[Coco] DriveWire issues with Coco 1 F/285 Board

[Luis Antoniosi (CoCoDemus)]

but which one is pin-compatible ?



On Tue, Jul 2, 2013 at 2:31 PM, Gene Heskett <gheskett at wdtv.com> wrote:

> On Tuesday 02 July 2013 14:27:12 Luis Antoniosi (CoCoDemus) did opine:
>
> > unfortunately the 741C is one of the few soldered IC's in my board :(
> >
> Its not worth salvaging Luis, nip it off at the chip body and then you can
> unsolder it one pin at a time.  And put the next one in a gold flashed
> socket.
>
> > On Mon, Jul 1, 2013 at 7:43 AM, Torsten Dittel <OS-9 at trs-80.cc> wrote:
> > > Gene Heskett <gheskett at ...> writes:
> > > > The 741C is a very slow op-amp, incapable of doing more than a low
> > > > amplitude, slew rate limited triangular wave at 31.25 kikobaud.  Its
> > > > full gain bandwidth is only 10Hz!
> > >
> > > ...just enough for the max. 9.6 kBaud (POKE 150,1) the CoCo was
> > > designed for... ;-)
>
> Not really.  If you ever saw it on a scope, you would cringe in horror that
> it even worked.
>
> > > > Even if you have to re-arrenge the basing,
> > > > one of the op-amps in the LM35X family would be many many times more
> > > > capable a device.  The LM358, in an 8 pin minidip, actually contains
> > > > 2 fully compensated devices with .1 megacycle plus abilities at
> > > > greatly reduced power consumption.
> > >
> > > I would have to open this particular CoCo to figure out which
> > > replacement IC made it in, but it was pin-compatible (and didn't
> > > require further HW- changes), I guess one of these proposals here:
> > >
> > >
> > > http://www.petervis.com/Education/741_Pin_Compatible_Equivalent_Op_Amp
> > > s/741_ Pin_Compatible_Equivalent_Op_Amps.html
> > >
> > > Regards,
> > > Torsten
> > >
> > >
> > >
> > > --
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> > > Coco at maltedmedia.com
> > > http://five.pairlist.net/mailman/listinfo/coco
>
>
> Cheers, Gene
> --
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