"This signal goes through two inverter circuits, creating a sharp output." The t... | Hacker News

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jonsen on Jan 7, 2018 | parent | context | favorite | on: An 8-tube module from a 1954 IBM 705 mainframe: it...

"This signal goes through two inverter circuits, creating a sharp output."

The two inverter-tubes share a common cathode resistor. This provides positive feedback from the second inverter to the first. The circuit is called a Schmitt trigger:

https://en.m.wikipedia.org/wiki/Schmitt_trigger

raverbashing on Jan 7, 2018 | [–]

And today you get 6 of them in a small package like in the 74XX derived families (74AHC14 for example)

And that's when you're doing a not so streamlined circuit, and can't have them inside your ASIC or something, if you can it gets even smaller

kens on Jan 7, 2018 | [–]

Footnote 12 in the article goes into details on the Schmitt trigger.

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