🚀 go-pugleaf

In article <2570007@hppad.HP.COM> lindner@hppad.HP.COM (Steffen Lindner) writes:
>I would appreciate it if any of you could help me with the following:
>
>Background Information:
>I am trying to built a digitally controlled light dimmer.  This system should
>control about 24 individual channels.  Each channel consists of one or more
>lights (incandescent).  The maximum load on each channel is about 3A.  The
>dimmer must allow a minimum of 16 brightness settings (more would be better).
>The system uses a microcontroller for I/O and triggering the TRIACs.  All
>seems well except that I have not been able to come up with a simple, cost
>effective solution to reduce (eliminate) noise.

A few years ago I built an 8-channel digitally-controlled dimmer.  I used an
8749 for the CPU, and Intel 8254 (right number??) counter/timer chips to
actually control the firing of the Triacs.  A zero-cross detector would feed
the CT chips' reset (clear?) input, a higher-frequency clock would actually
clock the CT chips, and the 8749 would load values into the CT registers,
which determined the duty cycle of the Triac-controlled load.  It worked
quite well.  The CT chips would be used in auto-reload mode, so that every
time they got a reset (clear??) from the zero-cross detector, they would
start counting again; after a programmed number of counts, they would
trigger the Triac and it would turn on for the remainder of the cycle.

mike
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