I've been trying to wend my way though an optocoupler in the Aleph Current Source. One of my difficulties is that I have only a rudimentary understanding of the Aleph Current Source itself. I've read Zen Variations Part 2 a dozen times, but there are still parts I just take on faith.
In looking at some of the schematics that have been posted where an optocoupler replaces Q3 (as seen in the Zen article), I've been trying to link the sensed voltage (from R1 in the article) to a turning on of these devices. The issue for me is getting a better understanding of what factors are important for this Q3 substitution. Is Vf the main concern? Is CTR important? Does one need to tie down the base of the transistor in the optocoupler, or let it float?
I guess it's also possible the optocoupler I'm thinking about isn't in an Aleph Current source at all, but another configuration.
I've had a few very kind folks explain some of these issues to me, but I do not want to wear out their patience, so I thought I'd open this up to the forum.
Finally, if NP feels the subject matter is verboten, I'm glad to let this drop.
In looking at some of the schematics that have been posted where an optocoupler replaces Q3 (as seen in the Zen article), I've been trying to link the sensed voltage (from R1 in the article) to a turning on of these devices. The issue for me is getting a better understanding of what factors are important for this Q3 substitution. Is Vf the main concern? Is CTR important? Does one need to tie down the base of the transistor in the optocoupler, or let it float?
I guess it's also possible the optocoupler I'm thinking about isn't in an Aleph Current source at all, but another configuration.
I've had a few very kind folks explain some of these issues to me, but I do not want to wear out their patience, so I thought I'd open this up to the forum.
Finally, if NP feels the subject matter is verboten, I'm glad to let this drop.
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