basic diac-triac phase control circuit

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "michael curtiss" <lucknau-at-yahoo-dot-com> 

Here's another schematic, which is a little simpler.


http://www.geocities-dot-com/lucknau/diac-triac_phase_control-basic.jpg

The difference between this and the circuit in my last
post


http://www.geocities-dot-com/lucknau/diac-triac_phase_control.jpg

is that the basic one is more prone to the histeresis,
or "snap back" effect caused by having to apply a high
enough voltage to get the diac to fire, which causes
C1 to drop to half voltage, initially.  I'm assuming
this levels out shortly after current is flowing, but
don't know.