Re: Slow, Automatic Light Dimmer

Ok, I realize I may have been a little harsh, but when a person is
patronized without a request for any clarification, I believe that this
is lowering oneself to a sub-par professional standard and comes off as
mere ignorance to me.

Anyway, as for your solution, that was actually the direction I was
originally headed in to begin with as I have some experience with 555
timers and RC circuits. I just stated the problem broadly as to not
limit myself to any particular foundation for design. However, as you
stated, there will likely be many people that will claim that a PIC
solution is much simpler, and I will probably succomb to the peer
pressure and follow suit, but I'd like to keep my options open at this
point.

407


PN2222A wrote:
407, man, you cut me to the quick! J***A***? This is usenet,dude. We do
have our standards.

What I'd be looking to do for this problem is this:

Zero-crossing circuit starts a timer when the line voltage is zero.
Prolly the timer's a 555 or so. At the beginning of time (your 15-minute
interval)
the timer waits 8.32msec and sends out a quick pulse.
That pulse fires the triac, turning the lamp on for a bit, until the next
zero-crossing.

As the time runs out of the hourglass, the delay drops from 8.32msec to
zero, or nearly so.

So I want a circuit that drops the trigger voltage steadily (more or less)
from some initial voltage down to zero. Typically an R-C network. Maybe
with a current source to make the ramp linear, and some low-input current
buffers.
Depends on how accurate, and how complex.

At this point, somebody will insist that it's easier to do with a PIC.
They'll be right.

PN2222A
pinout ebc, looking at the package.

.

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