[sdiy] SSI2130

[Pete Hartman]

I was focused on " how narrow is possible" but that's a very good point.

Pete

On Sat, Sep 19, 2020 at 1:25 PM Oren Leavitt <obl64 at ix.netcom.com> wrote:

> Looks nice!
>
> Why not just go with a 0.6 inch wide DIP format? It'll fit a standard 0.6
> wide DIP socket and you'll have a little more wiggle room.
>
> It's a VCOduino!
>
> - Oren
> On 9/19/20 12:40 PM, Pete Hartman wrote:
>
> I was inspired last night to take a crack at the idea of a breakout that
> could have the chip pre-soldered.  I don't normally do a lot of work with
> finer pitch SMD so I found I had to use fairly fine traces to route to the
> pins with the chip rotated (which seemed to make the most sense, since
> going to a DIP form factor).  Necking in KiCad is not something I've
> mastered and I didn't spend a lot of time when I found it wasn't working
> the way I thought the descriptions online said it should.  PS: not looking
> for a debate about CAD packages ;).
>
> I'm curious if any of the more experienced would have any opinions they'd
> care to offer?  Full disclosure: the intent is for this to be sold as a DIY
> tool, so if providing advice for what might become a low volume commercial
> product is a concern, by all means, don't feel like you are obligated to
> comment.
>
> First the images.  I'm also sending pictures to the list for the first
> time, so if for some reason this doesn't work, I can always throw links to
> my google drive up pretty quickly.
>
> [image: Screen Shot 2020-09-19 at Sep 19 12.05.02PM.png]       [image:
> Screen Shot 2020-09-19 at Sep 19 12.06.12PM.png]
>
> I liked the idea of having the regulator(s) on board, so I dug around to
> find a couple that seemed likely.  I did find that -V regulators were
> significantly more expensive (Q100 of both of these are under $0.30,  Q10,
> and I didn't look for Q100, of even a pretty basic - regulator was on the
> order of $3.00).  Since the chips tolerates up to -18V I decided to forego
> a regulator on the negative rail.
>
> The V+ equivalent pin feeds the TLV1117-50, and that 5V feeds the
> MCP1700-25 as well as the actual V+ pin on the chip.  I figured someone
> might want to use their own different 2.5V reference so I put a normally
> closed set of jumper pads that could be cut if preferred (like the USB
> power on a teensy, for example).  This also allows you to take the 2.5V
> reference *off* the pin if you wanted to use it for expo scaling, or
> through zero, etc.  Sitting here this morning I am thinking it might be a
> good idea to provide an extra pin at the top edge so the 5V reference could
> be treated similarly.  I don't think I could do exactly the same thing
> because there has to be some way for the higher voltage to get onto the
> breakout.
>
> All the caps are 0603, which is about as small as I'd want to hand solder;
> although I do not intend to hand solder it myself, I figured leaving the
> option open even if just for prototyping seemed like a good idea.  Same
> idea behind using "handsolder" footprints for the regulator & reference.
>
> It's half an inch between the rows of pins and .7" wide by 1.7" long total.
>
> Thoughts?
>
> Thanks!
>
> Pete
>
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