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Flashing LED project. help!

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lfansler

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Does anyone have any suggestions for creating a ciruit of 8 LEDs which will light on a random pattern and have the interval between lights controllable? I was told a microcontroller could aid in this. Is this possible to do as a home-project? I'm not very adept at electronics...any guidance or suggestions would be great! Thanks!
 

lfansler

New Member
RE:

I'm sorry, I think I had this open before you sent me a possibility. Thank you for your advice though. What would power the LEDs, the IC, and the transistors? Do you think there are kits and schematics for this type of project already available somewhere?
 
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birdman0_o

Active Member
Well, that is in the case of you wanting two leds to have the same frequency, but the IC can directly power the leds (DON'T forget a current limiting resistor of course!)

The chip is relatively cheap and operates up to 20V, ive made christmas lights out of it before, had 3 different on and off patterns.

Mike
 

R2-D2

Member
I like circuits like these that do things randomly.

The best and simplest way to produce a truly random output (that I know of) is through the use of relaxation oscillators. It uses discharging capacitors that discharge when gas in neon bulbs ionize - which is random.

Neon bulbs that flicker (due to lower pressure of neon gas inside them through their long use) probably would be ideal. You can see this effect on those little battery operated neon flickering candles you can get at hobby stores. You can also sometimes see this flickering effect inside the orange glowing rocker switches on AC power strips from the neon bulbs inside them - after several years of use.

Take a look at the Nothing Box by Mike Ellis:
Nothing Box

For this application, neon bulbs would be better to use but if you still want to go with using LEDs, you would have to connect them across each group of resistor, capacitor and neon bulb group as illustrated in the above circuit and just cover the neon bulbs to cover their lighting. You just have to be sure to limit the voltage and current discharges through each LED so that you don't burn them out. Use a current limiting resistor for each LED. I would start with an experimenter board first and hook up one LED, neon bulb, capacitor and resistor with a 12V source first. I'm not exactly sure on the configuration of hooking up an LED with the relaxation oscillators, but I would experiment first.

Here's another circuit, but not truly random outputs, it just appears that way since it's driven by the 555 timer:
8 Random Flashing Leds Circuit


Google these for more complex ways:

random number generator ic (like how a scientific calculator generates random numbers for statistics.)

Random Number Generator by IC 4017 and 4011 | Circuit Project Electronic

random numbers via quantum mechanical randomness [diode noise]

Hope this helps.
Jeff
 

lfansler

New Member
Thanks Jeff! I'm not sure if its possible or not, but I was hoping to geet the lights to light up randomly, one by one. Is this what the schematics are for do they light in a random pattern with several lighting at once, and can there be a control for interval between lights?
 

lfansler

New Member
I don't know how to take down the threads, this is my first time using, I apologize for any confusion. Thank you all for your help and patience
 
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R2-D2

Member
I would go with neon. A neon relaxation oscillator where each oscillator block is connected in series so that the neon bulbs interact with each other to produce truly random outputs. This is an interesting concept. Check it out:

http://www.electro-tech-online.com/custompdfs/2009/05/relaxation_oscillator_instructions.pdf

You can vary the speed of flashes for each neon by substituting much higher resistor values. I would use at least 100,000Ω pots in place of the resistors (R1, R2,...) to control the speed of flashes for each neon bulb. Just be careful with using higher voltages.

It sounds like you want any one of the eight leds to light up randomly (one by one) until all are lit up and start over again. If that's the case, you would have to go with microcontroller circuits which of course is a bit more complex. But if you just want constant random on and off flashes, I would just go with the circuit above or like the Nothing Box.
 

Technogumbo

New Member
I would seriously consider using an Arduino (Arduino - HomePage) and programming it. Although if you don't have any programming experience it may seem rough.

The development software for these boards works great on Mac and PC and you can simply program it with a USB cable.

I know one of the first programs they have as an example is blinky LED. If you take blinky LED application then use it for 8 of the ports, have a little random number generator, then turn on and off lights above or below certain numbers; you would be all set.

I hope this helps.
 
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