Re: need IC


Miroslav Pokorni
 

The 74C series was a derivative of RCA's CD4000 series (metal gate CMOS), I
believe it was matter of trademark that prevented use of 4000 designation.
Some people paid royalties to RCA but National came up with 74C and
functional equivalent designation of TTL. In the process, some DIPs did get
weird pinouts.

Regards

Miroslav Pokorni

----- Original Message -----
From: "Michael Dunn" <mdunn@cantares.on.ca>
To: <TekScopes@yahoogroups.com>
Sent: Thursday, November 06, 2003 1:51 PM
Subject: Re: [TekScopes] need IC


At 12:51 PM -0800 2003/11/6, Miroslav Pokorni wrote:
can use either package material. However, watch out that you do not get
ceramic flat pack; the 74L72 was also made in that style. Also watch that
you do not get regular TTL, 7472 (no L). They draw double current,
roughly,
and can possibly cause problem with a small scope like 212.
I'm not sure about the '72, but if I remember correctly, a lot of
L TTL had (oddly enough) different pinouts from the other varieties.
I have a vague memory of wiring up some 40085s once (some company's
name for a 74C85, which I assumed to have a standard 74_85 pinout),
and having the circuit not work too well until I rewired them as
74L85s!

Of course, if you end up subbing and rewiring, a 74HC(T) series
part might work well too...

Michael

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