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

Tue Jul 2 09:35:52 EDT 2013

unfortunately the 741C is one of the few soldered IC's in my board :(


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... ;-)
>
> > 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_Amps/741_
> Pin_Compatible_Equivalent_Op_Amps.html
>
> Regards,
> Torsten
>
>
>
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>


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Long live the CoCo