Another logic probe

Last Updated or created 2023-07-20

I’ve build a logic probe a while ago. (Mentioned here)

Today I got the EIStar LP-1. Its just a cheap easy probe, but does the job.
My version is only TTL and this one is TTL/CMOS (cmos is better when measuring arduino’s outputs)
TTL – Logic 1 = 4.75 -> 5V
CMOS – Logic 1 = more around the 3.3/3.7V

Only thing my version has which i’m missing is a pulse detector.
One millisecond puls gets clocked into a latch and keeps a led on.

Schematic I found (some similarities can be seen with my version)

From freeshell website

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