Hi!

I need a device that will randomly flash a set of 7 lights (the bulbs can be
3.5 or 12 volt). I would like the on/off timing of the flashes to be random
(anywhere between up to say, 10 seconds) and for the number of lights lit
during the 'on' cycle to also be random. I really have no clue where to
start with this - would I have to build something or can I buy something
that will do the job for me?

I would be very grateful for your advice!

Thanks all,

Tim

On Wed, 03 Jan 2007 16:20:09 +0000, T J R wrote:

Hi!

I need a device that will randomly flash a set of 7 lights (the bulbs can be
3.5 or 12 volt). I would like the on/off timing of the flashes to be random
(anywhere between up to say, 10 seconds) and for the number of lights lit
during the 'on' cycle to also be random. I really have no clue where to
start with this - would I have to build something or can I buy something
that will do the job for me?

I would be very grateful for your advice!

Thanks all,

Tim


Ah, random... Like such a thing exists! bg

Question: for any given lamp, does the on-off cycle times have to be
randomized, or can they be fixed?

My first thought is that you should use a controller, but I"m probalby
making it too hard...

in article , PeterD at
wrote on 3/1/07 23:31:

On Wed, 03 Jan 2007 16:20:09 +0000, T J R wrote:

Hi!

I need a device that will randomly flash a set of 7 lights (the bulbs can be
3.5 or 12 volt). I would like the on/off timing of the flashes to be random
(anywhere between up to say, 10 seconds) and for the number of lights lit
during the 'on' cycle to also be random. I really have no clue where to
start with this - would I have to build something or can I buy something
that will do the job for me?

I would be very grateful for your advice!

Thanks all,

Tim


Ah, random... Like such a thing exists! bg

Question: for any given lamp, does the on-off cycle times have to be
randomized, or can they be fixed?

My first thought is that you should use a controller, but I"m probalby
making it too hard...



Thanks for your reply Peter.

I would like on/off cycle time to be random if possible, but don't want to
over complicate things.. so I'm happy to keep this fixed.

In regards to the device as a whole, I say random, but perhaps what I'm
looking for is something that will give an illusion of randomness?

This is whet I would do, I would use a 7447 BCD to 7 segment
decoder/driver ic to generate a pattern of flashing lights.

Use a 555 timer to generate the pulse, connected to a 7490 counter
connected to the 7447. It won't be random but you will have anywhere
from 2 to 7 lights flashing at one time.

Sal Brisindi

Thanks for your reply Peter.

I would like on/off cycle time to be random if possible, but don't want to
over complicate things.. so I'm happy to keep this fixed.

In regards to the device as a whole, I say random, but perhaps what I'm
looking for is something that will give an illusion of randomness?

This is a pretty simple task for a microcontroller. I wouldn't bother with
(pseudo) random generator, but rather just keep a list of say 50 odd numbers
that are relatively random and loop through them. You could even do
operations on the loop index to randomise the order you get numbers out of
the list.

I suspect that would produce the illusion of randomness enough for this
operation. If you really want random intervals, use a hardware 'randomness'
generator. Probably the simplest is using a reverse biased transistor to
produce avalanche noise and amplify it to drive a schmidt triggered gate.
You'd probably still need a micro to turn the lamps on and off.

You didn't say if you wanted them to come on and off sequentially or all
running continuously. If you want sequential you could use a shift register
being clocked with a variable clock, eg a 555 being triggered by a
thermistor or other noisey source. Probably not the best way to do it, but
could work.

I would use a micro, but it requires a programmer and a relatively steep
learning curve.

I'm pretty sure there would be a product available somewhere that would
fulfill you're needs, I just dunno where : )

-Tim


"T J R" wrote in message
...
in article , PeterD at
wrote on 3/1/07 23:31:

On Wed, 03 Jan 2007 16:20:09 +0000, T J R wrote:

Hi!

I need a device that will randomly flash a set of 7 lights (the bulbs
can be
3.5 or 12 volt). I would like the on/off timing of the flashes to be
random
(anywhere between up to say, 10 seconds) and for the number of lights
lit
during the 'on' cycle to also be random. I really have no clue where to
start with this - would I have to build something or can I buy
something
that will do the job for me?

I would be very grateful for your advice!

Thanks all,

Tim


Ah, random... Like such a thing exists! bg

Question: for any given lamp, does the on-off cycle times have to be
randomized, or can they be fixed?

My first thought is that you should use a controller, but I"m probalby
making it too hard...



Thanks for your reply Peter.

I would like on/off cycle time to be random if possible, but don't want to
over complicate things.. so I'm happy to keep this fixed.

In regards to the device as a whole, I say random, but perhaps what I'm
looking for is something that will give an illusion of randomness?

Thanks Sal.. But you lost me in the middle of the first sentence :-)

in article , Sal Brisindi at
wrote on 5/1/07 13:24:

This is whet I would do, I would use a 7447 BCD to 7 segment
decoder/driver ic to generate a pattern of flashing lights.

Use a 555 timer to generate the pulse, connected to a 7490 counter
connected to the 7447. It won't be random but you will have anywhere
from 2 to 7 lights flashing at one time.

Sal Brisindi

Thanks for your reply Peter.

I would like on/off cycle time to be random if possible, but don't want to
over complicate things.. so I'm happy to keep this fixed.

In regards to the device as a whole, I say random, but perhaps what I'm
looking for is something that will give an illusion of randomness?