Want to Make my LEDs Flicker!

MythMaker

MythMaker

Active Member
Hey everyone - making these "smartwatch" props for a cosplay of the Hunter from The Division game.

The Hunters have 6 - 9 of these smartwatches on their outfits as trophies that they have taken from agents they have taken down. If you look at the video (it should start at 1:03:48) you can see how some of the watches are dead, some are steady, but most of them are flickering.
https://youtu.be/Iajv_sHhgkU?t=1h3m48s

unnamed.jpg

I made the watch to fit an LED strip inside, but now my question is, how do I get the LEDs to flicker? Is there some module I can wire in between the LED strip and the power source that will randomly flicker the lights? Similar to the lights you can get at Halloween that flicker intentionally? Thank you for any help!

~Matt Shields
 
You can get flickering LED candle lights. Don't know how well that would integrate into what you are doing, but they are definitely cheap enough to buy and experiment with.
 
Controlling the brightness of an LED electronically is typically done using Pulse Width Modulation (PWM).

You'd probably need someone to design a small circuit board with a built-in power supply and a tiny microcontroller chip running a simple PWM output.
 
Buy a flickering LED candle. Take out the LED and add it to the circuit before the LED you want to see. Cover it in tape, shrinkwrap or whatever to hide it.
Not fitted yet, but that's how my battle-damaged Endoskull's red eye flickers.
 
You can do this easily with an Arduino (as mentioned above) it is has several PWM pins you can use.

Depending on how many LEDS you have in your 'strip'... you may need to use a transistor/mosfet to toggle the current.

You can also use a 555 chip/timer.... (search google/instructables on how to implement this)

if you want to go the Arduino route.. I can help.

I'm not sure how big the watch faces are? (dimensions?)

keep in mind you also need a battery/source of some kind..

are you trying to do each watch separately? or run them all off the same battery/brain?
 
Hey MythMaker,

You mentioned in your posting that:
<snip>
"I made the watch to fit an LED strip inside, but now my question is, how do I get the LEDs to flicker?"
>snap<
Most LED strips are of the 12Vdc version so you will need a circuit that will provide the 12v needed as well as the current availability.
You didn't mention how many LEDs will be on the strip you are using or what color. That may also make a difference in your design
parameters.
How much room do you have to contain the circuit and battery supply and are you looking to have it rechargeable?

It also looks like to me that the lights in the video are blinking at random intervals and not flickering.
Flickering implies that the light has a variable brightness to it, which would require some form of modulated voltage (PWM).
Random blinking only needs a high or low signal with pseudo random time delays.

.
 
The FLORA is still just an 'Arduino' based MCU at heart in a unique form factor, and a few other features..

you can get cheaper 'clones' off ebay for roughly $2-3.00 USD..

makes it easier (cheaper) to make several 'watches' at this cost.
 
Absolutely! You can even pick up addressable LEDs (aka neopixels) on Ebay.
I only recommended the Adafruit stuff, as thats how I got started with programming LEDs and leaning to code for the Arduino and their support was fantastic.

I was looking for a way to make the engines of a model flicker, and started here: https://learn.adafruit.com/led-candles-simple-easy-cheap/overview
So the code should run on a cheaper Arduino? AWESOME! I'll have to try it some time.

Thanks xl97!

C

xl97 said:
The FLORA is still just an 'Arduino' based MCU at heart in a unique form factor, and a few other features..

you can get cheaper 'clones' off ebay for roughly $2-3.00 USD..

makes it easier (cheaper) to make several 'watches' at this cost.
Click to expand...
 
I too buy a few 'real' Arduinos and supporting shields/add-on boards to support the community...etc.

but I also pick up 3-5 pro-mini Arduinos for like $6-$10 bucks...while I picking up headers or other odds-n-ends..

makes it easy to throw them in a project and forget about them. :)
 
OMG, this is great stuff, everyone! Let me answer some of the questions:

There will be three 3-chip segments in each smartwatch, so 9 LEDS per watch (BTW, I've tested these already, should be plenty bright indoors, maybe even in sunlight!).

Each watch is about 2 1/4 inches (5.7 cm) across; pretty beefy.

I already have a battery pack with 8 AAs in there, plenty of power.

I want to have the watches hook up to the power individually, so I can disconnect or swap them out, if needed.

It would be more accurate to say that want to make some of them blink and flicker randomly, just like in the video.

I know nothing about arduinos, adafruits, but I'm eager to learn! Will start researching this and will post more progress pics soon!
 
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how much 'room' in the prop itself do you have for electronics?

Can you elaborate on this a bit more:

"There will be three 3-chip segments in each smartwatch, so 9 LEDS per watch"

* do you have leds are in these props? or can that be adjusted to whatever leds fit best for this project?

* how long do they need to be lit up for? consistently for 1 hour? consistently for 8 hours? off/on whenever you display them?



I know this is a bit out of your level of experience, but if it were 'me'

I would custom design a pcb to fit the watch back.

top side of pcb would some SMD leds in a ring pattern to light up the watch face (from under it)
bottom of pcb would have the 'arduino' bits (main MCU, voltage regulator, resistors, button..pads to connect battery)

then I would find a nice and small li-po battery that fits (more or less) under it.. so it can be sandwiched between the watch back/pcb and the clothing its being secured too.

barring that.. (for your needs) I would forego the custom PCB portion.. and use an Arduino Pro-Mini.. and see if you can use some HB (high brightness) accent leds..

the pro-mini I have in my hand measures 1.3in x 0.7in with it being 0.11in 'tall/thick' (easily covered/contained by the watch face IMHO)

it reminds me of the pcbs I made for the TASM (The Amazing Spider-Man) watch based web shooters..

challenge was to design a working pcb that fit inside (under) the watch face.

Here where I jumped in on the community/collab project and made the electronics for it:

http://www.therpf.com/showthread.php?t=152722&page=25&highlight=webshooter
nice little follow along of the progress.

Heres a quick YT vid of the pcb working:
https://www.youtube.com/watch?v=BpxKEWFCCmE




update:

I cleared out my inbox.
 
Yah... although I too like doing custom PCBs, this one works fine with each watch being a slave device (just holding LEDs) and a central controller based around a nano or similar. Because Arduino pins are generically limited to switching about 40ma, stick a heavy lifter in each watch back; the old standby power darlington is simple to set up, even if MOSFETs do run cooler (less waste). You can find hundreds of TIP120 diagrams out on the web; that's the main mark in its favor.

The nice thing about going with code -- and a central code, in this case -- is that once you get the hang of simple scripts you can tailor the effect. Have some flicker, some flash, have times when one goes dark for an interval then comes back up, etc.
 
If size becomes an issue, look into older cell phone type LED's. Way back when cell phones made phone calls people liked to customize them using different color LED's. I soldered thousands of them for the Island where everything had silly blue LED's on everything because thats what was hot at the time. We had to fit lighting into bracelets, faux tablet devices (before tablet devices existed as we now know them), office phones, what would be used as digital picture frames and everything else you can imagine. They were all these mini cell phone LED's.

If youre going strait off the shelf LED's, consider RGB. Youll also want a higher output so be prepared to tinker.
 
the only issue "I" see with the 'central network' approach is the watches then stop being modular..

and at that point or more like 'caps' to cover a cluster of leds.
 
Just saw this email, thought it may be of some interest to you/others:

http://www.instructables.com/class/Arduino-Class/?utm_source=classesNL&utm_medium=email




* what are the specs of the watch face/prop you are using? OD/ID? space under it...etc?

** (and what are the specs of the leds you have? where did you buy them?)


If you have room for a 1.25in diameter pcb.. then one of the neopixel leds rings will fit fine..

they look like this:

s-l500.jpg


you can run each with an individual arduino board and battery...

-or-

daily chain them together.....and control them -all- using one arduino..


the bonus of using these are:


pros:
they only need +5v
they only take 1 wire/pin I believe on the Arduino
you can control patterns and color at any point time if you desire.

cons:
you'll need to supply a regulated +5 voltage power source
you'll need to get one of these neopixel led rings for each 'watch' (I got mine for like $2-3.00 each)
 
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xl97 said:
the only issue "I" see with the 'central network' approach is the watches then stop being modular..

and at that point or more like 'caps' to cover a cluster of leds.
Click to expand...

Eh? I'm not sure we're defining modular in the same way. As I see it, a central unit with either "n" discrete outputs or a signal bus doesn't care if slave modules are present or not. You can drop some out, add some, whatever. (Only caveat is if you are using a daisy-chain topology to connect them -- then gotta make sure you don't break the chain).
 
may self-contained? is more accurate for you then?

you can move them wherever you want if each one had its own 'brain', leds and battery source.

I guess I'm not grasping your 'slave' approach correctly then?

Wouldnt the slave need to interpret some sort of signal/command to that tells it to blink, flicker or be solid?

(and if so, then would a stand alone approach be superior at that point?)

If by 'module/modular' you are speaking of just a 'batch/group' of leds/neopixels..


Then that goes back to my original comment about an approach with a single 'brain' (Arduino)... but if all 'modules' have to be wired together just doesnt allow the freedom the other option does.. although it would be cheaper/less work.
 
Yeah...gotcha. I'm not visualizing the complete costume here so, yeah, having to run signal wires to all of them could be a problem. (On the other hand, recharging or replacing a dozen different tiny batteries every time isn't fun either).

So I'd revise...I'd be pretty tempted to design a PCB. Because you could design a coin cell holder into it, as well as switch, and put a couple jumpers in so you can "program" the behavior individually. Free-running is also an easier way to achieve an organic offset to the flickering. And the LEDs can be surface-mounted, making the board very solid, very easy to work with, and very small.

Hrm. And now you've got me tempted. Could be a useful little board to work up...
 
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