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 Post subject: Stella: Atari FB2 Pocket-Sized Portable
PostPosted: Sat Jun 12, 2010 12:14 am 
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So, when I "moved" to ModRetro, I pretty much disappeared on here. I decided to pay homage to the site that originally fathered me and post my Stella worklog here! I also noticed that some older members are returning, so perhaps I'll hop on the bandwagon. :wink:

So yeah, this portable is called Stella. Atari developers had code-named the Atari 2600 that during development, then named it the "Video Computer System" when it was released. Pretty lame in my opinion, so I'm going with Stella as the name for this portable.

Specifications:
3.5" Screen
Uses an Atari Flashback 2
Hopefully will have room for the cartridge slot
2 GBASP batteries for a total of 3.7v, 1200mAh
Uses a GBC 5v step-up to power the screen and FB2
FITS IN A POCKET! The case is what an iPod Touch comes in, and it's pretty small. The dimensions are 5x3x1-1/8".
Has built-in paddle controller.
Will have a 2nd player port
Will have a/v out

Progress so far:

Everything running sans audio amp and controller. It is actually hooked up to a GBP step-up in this photo, but it couldn't handle the amps and would get too hot. I switched to a GBC step-up. It barely gets warm.
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Preparations to chop the board up. There are a couple resistors and caps there from the 2nd player port (for the paddle controllers). They are extremely small! It tok about 15 minutes to solder them. Then I flooded them with hot glue. :P
See the middle section there? The two sides are going to be cut off leaving just the square, middle piece. It has all the important stuff.
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Case so far. The orange paint on the middle plastic piece is the color the portable will be painted.
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Comparison to a GBC:
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Tomorrow, I wet sand and paint the front half of the case. I need to buy some clear coat, paint always seems to come off of portables. Stay tuned! :mrgreen:

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 Post subject: Re: Stella: Atari FB2 Pocket-Sized Portable
PostPosted: Sat Jun 12, 2010 10:11 am 
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Like! Can't wait to see it finished.

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 Post subject: Re: Stella: Atari FB2 Pocket-Sized Portable
PostPosted: Sat Jun 12, 2010 10:20 am 
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I have the same Game Boy Color :P

I like the transparent case. Are you going to leave like this or are you going to paint it ?

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 Post subject: Re: Stella: Atari FB2 Pocket-Sized Portable
PostPosted: Sat Jun 12, 2010 10:24 am 
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Nice work; I'm glad to see you back

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 Post subject: Re: Stella: Atari FB2 Pocket-Sized Portable
PostPosted: Sat Jun 12, 2010 11:13 am 
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Bruno: It's going to be painted. If I were going to leave it transparent, I wouldn't have used hot glue like that. :P

In fact, a few minutes ago I made this to put up here:

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 Post subject: Re: Stella: Atari FB2 Pocket-Sized Portable
PostPosted: Sat Jun 12, 2010 11:28 am 
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Ok, that picture also looks amazing.

Good luck with your project :wink:

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 Post subject: Re: Stella: Atari FB2 Pocket-Sized Portable
PostPosted: Sat Jun 12, 2010 5:47 pm 
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You never cease to amaze me with your skill at taking a plain, square-ish box and turning it into something awesome. Great progress so far - what a fantastic portable! Have fun with your trace soldering 8)

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 Post subject: Re: Stella: Atari FB2 Pocket-Sized Portable
PostPosted: Sat Jun 12, 2010 10:14 pm 
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Thanks! I'm still waiting to see this finished up. :)
It's actually not too hard soldering to those traces. I got the P1 controls wired up today.

Also, the audio amp. It's based off a chip called the TDA2822N and I also used it in my Sprocket 64. It's a pretty neat little chip, with just a few external caps and resistors you can get stereo or mono out of it.

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And here's a picture I forgot to post earlier. This is the inside of the case, showing the screwposts, button boards and buttons.

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I didn't get around to painting today, I had to buy some fine sandpaper so I can sand the case so the paint will stick. I will do it tomorrow.

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 Post subject: Re: Stella: Atari FB2 Pocket-Sized Portable
PostPosted: Sun Jun 13, 2010 1:39 pm 
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First coat of paint on the front, since I don't need to put any more holes in it:
Image

I wet-sanded both halves with 600 grit sandpaper. It looks cloudy, but not scratched, so it's perfect.

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 Post subject: Re: Stella: Atari FB2 Pocket-Sized Portable
PostPosted: Sun Jun 13, 2010 2:40 pm 
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Mario wrote:
it's perfect.
I agree :D

I think I need a new FB2 to finish up my Atari portable... the controls are wonky and it doesn't seem to matter what I do to fix them. I'll get to it... sometime. Basically all that's left is swapping out the FB2's board. Everything else is done with the exception of adding batteries. Could be finished in as little as 1 hour :P

You mention that the TDA2822 can handle stereo and it appears that it can, but it looks like it needs a 10kOhm pot on each line. Is that right? I've seen stereo pots, but is there a way to handle it with a singe pot without tying the left and right channels together? I'd like to play around with using a digital pot with it but stereo digital pots are kind of hard to find. For those of you who need it, TDA2822's data sheet: http://www.st.com/stonline/books/pdf/docs/1464.pdf

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 Post subject: Re: Stella: Atari FB2 Pocket-Sized Portable
PostPosted: Sun Jun 13, 2010 10:24 pm 
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If you're looking at the stereo test circuit, those are 10k resistors to ground. But yes, if you want stereo you need a stereo pot. They aren't too hard to find if you've taken apart any old electronics. (Then again, I have two enormously overflowing boxes of old PCBs that are full of parts. It's no problem for me to find one.) That's the biggest disadvantage with this chip.
I've seen chips that have a separate volume control pin and do stereo, however. You'd have to do some searching for those.

Or, just connect the channels together. Stereo sound on a portable is overrated. :P The speakers are usually no more than 6" apart, anyway. :roll:

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 Post subject: Re: Stella: Atari FB2 Pocket-Sized Portable
PostPosted: Mon Jun 14, 2010 6:22 pm 
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Just one thing to say about BenHeck and ModRetro: ModRetro sure has a lot more activity.

So today I chopped the FB2 board up ""something fierce"" and it still works just fine.

Here is everything wired up besides the cart slot. The audio amp in the corner has a 5k pot that acts as a voltage divider for the volume control, but I was too lazy to hook it up for this test shot. :P
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Close-up of the FB2 board:
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The regulator and audio amp hooked up. I had fried my first GBC step-up because of a short, so this is a new one. Good thing I have 5 GBCs laying around. :P
Image

I put a couple more coats of paint on today, but it's still not 100% opaque. More like 89%. Tomorrow I do some more painting then I'll cover it with clear coat after 2 days.

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 Post subject: Re: Stella: Atari FB2 Pocket-Sized Portable
PostPosted: Tue Jun 15, 2010 2:23 pm 
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Will you still incorporate built-in games in addition to carts?

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 Post subject: Re: Stella: Atari FB2 Pocket-Sized Portable
PostPosted: Tue Jun 15, 2010 5:41 pm 
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Yeah, hopefully I will have enough room, as that was one of the original design ideas.

Finished painting the front, and installed the screen, audio amp, and controls:
Image

Backside:
Image

Tell me what you guys think! :D

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 Post subject: Re: Stella: Atari FB2 Pocket-Sized Portable
PostPosted: Tue Jun 15, 2010 6:22 pm 
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That is fantastic! Ben really needs to do that whole "portable of the month" thing again - this deserves it for sure! It's so perfectly... pocketable 8)

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