Random 100 LED flasher needed.

[gary350]

I want to flash 100 LEDs at random, 10 rows of LEDs, 10 LEDs per row all at random.

I have one built using NE2 neon lights. I use an RC time circuit on each light bulb 1 capacitor and 1 resistor. There is a small capacitor in parallel with each NE2. The resistor is in series between the power supply and the capacitor. Each NE2 has its own capacitor and resistor time circuit the 5% tolorance of the resistor and capacitor is enough to make the lights flash at random even though each RC circuit is identical. All the RC circuits are in parallel with a variable resistor between the power supply and the RC circuits. The power supply is a large capacitor. A throw away camera flash unit is used to charge a large capacitor from a D size flash light battery. It works great the D battery charges the large capacitor, it charges the capacitors in all the RC circuit, when the capacitor in parallel with the NE2 reaches about 65 volts it discharges through the NE2. The speed of all the flashes can be increased or decreased from about 1 flash per 5 seconds to about 1 flash per 1/10th second. Only 2 parts required per neon light.

Now I want to do the same thing with 100 LEDs. I don't have a lot of experience with LEDs I bet there is an easy way to do this??? I know LEDs are low voltage so I wonder if this can be done with 1 or 2 flashlight battery?

Every circuit I find online and in books requires a 555 timer with a lot of parts per LED or several transistors and a lot of parts just to flash 1 LED. There is a ton of circuits that will flat 50 LEDs all at the same time. This is NOT random flashing of each LED!!!! There are also 2 and 3 LED flashers that flash all 3 at exactly the same time this is not random either. There are transistor circuits that flash 2 LEDs 180 out of phase with each other this is not random either.

At the moment the only way I see to make 100 LEDs flash at random is to build 100 555 timer circuits with about 600 parts. But this does not solve the problem how to dial in a frequency change for all 100 LEDs with the turn of 1 knob.

 

[blueroomelectronics]

Flashing LEDs are about simple as it gets.

 

[gary350]

Flashing LEDs are about simple as it gets.

OK......so how is it done???

 

[MikeMl]

Red Blinking LED from Mouser. Needs external current limiting resistor.

 

[Mr RB]

Flashing LEDs are simple but you won't get the ability to "dial in a frequency change". Did you add that after people replied?

The only easy way I can think of to get 100 proper random LEDs is to use a microcontroller and some parallel register chips (to give you 100 output pins).

 

[HarveyH42]

The LEDs, with the built in flash circuit, as mentioned above, each flash at a slightly different rate. I did a 5 x 5 matrix of them, that run of solar yard light circuit. Looks fairly random... The great part is, they are very cheap, in bulk, surplus, and just wire them in parallel. They aren't overly picky about voltage, need about 3 volts for decent brightness, run fine off 6 volts, don't know the max limit though, before they burn. No resistors required to limit current.

**broken link removed**

10 cents each, isn't bad, but you can find bulk deals for half that...