Uzebox 128+

Topics regarding the Uzebox hardware/AVCore/BaseBoard (i.e: PCB, resistors, connectors, part list, schematics, hardware issues, etc.) should go here.
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D3thAdd3r
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Re: Uzebox 128+

Post by D3thAdd3r » Sun Apr 10, 2016 5:43 pm

Well, it's page 2 now. Check out the pictures just put up on the last page also.

Less thinking, more doing. I can fit the full expansion in there up next to the keyboards PCB just fine so I did. Not perfect, but not too shabby for some guy with a file. I drilled through to the underside and will run the 16 wires through a channel I made through those webs(you can see in the previous pictures) all the way to the PCB. Now there is no more second guessing since it can handle anything the standard kit can.
uze128expansion.jpg
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Heaphone jack is official I guess since the hole is cut and there should be enough room for the amp circuit either right behind it or in an unused cavity between those webs/reinforcement plastic/whatever they are called. Originally I left space for a "Uzebox 128+" logo between the controller ports and the keyboard end. Thinking about it more it seems unbalanced with all the hardware to one side and just decorations on the other half. So there will be no logo on the back, and with the potentiometer between the headphone jack and expansion port it should look quite balanced. I will possibly use a stencil and try my manual engraver to trace out things like "P1","P2","Phones","Expansion", etc if it works easy enough on a test piece of plastic.

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Re: Uzebox 128+

Post by D3thAdd3r » Tue Apr 12, 2016 1:27 am

Ordered some new keyboard and they seem they will also have the same space needed for the PCB tunnel. These are a bit more retro looking, though I might prefer the previous models aesthetics more, these are about 1/5 the price and widely available. The LT Designers run about $50+ USD now and are not very plentiful at that price even. $15 shipped for these is much nicer and there seems and endless supply. Once I know these work, there are beige versions that look the exact same mold was used for cheap.
alternatemodel.jpg
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@Alec, did you mean to imply there was some secret mouse driver in the works? That would be very very cool 8-)

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Re: Uzebox 128+

Post by D3thAdd3r » Thu Apr 14, 2016 4:33 am

Figured out the audio amp. There is a nice 3 transistor few caps and resistors discrete component version on the web which I thought was the ticket. Found prebuilt boards using surface mount that would save the work. They need the screw terminals removed for space and the potentiometer desoldered and wired to a full size one but still less than making PCBs or rigging up loose components and all that. Smaller than I was going to build too, pretty cool for the price of ~$1 each shipped. Got 10, hope they sound good.
uze128amp.jpg
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hpglow
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Re: Uzebox 128+

Post by hpglow » Thu Apr 14, 2016 5:53 am

I usually buy audio amps on aliexpess they are cheap and work well most of the time. I also like to get pwm voltage regs there.

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Flecko
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Re: Uzebox 128+

Post by Flecko » Thu Apr 14, 2016 12:50 pm

Holy crap!

Where'd you find that Audio Amp Deathadder? And what's the P/N?

I'm working on a handheld project, and after trial and error with a few different (expensive) pre-built amps, settled on one from Adafruit that still doesn't quite meet my needs.

I'd love to get my hands on some of these to test out.
Let me know when you get a chance.
Thanks!
-Flecko

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Re: Uzebox 128+

Post by D3thAdd3r » Thu Apr 14, 2016 10:17 pm

Indeed upon further research AliExpress has the best price(as usual, why do I go ebay first always!?). So now I see they can be had for $0.75 per piece, free shipping, on individual quantities if wanted. I think these are so generic there is no model but mostly just searching "LM386 board" or "LM386 mini" will bring up lots of different configurations. It seems most are geared towards monaural and not stereo so depends on what your project needs.

They also have $1.35 versions, single quantity, through hole(unassembled), shipping included(at least to NA, probably to EU also?), that have a headphone jack, a normal size potentiometer, DC barrel jack, LED, and pin headers. Seems there are a lot of different solutions for dirt cheap based on the LM386(used in Uzebox JAMMA for instance). I don't have any here yet but will report on their sound quality when they arrive.

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Re: Uzebox 128+

Post by Flecko » Fri Apr 15, 2016 1:18 pm

Even if I need to use 2 of these for stereo, it's much better than my current solution: https://www.adafruit.com/products/987

It was almost $10 + $10 shipping. And it's not the price that bothers me, but the fact that it has limited gain selection. I had a hard time finding anything that takes a potentiometer as input.

Thanks Deathadder!
-Flecko

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Re: Uzebox 128+

Post by D3thAdd3r » Mon Apr 18, 2016 2:53 am

Flecko I checked out the MAX98306 data sheet versus the LM386 and see what you mean with only 5 selectable gains. The 87396 is rated at 3.7 watts but I did not find and don't know how to calculate what the power level of the 386 actually is. Using 2 of them for stereo phones seems possible. The data sheet shows you can use a capacitor with a resistor(or potentiometer) to set gain, but if you paralleled it to make 1 pot feed 2 amps I suppose there is some electrical math involved. There is also nice examples of how to make an active "tone" control circuit to suite the frequency response of the drivers and/or personal taste in the datasheet.

I spent a bunch of time thinking about how it can be possible to have normal line level audio to the television and an amplified output for headphones. I could split the signal but I don't see a way to do that gracefully without more active components having more noise, difficulty, less precious space, or else suffering a lower audio output to the television than the standard Uzebox. The extra requirement I couldn't figure out was how to do that and also have the audio to the tv stop when headphones are inserted. I think it is not desirable to send amplified levels to the tv since there is such a small range you could actually adjust before distortion kicks in. It's not really a way to avoid using the remote to change tv volume.

I originally was working with the 5 pin jacks(these are the types mentioned herein the Uzebox portable thread) and found similar sized 11 pin ones. Couldn't find a pinout or anything but I just thought "hey 11 pins, there must be some way to do it with all those?!"
11pinjack.jpg
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So I got them and continuity tested the top 5 pins and they appeared to function just like the 5 pins version, no help there! The bottom pins traced out to be a DPDT switch, well I have plenty so I sacrificed one in the name of science just to be positive how it works, indeed they are exactly like the 5 pin versions with a DBDT switch. The act of inserting the headphones triggers the plastic blade so it is totally separate from the audio path. This is quite perfect for diverting line level audio either to the normal RCA jack or to the amplifier which connects to the headphone drivers. Well, it was a eureka moment for me since I was really lost how to do this. They are about $3 USD for 10 shipping included. They seem useful for a lot of different things.


...And the quest continues on other fronts, oh I'm hell bent on getting these things out there. I am simply unable to find a mill which is big enough to stand the keyboard up to expose the back side where the PCB connections are exposed. Mills that would be big enough are several thousand dollars and enormous, would be cool, but I can't justify something so radical right now or fit such a thing anywhere if I wanted to. The laser engraver idea I will try out, hopefully it works, but maybe it will be a waste of money who knows. I got another idea that could really make this all much easier. Instead of precision cutting all these things into the keyboard case, simply cut a nice backplate that attaches to the back of the keyboard with the proper holes in the right places. This would allow the PCB to stick slightly further out and still be flush to the (new) back alleviating the need for grinding room for the SPI ram clearance. The much much bigger thing is I could simply rough cut extra large holes for all this stuff in the keyboard and the plate could be done with a drill press mill or CNC router leaving it perfect in much less time. Next prototype on the new model keyboards I will try this!
backplate.jpg
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Re: Uzebox 128+

Post by D3thAdd3r » Fri Apr 22, 2016 1:12 am

I have the new keyboards and color matching controllers so I thought I would show some pictures for history sake. The new models aesthetically could go either way whether they are better or worse than the previous ones; personal preference really but if they are easier then they are the answer. They even come sealed in plastic with the original angled box, so they are new old stock which is nice.
u128_newmodel1.jpg
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I couldn't manage to get a picture that really shows the difference between the 2 backs. The back of the previous is much flatter than the new however. Also the parting line where the 2 halves come together is much higher in the previous one, and so for those I put the holes well below the parting line(so the top is much less modified). For these ones to work, it seems the holes will need to be cut with the case closed together and then centered on the seam. This I don't see as a problem. The curvature on the back is the only question I have, and overall is definitely a more complex shape, but it is hard to say if the PCB will still look good. I will get around to cutting the hole and see what it turns out like.
u128_newmodel2.jpg
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1 nice feature, if the curvature of the back isn't a deal breaker, there seems to be a little bit more room in the places it matters than the previous. I'm looking back at design decisions and I think it was a mistake to put the PCB on the right side. There is slightly harder clearance issues with the keyboards PCB against the Uzebox(with that model's PCB anyway) but they are actually manageable. The payoff would have been(and I suppose I didn't originally anticipate it), that the expansion would be much easier to add potentially. Basically if my eyeball measurements so far are correct, I might be able to simply cut out for a right angle header where there would not need to be any extra wires to extend it. This would significantly clean up the wiring in general.

Probably the right way to build the next prototypes is to just make a PCB that has the LM386, potentiometer, 1/8" jack, headers for On/Off, Power, Reset buttons(new better buttons I will show later), headers for the EL light, in 1 piece if it's possible to fit such a solution. This should make it much easier to build these and much less error prone. I would definitely do SMT for these due to space.

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Re: Uzebox 128+

Post by D3thAdd3r » Wed Apr 27, 2016 7:51 am

Slight update as I await more parts. With nothing else to do on it for the moment I thought more about how the mouse will integrate physically. I have 2 thoughts on it and will have to hash it around for a bit. The U128 will come with a color matching(black, black/grey, black/red) PS/2 compatible, laser mouse no matter what. This is to force aesthetic continuity and also make sure the user will have a mouse that is known compatible with the (future) firmware out of the box.

First idea is a very plain black wheel mouse with 2 buttons and scroll. These are no frills semi-generic looking logitechs but are not ugly either, $8 shipped brand new and I can probably find them cheaper. Hard to beat it's bang for the buck and I prefer solid black. As a side note there are cheap ones that have a physical scroll lock, where you can make the scroll wheel spin much more freely. This might be something desirable as a "spinner", otherwise just the normal X and Y axis that any mouse can do. For instance, in playstation 1 Tempest X3/2000, the mouse was the preferred input.

Second idea is more exciting to me. There are some wireless mice that are both optical and PS/2 compatible, but not all of them have a nice color scheme that matches. Besides this, they must be reasonably priced and available as new old stock. Also the wireless receiver must be small enough to fit in an extra cavity within the keyboard case. So far the best one that fits all this is the Logitech LX6, which I can only find in black/grey. When there is some early form of working mouse firmware I will make sure it actually works. They are available new in packaging for ~$30 but hopefully(if they test working) I can find some cheaper.
u128_lx6.jpg
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Naturally I would somehow obscure the logitech logo with just a simple "Uzebox 128+" sticker, or remove the silk screening and leave it blank. So far I have learned acetone is not a very safe method of removing silk screening...

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