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It Helps If You Know Your Schmitt!

A project log for WITCH-E Decimal Based Computer

Document and create a modern replica of the Harwell Dekatron computer known as the WITCH

daves-dev-labDave's Dev Lab 02/24/2017 at 22:410 Comments

I took a quick break from "day job" work to solder on the headers for the new Transfer Interconnect Board. This first revision of this board was simply connections between the headers with no components. After working with the original design for a while and doing some scope captures it was pretty clear that i was getting a lot of signal noise and the rise/fall time of the signals was not within the required ranges for the 7400 series devices that were being connected. With that in mind i did a revision of the design adding some non-inverting schmitt triggers to the the design. oddly enough i was preparing the log post when i realized that Hackaday.com had a new post today about using schmitt triggers. The article called About Schmitt (Triggers) , has a great overview of exactly how adding schmitt triggers to this design helps with both the noise and rise/fall times of the signals.

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