At 10:54 AM 12/9/96 -0600, you wrote:
 > You must be careful subbing 74 series parts here for CMOS.  This device
 >is powered
 >by stealing power from the Printer Port by using data output lines to
 >charge a cap.  Therefore VCC will never be a true 5 volts.  Depending on
 >the PC, this stolen VCC will always be less than
 >5 volts, it could fall as low as 3 volts on some PCs.  That is the reason
 >the author/designer
 >chose to use CMOS devices, because they can function on this lower
 >voltage.  74HC parts require a good solid 5 volts.

> I haven't checked my data book yet, but I thought the 74HC parts were
CMOS
> and could handle the lower Vcc.  The other 74 series may be a problem
(i.e
> Plain, LS, etc.).  I plan to add a power supply for the 5VDC anyway.  I'm
> not a big fan of stealing power from the port.
>
> Norm

I don't think you need to use 74HC parts, Digi-Key have the 40XX parts
needed
in the project.

Octavio
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