[Coco] XPander-Coco lives!

[Mathieu Chouinard]

Cool, add me to the list
For when they are ready for the masses
On May 25, 2016 08:47, "Zippster" <zippster278 at gmail.com> wrote:

> In trying to get one of these supervisor circuits to work in this
> application, I’ve definitely
> discovered that some CoCos are much more sensitive to having the reset
> circuit monkeyed
> with than others.
>
> Most seemed to work ok, but I had a couple of machines here that would’t
> play nice with either
> totem-pole or open-drain supervisors, resulting in continual resets (on
> some machines).
>
> Not wanting to dig into this any further, I’ve settled on a 10uF cap
> between reset and ground
> to extend reset instead of the supervisor.  This gives good reliability
> with all the machines I
> have here that I’ve tested so far, though a press of the reset button is
> sometimes needed depending
> on the machine or types of carts installed after power on.  Not a big deal
> I suppose, though I
> was trying to eliminate needing to do that with the supervisor.
>
> Anyway, they are working well enough that I’m sending one to John Strong
> so he can design a case.  :)
>
> - Ed
>
>
> > On May 1, 2016, at 7:34 PM, RETRO Innovations <go4retro at go4retro.com>
> wrote:
> >
> > On 5/1/2016 7:30 PM, Zippster wrote:
> >> I’ll look into an open drain part, the MAX811 was just what I had on
> hand patching up the boards.
> >>
> >> - Ed
> >>
> >>> On May 1, 2016, at 7:25 PM, RETRO Innovations <go4retro at go4retro.com>
> wrote:
> >>>
> >>> On 5/1/2016 6:13 PM, Zippster wrote:
> >>>> That’s a good point I didn’t give much thought to.  I know the reset
> switch works ok,
> >>>> but that doesn’t mean something else would.
> >>>>
> >>>> Since we’re working with a CPLD in the mix on these boards, I guess
> the reset
> >>>> signal to the cart ports could be routed through it, and used to
> toggle !MR on the MAX811.
> >>> I'd instead recommend an open drain supervisor, which are plentiful.
> They work the same as the MAX811, but the RESET output is open drain.
> >>>
> >>>
> >>> --
> >>> Coco mailing list
> >>> Coco at maltedmedia.com
> >>> https://pairlist5.pair.net/mailman/listinfo/coco
> >>
> > I put the following in my cart to buy:
> >
> >
> http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail&itemSeq=196005954&uq=635977197923854587
> >
> > MIC803, which seems much cheaper than the MAX811 ($.22 versus $2.10
> @100s)
> >
> > I chose a 4.38 device, but it appears MIC offers a ton of threshold
> voltages.
> >
> > Jim
> >
> >
> > --
> > RETRO Innovations, Contemporary Gear for Classic Systems
> > www.go4retro.com
> > store.go4retro.com
> >
> >
> > --
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> > Coco at maltedmedia.com
> > https://pairlist5.pair.net/mailman/listinfo/coco
>
>
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>