I did wonder if the DEC 3639 part might have an integral Schotky diode, a question for DEC
..., a bit unobtanium these days but bipolar transistor + Schotky diode do / did exist -
as integrated components.
Martin
-----Original Message-----
From: Jon Elson via cctalk <cctalk(a)classiccmp.org>
Sent: 28 October 2025 19:59
To: cctalk(a)classiccmp.org
Cc: Jon Elson <elson(a)pico-systems.com>
Subject: [cctalk] Re: Replacements for DEC 3639
On 10/28/25 14:03, Martin Bishop via cctalk wrote:
Schotky diode the keep the base out of saturation ?
As used in 74S 74LS, appreciate it's an extra component to bodge in
see eg
https://electronics.stackexchange.com/questions/242715/using-a-schottk
y-diode-to-improve-pnp-transistor-turn-off-time
That's called a Baker clamp, was commonly used back in the mid '60s.
Jon