The reason you're seeing a higher voltage is because you have not terminated the signal (which is OK for just detecting the presence of a signal). Normally s/pdif would be driving a 75 ohm load. SB3 uses a 3.3v logic gate driving a resistor divider. The impedance of the load combined with this output impedance results in the correct signal level of 0.5Vpp.
For the purpose of detecting any signal (assuming a hypothetical SB3 which outputs DC when idle) you would need a circuit to differentiate between DC and AC. That could be done with a diode feeding a cap to ground, and a resistor across the cap. Use that signal to drive the base of a transistor which would pull the relay coil. -- seanadams ------------------------------------------------------------------------ seanadams's Profile: http://forums.slimdevices.com/member.php?userid=3 View this thread: http://forums.slimdevices.com/showthread.php?t=43825 _______________________________________________ discuss mailing list [email protected] http://lists.slimdevices.com/lists/listinfo/discuss
