>
>As far as David's concerns about thermal and voltage sensitivity, I was under
>the impression that many models have an optical sensor to tell you how far the
>carriage has travelled, irrespective of temp and voltage.  Perhaps I'm wrong,
>I've not used them before, just looked into using them.

Shuttle mechs have head position switches or optos.
I was talking about the burn pulse width.
You have to compensate for printhead temperature (can be as much as 2-1)
and for supply voltage, unless you print from a regulated supply.

I used a regulated supply in the one I did, which is a little tricky.
We had a 18V 2A transformer, and I needed 32V at 19A. It also had to run on
a nominal 120VAC line, down to 70V and up to 140V.

A boost switcher, with carefully designed output caps signals the processor
when it has accumulated enough energy to print the next line.

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