Bandai big 1/2 BB-8 build

Dozer said:
clean job, i can't imagine how much paint it's needed to cover that beast.

Is that the final looking you want or are you planning to dirty him a bit?
Click to expand...

Not as much paint as you'd think. I'd say it's:


  • 1.5 cans of matt black
  • 2 cans of Tamiya fine primer (love that stuff)
  • 1/2 - 2/3 can of 400ml Painter's Touch Real orange (EDIT — Beware! Antsnest found this particular paint has solvents that can react with Bandai plastic. Mine likely worked because I went heavy with the Tamiya primer)
  • 1 can silver
  • 2-3 cans of white

That's still a lot of spray paint, but I've spent more on smaller projects.

It's not as clean as it looks - the friction fit of the parts takes some man-handling so there are a few scratches here and there. I'm going to weather him as per the screen prop. I'm trying to work out the process they used. It looks stippled on and lifted off, and built up in layers with a black-brown.

Here's a crop of Disney's press pack shot of BB-8 for reference:
 
Last edited:
No painting today, but the MP3 board arrived. Here it is with a small speaker I scavenged (wrong rating, just here for the proof of concept), plus a TF card I scavenged from a 10-year-old Nokia phone. The board automatically plays when it powers on and loops as well – perfect! It also remembers volume settings.
IMG_0092.JPG

So the next step was the wire an LED to the speaker via a TIP31C transistor (base = speaker positive, collector = LED ground, emitter = power ground, speaker ground, if you're wondering). Worked first time... almost. The abandoned JST connector you can see to the right is connected to the battery terminals, which are an alternative to the USB power and will actually run off 3.7v if its using a TF card. They'll power an LED when the USB is attached. However, when connecting the speaker and the LED together, it appeared to short the speaker out and I just got a rattling noise. I sort of anticipated that. Therefore, I've been running the LED off a 9v battery. I've tried a few experiments, already nearly killed the rubbish plastic speaker. I'm thinking that the circuit I'm using (just google "sound reactive LED" – several versions of it pop up) isn't going to work with a shared power source for both light and sound as surely the speaker's always going to bypass the amp to go to ground...?

Oh yeah, started making a base our of a plywood box, too!
 
Last edited:
Looking great ! The lighting and wiring seems intensive.....can't wait to see a video of the lights and sounds !


Leave it to the people here on the RPF who can make the simple task of painting a ball this difficult ! Lol
 
Two things I think I need to do to the sound circuit, which weren't in the diagram or instructions I followed. One is to put a resistor on the base of the transistor so it doesn't draw so much current and run so hot. I could also use less beefy transistor... this thing's overkill. The other is to run the speaker as normal then send a second positive cable from the board's speaker output to the transistor, then let that run from the emitter direct to ground rather than back through the board. Should work, I think
 
It's looking absolutely phenomenal. You're really making me want to get a big BB-8 now too. The lights and sound will take it to a whole other level.
 
Thanks for all the kind words :D

Good news! I stuck a 1k resistor on the base and the transistor is running cool (actually cold to the touch) and allowing the LED to run off the battery terminals. The transistor get the signal the same whether attached to the speaker outputs or run parallel from the speaker outputs on the board.

The way it works is pretty simple. The transistor forms a switch on the ground lead of the LED that turns on when enough current flows from the speaker. You still need to power the LED, which I why I've wired it to the battery terminals where it ends up in parallel to the board... it's not powered off it, it's receiving power direct from the USB connection.

It makes it quite a nice, self-contained module. I will check how much current it's drawing. I've done some calculations using a base resistor calculator, and as the LED should only use 20-30ma, I should be able to use a higher value resistor on the transistor and get the same results. As I wired the LED for 12v initially, it'll be using less. I'm keeping it as it is though as I like the dimmer light for his 'mouth'. However, I'll get my multimeter out and find out the overall draw. The LEDs were so predictable and such a doddle, it's not been out yet!
 
This is so awesome. I love all of Bandai's Star Wars kits, and it's great to see them doing something of a larger scale. Reallllly hope they expand to more characters
 
Do you have a circuit diagram for the sound-activated LED solution? I'm having a bit of trouble visualising it.
 
HughB said:
Do you have a circuit diagram for the sound-activated LED solution? I'm having a bit of trouble visualising it.
Click to expand...

I drew it out. It's from memory but it looks right. I used inspiration from a few sources like this: http://www.instructables.com/id/Sound-reactive-led-box/ There are loads of variations of it on the internet, but they don't always include base resistors so I imagine they run very hot (like mine did originally). Sorry I don't know how to draw circuits properly!

EDIT: Blown the amp on the chip one way or another, so currently investigating if there's anything up with this or if it was just through fiddling with the connections while it was on.

EDIT 2: Looks like this contains a short circuit. Got a version 2 later in the thread that I'm going to test.

sound_circuit.jpg
 
Last edited:
HughB said:
That's great, thanks! I'm looking forward to getting to work on mine...
Click to expand...

It's fun! Do consider I'm an electronics novice so that circuit likely isn't the best. A different transistor and resistor might be more suitable, but mine seems to run cool which is one of the main things, but I'm not sure if I'm putting the board at risk at all. However, at under £2 delivered, it's cheap enough to experiment with :)
 
Good news! The buck converter works a treat! Also, everything fits inside the base of the head great!

Bad news! I blew the amp in the MP3 board while trying to connect stuff while it was on (the line out still works, so it might be useful for something). I was trying to run the LED direct off the speaker out with the other speaker connected, which I'd tried before and seemed to work. However, I wonder if I was running it louder and therefore blew the thing. Before, I had it connected the speaker terminals. Electronically the same, though, I think?

Anyone got any insights looking at the diagram I posted?

Anyhow, I've ordered a couple more MP3 boards. I'm going to check the buck converter is actually outputting the right voltage before I continue.

EDIT: 12.4v going in, 5.12 coming out.

HughB said:
That's great, thanks! I'm looking forward to getting to work on mine...
Click to expand...

Yeah... don't rush into copying this circuit just yet... :)
 
Last edited:
Automaton said:
It's fun! Do consider I'm an electronics novice so that circuit likely isn't the best. A different transistor and resistor might be more suitable, but mine seems to run cool which is one of the main things, but I'm not sure if I'm putting the board at risk at all. However, at under £2 delivered, it's cheap enough to experiment with :)
Click to expand...

I'm plotting something a bit more involved with an arduino (which I've used in a lot of my projects) and a motor to rotate the head but this seems like a good way to get a sound reactive LED going (circuit refinements notwithstanding..)
 
HughB said:
I'm plotting something a bit more involved with an arduino (which I've used in a lot of my projects) and a motor to rotate the head but this seems like a good way to get a sound reactive LED going (circuit refinements notwithstanding..)
Click to expand...

I was thinking about what it would take to rotate the head. Looking at the movie footage, the base of the head including the metal trim stays put ant the top dome moves on that, which makes is simple, especially if you could 3D print a mount. Loads of room for the controller in the main body, too.

Other news: replacement MP3 board (and spare) will be with me by Monday. In the meantime, I have some Veroboard to mount the sound reactor circuit on and do a neater job. I'll stick in a 2k-ish resistor on the base and put the LED resistor on the board so the LED is easier to mount in its socket. That means I'll have three boards in there: Sound board, buck converter and sound reactor, secured with some small foam pads.

I've not figured out how I want to mount the speaker, but I might just attach it to the middle of the head base using foam pads. I've also decided to run the sound circuit parallel to everything else so I can have the lights on with no sound... I bought a second rocker switch to give me that option. I finally figured out the best way to wire that and keep the ability of removing the model from its base.
 
And here's the little circuit board I've made for the sound reactor. Much neater. JST connector for the speaker input coming out of the back. To the front, the LED and the JST connector for the power. The 1k resistor for the LED is on the board.

And here are the elements of the sound and light. Clockwise from left. 12v-5v USB buck converter (wrapped in insulating tape), short USB to Micro USB cable, MP3 decoder board with 2w amp and MicroSD card, speaker, sound reactor board (wrapped in insulating tape), LED.
 
Last edited:
Annndd....

I've tried three variations:

- Running the LED off the battery terminals. Blows the amp. Worked once, perhaps at low volume.
- Running the LED off a 9v battery. Works fine.
- Running the LED properly in parallel at 12v. Blows the amp.

I thought I'd figured out that the battery terminals were a no-go, but that wasn't the case. I've damaged all my boards in the name of science so I'm left using deduction. The 9v is higher voltage than the 5v and worked great, so I can only presume the issue is it's short circuited direct to ground without going back through the amp and that's what's blowing it.

But if that's the case, not sure how I got it to work as a one off. Perhaps I connected it wrong in a lucky accident. After blowing the first, I spotted when dismantling it that the negative battery terminal connection to the LED had come loose, which I thought I did just then but it may have been loose earlier while I was testing. Perhaps the dimmed LED and it's 15ma-or-so current (which I would expect the amp could take) was grounding via the amp rather than the battery terminal and thus not shorting?

UPDATE:

I just ran a prewired LED between the positive battery terminal and the speaker ground. Worked perfectly, although can't say what it would do to the amp. I can only presume my original inclination that running off the terminals or the main power would short the signal from the amp and my rather gung-ho experiment only worked due to the loose connection. I never thought of grounding the LED through the speaker ground to prevent the short.

Ahhhh! I'm pretty certain that's it! :D
 
Last edited:
EDIT: Here's an updated diagram of what I *think* will work and what I suspect worked before thanks to that loose connection.

circuit_v3.png

Pcoz said:
Sweet....too technical for me though. We need plug n play ! Lol
Click to expand...

Haha! It's too technical for me. See the post above :D
 
Last edited:
This thread is more than 6 years old.

Your message may be considered spam for the following reasons:

  1. This thread hasn't been active in some time. A new post in this thread might not contribute constructively to this discussion after so long.
If you wish to reply despite these issues, check the box below before replying.
Be aware that malicious compliance may result in more severe penalties.

Similar threads

COlson
Bandai 1/48 scale Snowspeeder model build with lighting
Replies
8
Views
998
stussy
stussy
COlson
Bandai 1/72 scale A-Wing starfighter build
Replies
2
Views
361
COlson
COlson
lucavigg
Bandai 1/72 Y Wing Help
Replies
8
Views
1,015
Millenniumf
Millenniumf
Millenniumf
Round 2 1:48 Eagle Transporter build
Replies
5
Views
971
Zaphod
Zaphod
Lovecrafty
Bandai 1/12 Han Solo in Stormtrooper Armour
Replies
2
Views
476
Lovecrafty
Lovecrafty
Back
Top