (330 ohm) plus power supply & decoupling would be the minimum. I suggest the 18F as it's dead easy to write a program in Swordfish BASIC SE that would use the random module available for that compiler.

*Not easy to get true random numbers in a digital world...

PS an example of what you mean by delays, random etc would help. Like stars flickering?
I would like the lights to remain lighted for approx 1-2 seconds and a delay between lights to be about 5 seconds, if not controllable. thanks again for any ideas
 

jimlovell777

New Member
Does the "random" pattern need to change each cycle or do the LEDs need to appear to light at random? If it's the latter I might have an idea for you.
 

jimlovell777

New Member
Here's something I came up with that may work for you.



The top two sections of the 4001 IC form an adjustable "one shot" timer and should be adjusted to provide the 2 sec LED on time you requested. The bottom two sections of the 4001 IC form a square wave oscillator that provides the 5 second CLK delay to trigger the next LED in the sequence. Each time the next LED is lit the one shot is fired again to light the LED for 2 seconds and then turn off. The pattern is not random but if the LEDs are placed randomly the desired effect could/might be achieved.

Edit: I just realised I forgot to add a current limiting resister, simply add one between the LEDs and the transistor. Only one LED is ever lit so only one resistor is needed.
 
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