From: John Popelish
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Subject: Re: job: Who can draw or send me a 1/10 second countdown timer?
Date: Thu, 05 Dec 2002 22:23:08 GMT
NNTP-Posting-Date: Thu, 05 Dec 2002 17:23:08 EST
John Woodgate wrote:
> I read in sci.electronics.design that John Popelish
> wrote (in <3DF0D25D.C182E284@rica.net>) about 'job: Who can draw or send
> me a 1/10 second countdown timer?', on Thu, 5 Dec 2002:
> >.1, .14, .2, .28, .4, .56, .8
> >1, 1.4, 2, 2.8, 4, 5.6, 8
> >These step by the square root of two, with a smaller jump at the digit
> >roll over
> >10, 12, 14, 17, 2, 2.4, 2.8, 3.4, 4, 4.8, 5.7, 6.7, 8, 9.5
> >4th root of 2 (quarter stop) steps. This decade could also be used for
> >tens of seconds and hundreds of seconds.
> >This sequence breaks the .1 second to 95 second range into only 42
> >choices, but would require a efficiently micro to hold the table of
> >times and operate the display.
Boy, I screwed that sentence up by going back and adding a word.
Should have read:
This sequence breaks the .1 second to 95 second range into only 42
choices, but would require a micro to efficiently hold the table of
times and operate the display.
> This is very sensible indeed. BUT the OP is inexperienced and advising a
> PIC is thus probably unwise.
(snip good stuff about analog solution version)
I agree that this person is not ready to do this with a PIC. He was
asking for someone to do it for him. I was just trying to get him to
think through his requirements a bit before paying someone to build
something. I have some experience with an enlarger, and I seldom went
from one extreme of exposure to the other, but tended to correct
trials by bumping the time up or down by about the square root of two
or the fourth root of two ratios. It is a real pain to have to set 3
digits on a digital timer, just to get a half stop change in
exposure. Bumping an up, down paddle is so much easier. I don't do
math well when I am thinking about composition and other visual