[mythtvnz] FrontEnds Controlling Audio Mains Power

[tortise]

On 2/10/2010 10:03 a.m., Tortise wrote:
> I've been thinking about automating this for some time.  I recently got a USB powered set of speakers, that refreshingly turn on and
> off (and suspend also) automagically along with the FE's status.  Works well.
>
> How do people do this for Mains powered Audio amps?   If the Amp has IR then I suppose one might successfully configure an IR
> suspend command.  (Maybe Ethernet connected Amps do WOL, but I don't know!)
>
> A few listers will recall the old AT power supplies that included a mains out socket for the monitor.  How to do it with more recent
> PS?
>
> I've been thinking about taking a USB extension lead / plug, cutting off the socket (or similar source) and feeding a relay that
> will switch 240V / 10A.  This would be nice in terms of the ease of plugging into the USB of pretty much any FE.
>
> The relay could go in some small box, also with a mains cord in and a Mains socket on the box for the Amp.  A diode would be needed
> across the coil to negate any reverse EMF.
>
> An alternative would be to use 12V from the FE power supply 12V rail, however one would need to more on the FE to make this
> available externally.   12V relays are probably cheaper and more standard however low coil current 5V relays may not be much
> different.
>
> Anyone considered anything like this?
>
>
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There is an additional complication I have realised to this idea, that 
is that some of the newer TV's when turned into standby have a two step 
process, the first step is apparent standby where they do some internal 
tidy up, saving latest freeview information and who knows what else, 
then there is the truer standby, where a relay is heard to click after 
some 45 seconds or so, and the current drawer becomes constant.

What this implies to me is that it may be preferable to have a delay 
period for the TV to do its thing of say two minutes before powering it 
off.  It also means one would have to trigger the standby mode in the 
TV.  (I am not game to see what would happen during that period if the 
power is disconnected while it is saving information?)

The TV I bought that made me realise this is a Panasonic TH-P42V20Z 
which has a LAN connection.  Maybe standby can be triggered from the 
LAN?  The documents suggests it has FreeBSD based firmware.