AW: AW: The merlin project. Update and tip.

[The Dark force of dance]

Y-ellow Juergen 'n' diodes.
        
At 01:15 PM 2/10/98 +0100, Haible Juergen wrote:

>Trimming (filing) in circuit would be the big deal. Imagine tuning
>a filter bank. Measure capacitors, then do some calculations
>and select resistors, or combinations of 2 resistors in series.
>Lot of measurment and calculation involved. If you can trim
>the resistors in the living circuit, just feed in a sine with the right
>frequency and file until the amplitude at the output reaches the
>peak. Same as with trimpots, only that you have better long term
>stability
>and tempco.

Not to mention a hell of a lot cheaper. :) Especially when you need to trim
a lot of them. And the idea of being able to trim them in circuit could be
particularly useful. But I also recal that there are intergrated circuits
that have their resistors trimmed up by laser. A-D's etc. Precision
multipliers and the like. They trim the circuit up by shaving off the
surface with a laser before packaging the dye. I guess it's much the same
thing. Which begs the question. "What happens to all the microscopic
material they trim off with the laser?" Perhaps it just burns away or something.

I guess there's only one way to find out if you can trim up a cap and that's
by doing it. Unfortunately I don't posess a capacitance meter of any kind. I
guess I could build up some kind of oscilator and use my counter but I'd
still have to work out how to trim it up.

If anyone's got a few spare caps and a cap meter perhaps they'd like to run
the experiment and tell us. :)

Be absolutely Icebox.
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