??? 05/05/10 08:13 Read: times |
#175697 - sorry Responding to: ???'s previous message |
i didnt read all posts. Finally i understanded, :-)
;------------ Then again - Your SMPS is nice thing , and - in my opinion - is not "compatible" in terms of quality and elegance - with 1_Resistor_ZCD. I prefer optoisolator here. Non-isolated ZCD means You will connect micro's GND or VCC to Neutral or Live wire. Last case needs care. Thalking about bad quality of mains , You must take some prevantive actions in hardware and software , and check it against worst case. Here i think 2-optoisolator circuit ,proposed by K.Kaas, is good starting point. And many IF-THEN-ELSE in software - against false signals. ;----------------------- 3 wire is supercomfortable environment :-) . ;----------------------- 500 W is nothing special . ;----------------------- "8 steps of brightness" - i suppose You will come to user selectable brightnes, which means more than 8 steps . Or 2 differet modes - with 8 steps and with smooth kontrol. ;----------------------- Single transistor ZCD , or single optoisolator ZCD - difference is only in safety , some cost , and simplicity/complexity in software . If You prefer, let talk about transistor, without isolation. 250VAC 1Mohm gives 0.044W , so resistor size is determined only by 250V requirement. One end of resistor is connected to Live, other to small MOSFET's gate. MOSFET's source is connected to micro's GND , which is tied to Neutral.Between gate and source will be one zener diode 5..6V ,with anode to GND.Drain is connected to micro. This is my proposal :-) . best regards |