View Full Version : HP1600A Analyzer Clock

August 26th, 2013, 05:40 PM
Currently trying to use it for testing the accuracy of a paper tape reader. Need the unit to trigger and capture all eight bits of data every time the sprocket hole signal goes low (light source is shining through hole and onto phototransistor).
It seems however that the analyzer will not allow me to do much of anything unless a clock is present. It seems kind of odd that I have no way to run sans a clock and capture by trigger only.
All the documentation I have is for the 1607A which is the displayless version of the 1600A. It also just says "connect clock and be happy".

August 26th, 2013, 08:40 PM
Why not use the sprocket hole sensor as a clock?

August 27th, 2013, 11:05 AM
I am.
The idea is that (bear with me because I'm using some weird phototransistors) when the sprocket hole passes between the IR emitter and the phototransistor, the line is pulled low. When the path is blocked it's high.
I run this signal through a 2N3904 so I convert the sine wave caused from the gradual triggering of the phototransistor to a more hard edged signal the logic analyzer will work with and call a clock, then I simply tell the analyzer to reverse values and I can read in the tape to the analyzer each time the sprocket hole pulls low.

Problem is that this refined signal isn't being considered a useable clock.

August 27th, 2013, 11:53 AM
Is the problem that the "edges" aren't hard enough? If that's the case, use a 74LS14 (or even a 74LS132) that has a Schmitt trigger input to clean things up a bit. You could also do the same thing with a comparator, say a LM339.