Simple random 'flasher' circuit - with space constraints.

[kajh]

Hiya!

I need to put together a simple light-flasher circuit to simulate 'sparking/arcing' wires. Problem I have is space constraints - I have to fit all the circuitry, power-supply and switch into two volumes: a 60mmx3mm disc and a 10mmx10mm cube.

Basically it has to fit into the model and base below and is to represent trailing wires once an arm is ripped off. The lights would hang on wires out the arm socket.

**broken link removed**

I really don't know what options are out there, so help in describing what I could do to solve this problem would be very-much appreciated! There must be pre-existing solutions already available...

Thanks for your help in advance!
Regards,
Andrew.

P.S. Apologies for the newbie question - my last analog electronics experience was decades ago.

 

[Boncuk]

You've got one option: NE556 in an SOIC-8 package and all other components also SMT.

 

[Hero999]

Buy a flashing LED, connect a suitable current limiting resistor in series and connect to a battery.

How many LEDs are there?

Do there all have to flash simultaneously?

Going by your space constraints, it sounds like a flashing LED is the only viable option.

 

[kajh]

Guys,

Thanks for the suggestion.

@Boncuk - thanks for this - I'll look up the specs. I agree surface mount will be the only way to go.

@Hero999 - I'm pretty open to the number of LEDs - just needs something which looks approximately like a sparking/arcing wire. I could get away with one flashing LED, so long as the flash was on a random cycle. Or, perhaps it flashed twice in the one cycle. Assuming I can't achieve that, I figure I could get away with two LEDs, flashing on the same period, but at different times.

That's the problem - I don't know what's out there.

re: flashing LEDs - can you get these with a random period (only ones I know are fixed period - ie. Christmas lights, et al. )

Thanks very much for your help. I have a background in digital hardware (specifically: software for digital hardware - BIOSes), but it was a long, long time ago. I'm very-much out-of-touch.

Regards,
Andrew.

 

[blueroomelectronics]

A 4017 with some diodes (to allow for pseudo random flashing) and a 555 might work.

 

[kajh]

A 4017 with some diodes (to allow for pseudo random flashing) and a 555 might work.

Yeah - would do, but I am worried about the space with the two chips - might have to head down to Tandy/Jaycar et al buy a pair to see.

Thanks!
Regards,
Andrew.

 

[kchriste]

You may be able to hack the circuit out of one of those cheap flickering LED tea lights you find at the dollar store.

 

[kajh]

You may be able to hack the circuit out of one of those cheap flickering LED tea lights you find at the dollar store.

Hahaha ... love that thinking! Very cool.

I've seen a manufacturer of these guys - URL stuck in my head for some reason: **broken link removed**

Cya,
Andrew.

 

[Hero999]

Flashing LEDs are all fixed cycle, normally about 2Hz but if you connect two or more up separately, they will drift out of phase as the frequency is poorly controlled.

What colour LEDs do you need? I assume it's white or blue?

My local supplier sells flashing blue and white flashing LEDs .
**broken link removed**

 

[Boncuk]

I thought about the two problems: random flash and space issues and came up with this idea:

Use a dual timer (NE556) and have the first one oscillate at a higher frequency than the second one. The frequency division ratio must not result in an integer value (e.g. 400/100).

The first timer resets the second one at its output frequency and the second timer is switched on only if the first timer's output goes high.

The circuit has neither been simulated nor been tested but should give a good sparking impression with the R and C values used.

The board should fit into the socket of the model you posted (0.65X0.8inches)

Regards

Boncuk

 

[MrDEB]

what about fiber optics?
perhaps put all the electronics in the base and use fiber optics for the flashing wires.

 

[transistor495]

Fibre optics lighted up using a random flashing LED is indeed a good idea...

 

[kajh]

The circuit has neither been simulated nor been tested but should give a good sparking impression with the R and C values used.

Wow! Thanks for putting so much effort into thinking about this - much appreciated! I'll take what you have as a base and will have a look at it - if nothing else, it will be a good way to brush off the cobwebs (on brain and breadboard) and get back into hardware.

Regards,
Andrew.