Randomizer Unit?

Thread Starter


Joined Sep 29, 2009
Hey guys,

Hoping someone out there might be able to come up with a solution to a problem I've been thinking about. Been straining the brain for a couple days over it lol. I'm an electrical apprentice, but don't have much to do with electronics...

But anyway, the problem: Having a house-warming party in 2 months or so (just want to get an early start on my project) and have decided on a drinking game involving a few different coloured lights. (240V power circuit lights - in Australia). Now I'm just wondering if there is any way that I can get these lights to come on in a random pattern, or if it would be easier to set a pattern myself that appears random?

The setup that I'm wanting to go with sounds something like this:
1. Fluro lights around the backyard for the main lighting
2. Every 10mins or so the fluro's switch off, and red flashing lights set up around the yard come on for roughly 10sec or so
3. Flashing lights turn off leaving a period of darkness for 2sec or so and then...
4. One of 4 pre-selected light colours (green, orange, red, or yellow) randomly turns on.
5. Circuit repeats

I have access to relays and timer relays, so I was just going to hard wire the circuit to a switchboard, I know there are probably easier ways to do this, but hey, I've got to fill in time somehow at work lol.

Any suggestions muchly appreciated.



Joined Jun 27, 2008
hi there sounds like fun, i once did something like this myself. the simplest and cheapest is probably a 555 followed by an opto isolator then triac or relay for each channel.
but in the interests of safety and simplicity have a look at something like this
a bit expensivethis one. but my home built one including case, transformer, fuses and plugs and socketsetc cost over£70


Joined Aug 15, 2007
I would use a microcontroller to generate the "pseudo-random" numbers for me. (Pseudo- because they only look random. Seed them with the same original number and the same number sequence will be generated.)

Actually, I would go with a Parallax BASIC Stamp or Arduino board or one of the other boards like them, and use optoisolators and relays to drive all 6 A.C. lines. Again, I'd look around for AC safety equipment like tibbles mentioned.


Thread Starter


Joined Sep 29, 2009
Thanks for the responses guys, I'll be sure to look into all these suggestions and probably get back on the board in a few days after I've decided on a tactic. Muchly appreciated


Joined Apr 27, 2009
Although a uC is probably the simplest way to implement all of the functionality you want in a neat package, I feel compelled to mention linear feedback shift registers, which produce pseudo-random sequences using only a shift register and some XOR gates.
That would be pretty much optimal if all you wanted to was to flash some lights "randomly". You could use a microphone with a low-pass filter and schmidt trigger as the clock, to make it switch to the beat of the music. Maybe I have to make one myself :)