A little BANNED :-)

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IFadeToGrey
 
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Joined: Sun Oct 10, 2010 12:08 pm

Re: A little BANNED :-)

Post by IFadeToGrey »

And here's the IO/Power Supply/Codec board, minus a couple caps and inductors that I'm adding in tonight. The codec being used is the same one in earlier iPods and iPhones by Wolfson Micro. (The newer one by crystal reportedly isn't as good). The chip is pretty nice to work with, as Wolfson split the analog and digital parts of the chip right down the middle to make it easy to seperate analog and digital ground and 3.3V planes on either side of the chip.

The power supply is probably overkill at the moment (current-wise), and will probably be scaled back in future revisions after all the options are implemented, and I can be certain as to what the real current draw is going to be fully loaded. To accommodate the future-planned VCFs, it's also supplying -15 (via a Maxim 776 DC-DC circuit) and +15.

The ports on the back are (from left to right):

18VAC, Optical SPDIF In and Out RX, MIDI In, Out, and Thru, MicroSD card slot, Headphone and Mic jacks (doublestacked 1/4"), Mic gain pot, and stereo Line In and Out (doublestacked 1/4").

Image

IFadeToGrey
 
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Re: A little BANNED :-)

Post by IFadeToGrey »

Sorry to say that there haven't been any recent updates, as I've had another project that's taken priority (which is actually somewhat related), and it's been taking most all of my time, but it's almost done and I'll be getting back to this soon.

IFadeToGrey
 
Posts: 34
Joined: Sun Oct 10, 2010 12:08 pm

Re: A little BANNED :-)

Post by IFadeToGrey »

I have a quick question for anyone who'd like to share their opinion on this. I'm currently revamping this design, as the ground-plane was pretty shoddy, and I've also found some ways to make it much more affordable. My question is (for anyone who thinks they'd be interested in something like this)... Should I just surface mount all the chips/resistors/caps where possible? The benefit here is that it would be a much cleaner design, and would make the design much more feasible to have manufactured for those who aren't quite so inclined to grab a soldering iron to build something. For those who are more of the "kit builder" types, the tact switches, LEDs, headers, and other thru-hole components would still be there (and there's still quite a lot.

The other alternative is to only surface mount the FPGA/bigger chips and their associated bypass caps/pullups. This would mean that the kit would be much more elaborate for someone to build, but not really practical for those who aren't the kit builders, but who might still be interested in using it as an FPGA synth platform.

So... the question is... if this synth is something you think you're interested in... are you more interested in buying it as a kit that you can build with as many thru-hole parts as possible? Or... are you more interested in buying it as a complete product that you can dig into as a way to tweak/reverse engineer/program synthesizers?

Thanks,
Bryan

guest
 
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Joined: Fri Feb 17, 2006 5:35 am

Re: A little BANNED :-)

Post by guest »

i recently did a similar project
and the majority of people who bought it
were interested in messing with the software
so the soldering was kept to a minimum

this is mostly a tradeoff of cost though
if you are planning to do the surface mount parts yourself
then its probably best to keep that to a minimum
but if youre going to have a fab house do it for you
then the cost is pretty much fixed regardless of parts
at least to a certain extent
so you might as well get as much placed
as this reduces pcb surface area and cost
and smt parts are typically cheaper

in the case of more surface mount parts
placing breakout headers for important signals is a good idea

IFadeToGrey
 
Posts: 34
Joined: Sun Oct 10, 2010 12:08 pm

Re: A little BANNED :-)

Post by IFadeToGrey »

That's good advice. The SMDs will definitely be placed at a fab house (I have better things to do then sit there with tweezers and an aching back... lol).

With regard to breakout headers, I was more worried that I'd have to have a ton of breakout headers if the design was primarily thru-hole just for testing connectivity of the FPGA's non-memory i/o. (Memory is easy enough to test with reads and writes). The nice advantage to a "mostly" SMD design with almost all the components being pre-attached at the fab house is that it should indeed be more easily testable with far fewer headers.

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maxtim
 
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Joined: Wed Oct 12, 2005 5:01 pm

Re: A little BANNED :-)

Post by maxtim »

Nice design IFadeToGrey 8)
I would love to make something like this.
My next project, now that my x0xb0x x0xi0 tr-x0x is almost completed?
Should I just surface mount all the chips/resistors/caps where possible?
YES, SMT is way easier to work with and so much cleaner than through-hole. I would only use TH for the connectors and encoders.
With the correct tools, solders and fluxes, that DSP would be no problem to mount.
If you go for a DSP in a BGA package, then it should be pre-mounted with stencil, solder paste and automated pick-place.
the majority of people who bought it
were interested in messing with the software
I am more of a hardware than a software guy, so I guess I am in the minority of the possible interest in this project.
I will be watching your project with much interest :mrgreen:

IFadeToGrey
 
Posts: 34
Joined: Sun Oct 10, 2010 12:08 pm

Re: A little BANNED :-)

Post by IFadeToGrey »

maxtim,

I may have to ask you to do a custom case for me, just like you did for your x0x... Yours looks like some sort of unknown secret prototype from Sequential Circuits or Dave Smith that was never released. (I'm a big Sequential fan).

IFadeToGrey
 
Posts: 34
Joined: Sun Oct 10, 2010 12:08 pm

Re: A little BANNED :-)

Post by IFadeToGrey »

Hey... does anyone know of anyone other than Fatar who makes keybeds? They don't seem to be very responsive.

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