Finding Digital Logic Static Hazards

[@dioskuribackup3127]

Well explained! I really appreciate you for sharing this. Back when i studied electronics in polytechnic, the lecturers and lab assistants taught and kept reminding us to circle as many 1 in our K-map, even if it overlaps. One lecturer on digital electronics class, when asked abt this, answered that the circuit tends to be more stable if we include the extra gate (from the overlapping 1s in Kmap). It was 3years ago but just today i see the instability thanks to your video. 👍

[@madrigo]

I've been working with electronics for more than 15 years and I wish I had lessons taught to me so clear and direct. Very well done.

[@DrShaneMTU]

Thanks!! One of the reasons I'm making these videos is to hone my teaching / demo skills - so it's nice to have some affirmation!

[@MatsEngstrom]

Nicely explained. But what's the cause of the oscillation during the hazard transition time? There are no feedback loops and couldn't be a setup time violation causing metastability as in a FF, and probably not switch bounce since you had RC filters on them that should take care of it if correctly designed. So I guess it's due to slow transitions from the RC filters causing non-Schmitt inputs on the gates to act up?

[@bit2shift]

Wouldn't adding a buffer gate to the B input of BC also solve the static hazard?

[@jonathanseeley7988]

Didn't expect to see you around these parts. As far as static hazards, I didn't figure out what you were referring to until you demonstrated the issue(It appears to be an output disturbance induced by an input transition where the output would ideally remain static, but does not in practice). The topic definitely wasn't discussed in my digital logic class (not surprising, often engineering classes skip practical considerations to simplify lessons, and the professor was inexperienced). I would say as a point of feedback it would be helpful to define 'static hazard' clearly at the beginning of the video without moving directly to 'these conditions cause something with that name to occur'. It's probably fair to assume if someone does not understand this topic, then they may also be unaware what certain terms mean. Otherwise the presentation was clear. As far as what 'precision' means, I'm guessing this would impact asynchronous circuits more than synchronous circuits, and in the latter case affect settling time more than anything (unless we start to get into interference/coupling effects of this impulse perhaps present on a densely packed integrated circuit). Not necessary to dive into deeply by any means but a very short summary of scenarios where this would be a problem would also be useful. As for the oscilloscope, I'm sure you probably already figured this out but it only captured one of the pulses that I could see, might help to use a longer shutter speed. I'm guessing if you could see it with the naked eye each then the shutter speed was a shorter duration than the video frame rate.