AVR-Chat

On Mon, 16 Jul 2007 14:33:44 +0200 (CEST) you wrote:

>Hello folks,
>
>I have a 230 V AC power line that is connected to a light dimmer. I want
>to determine how much this signal is dimmed, e.g. what the duty cycle is
>(i guess the dimmer regulates the duty cycle?). 8-Bit precision is enough
>(or less as well)
>
>Any suggestions how to connect the power line to the microcontroller?
>
>My first thought was to connect a resistor and zener diode in series and
>an optocoupler over the diode, thereby making it possible to read the
>value from the other side of the optocoupler, but all optocouplers seems
>to need at least 20 mA through the led which would make the resistor
>suffer 4.5 watts...
>
>Regards,
>
>Manne Tallmarken

In practice a lot of optocouplers will function with a lot less than 20mA. In
one circuit I use an SFH601-4 at only 2mA.
--
Ralph Hilton
http://www.ralphhilton.org
C-Meter: http://www.cmeter.org
FZAOINT http://www.fzaoint.net