??? 05/04/10 13:11 Read: times |
#175661 - You can do a lot of things... Responding to: ???'s previous message |
Arun said:
can't we use AC opto instead of two ? Of course. Arun said:
Why not use a Resistor divider and a single transistor to sense close to 0.65V? You can do a lot of things. Better opto, different resistors, etc. The circuit I have shown you is successfully used in lamp dimming applications. Whether it satifies also your needs depends entirely on you. Arun said:
how close will the zero crossing detection be (like what voltage) Vfd of led inside the opto will be around 1.8V so the positive phase detection will happen before 1.8V and negative phase detection will happen after 1.8V actual voltage zero crossing, am i correct ? The high pulse lasts about 500µsec, as I mentioned earlier. This is 250µsec in both directions from the zerro crossing, corresponding to about 4...5° phase angle. The opto stops conducting at about 25V. Kai Klaas |