M. Adam Davis <stienman <at> gmail.com> writes:

> On 5/10/07, Peter P. <plpeter2006 <at> yahoo.com> wrote:
> > To sense high and low loads I have used two antiparallel diodes before.
> 
> This is a great idea.  Just put two diodes antiparallel to each other
> in series with the load.  There will be no voltage across them when
> there is no current drawn.  Any amount of current draw will place a
> 1.5v AC square wave across them.  Make sure they can take the load.

Actually you want to use diodes with low drop, i.e. Schottky, and you can,
because they do not need to withstand line voltage. Then by the time 2-3A are
drawn (250-350W in 110V land) they need cooling. The 0.1uF cap across them
removes switching noise and there will be a relatively nice square wave voltage
on them (about 0.8-1.2Vpp). This is not enough to light a LED but something
creative can be built from this starting point.

Peter P.


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