Welding

You can often buy flashing LEDs - try Maplin. Don't know if you can get them in the presumably small size you're wanting tho, if not, I might be able to rake out a basic circuit for you.

HTH, sb

Presumably what you want is a pair of flickering LEDs that come on and off intermittently for random amounts of time. If you have access to an EPROM programmer, I'd program the random intermittent sequence and flicker for the pair of LEDs into the EPROM and count through the addresses with a couple of counters, feeding the whole lot from a simple oscillator. You should probably buffer the outputs of the EPROM to drive the LEDs.

I don't know what the best flicker frequency would be (I'd guess somewhere around 15-20Hz?, which means clocking the address counter at 30-40Hz), but the whole thing would consist of:

oscillator: e.g. 7555 configured with 2 resistors + 1 capacitor as astable

16-bit counter: e.g. 2x 74HCT393 dual 4-bit binary counters EPROM : e.g. 27C512 Buffer : e.g. 7407.

As you're only using 2 bits of the possible 8 bits from the EPROM, you could have another 6 people welding at no extra cost (apart from the LEDs of course).

With a flicker frequency of 20Hz (40Hz astable clocking frequency), you should be able to get nearly 1/2 hour before the 'random' sequence repeats.

Hope this helps - let me know if you need a drawing!

Simon.

In message , snipped-for-privacy@nooo-spam-plllleeeaaassseee.yahoo.com writes

Hi sb

Yes I've got a couple of them but the on off rate is too slow, it would look better with some variation and a bit quicker. Any help would be appreciated.

TIA

I think there is a company that sells effects modules.

At in news:a9bLHsCkIfz$Ews+@fireflyuk.net, John A Calder driveled:

Try

They sell a couple of modules doing exactly what you are attempting.

-- If Your specification is vague or imprecise, you'll likely get what you asked for not what you want

Thanks Simon

Yes please and a parts list if possible, I am happy to solder bits onto PCB and veroboard etc.; and I can follow a drawing but the electronics is beyond me.

Thanks very much

In message , GbH writes

Thanks everybody

Seems to be a number of options either DIY or RTR.

Have a look at Express Models - they do a lot of lighting effects, website

HTH Jim

In article , John A Calder writes

If you're thinking in PIC terms, get yourself a 12C508 and wire the LED to one of the output pins via a suitable resistor. No other components needed, total cost of circuit (including LED) under a pound.

For the software, you're looking for a PRBS (pseudo-random binary sequence) algorithm. Wrap it in an outer loop to give bursts, something like:

REPEAT Pick a random(ish) on time (between 1 and 5 seconds) FOR that random time Output the PRBS to the LED drive NEXT Pick a random(ish) off time (between 1 and 5 seconds) Output "OFF" to the LED Wait for the random time FOREVER