Tiggering a TRIAC

[FrankT]

I'm breadboarding my AC Dimmer circuit, which is basically the one on this page...

http://playground.arduino.cc/main/ACPhaseControl

I've got the zero crossing circuit/code working and I can see output on the optoisolated triac driver (MOC3052), but the main triac doesn't seem to be firing.

I've tried to simplify (see attachment) but still nothing.


What is it that fires a triac?  From what I've read, it is current into G, but the data sheets I've been reading confuse me.  I'm using a BT136-600, but I don't know what to read from the datasheet.  The freescale application note, an2839, says I should use up to 3 times the gate current. 

What am I missing?

[German_EE]

I'm not sure about that 1,5K resistor. All of the triac circuits I've seen have had large currents flowing through the device and that's what keeps the device on after it's been triggered. If you want to keep experimenting at low voltage then take out that resistor and replace it with a 12V bulb and a battery.