Re: Historical Analog Scope Triggering Techniques


On 2020-12-04 2:31 a.m., Jeff Dutky wrote:
Okay, this is all in line with what I've been thinking about: building a little box that can raise a TTL output on various conditions like a specific counter bit, or having a 16 bit input value between two selected values, or when certain bits are set or cleared, etc. It seems like this would make all kinds of things visible on a simple analog scope at relatively little cost (assuming that you don't want to do the triggering at clock rates much above a few tens of MHz, of course).
I would consider a tiny FPGA rather than discrete TTL, which would give
you thousands of gates of logic reconfigurable without soldering. You
can get a suitable dev board for ~ $20.

One of the things that I was trying to do with these scopes, before I got side tracked having to fix them, was to reverse engineer the digital interface to a gas plasma display in an old laptop. Getting anything more than a very general look at the display signals was very challenging, especially since I didn't understand most of the scope's features very well, but also because I just wasn't thinking clearly about how to trigger the scope and one what. After working on these scopes for the past month I think I'm beginning to get a better feel for what they can do and how they should be used.

-- Jeff Dutky

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