<br><br><div class="gmail_quote">On 21 October 2012 07:28, tortise <span dir="ltr"><<a href="mailto:tortise@paradise.net.nz" target="_blank">tortise@paradise.net.nz</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div class="im">On 21/10/2012 3:42 a.m., DaWorm wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
Measure the current draw to your TV both when active and when off. When<br>
you turn the TV off, you can detect the decrease in current and initiate<br>
shutdown on the frontent<br>
</blockquote>
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I am not sure what advantage measuring drawn current offers over a USB rail that is either 5V or 0V? Sounds like a lot of extra electronic wizardary / complexity to achieve the same input control? (I agree it would be helpful when the monitor has no switched USB out.)<div class="im">
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<br>
> (oneshot to opto that shorts power switch<br>
> pins).<br>
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Touching the power switch momentarily, seemingly the equivalent, on my frontend does nothing. If it did tell the FE to gracefully shut down then another relay could probably be wired to achieve this.<br>
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While not all monitors / TV's give EDID responses, sensing the presence of the monitor via EDID (or somehow sensing the voltage on the USB bus?) via a cron job to gracefully turn off seems to me a good idea.<br>
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I need to read up on serial ports, however it may be a serial port can be recruited to sense the TV's 5V and use that in conjunction with CRON to cover all turn off cases (for USB switching monitors). In that event the cron job would sense for 0V and when it got 0V that would trigger a graceful shutdown.<br>
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There may be an even more KISS elegant way than this to achieve a graceful power off?<div class="im"><br>
<br>
>Same for power on, the increase in current also triggers the<br>
> oneshot.<br>
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My proposed cheap set of relay and diodes in conjunction with the FE Bios achieves power on via the TV power remote.<div class="im"><br>
<br>
>The circuit itself wouldn't draw much power but would have to<br>
> be on all the time.<br>
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Certainly that in itself would be compatible, however the relay idea draws no power when off. Only the TV standby power is then drawn.<br>
<br>
I gave some thought to using a Raspberry Pi to do similar but that also seems to duck the KISS principle...<br>
<br>
Measuring power use from these power supplies and also what is actually charged is complex and difficult to measure, because where the current is out of phase with the voltage (that is the case with the switch mode power supplies that are generally utilised in these fancy digital kit) measuring real power charged is not at all straight forward. The cheap power meters available are likely to under estimate the true position.<br>
<br>
The other scenario example I have is a Revo with a monitor and separate Amplifier connected. In that case the power to the monitor and amplifier could be even more simply controlled using a 5V Relay connected to the Revo's USB bus, that when the REVO is powered up it turns on the amplifier and monitor's mains power, and when the FE is turned off it also automatically turns them right off. Can still do remote WOL of the REVO in that configuration. Not the same as a monitor with an IR remote that was first described.<div class="HOEnZb">
<div class="h5"><br><br>
</div></div></blockquote></div>In the vein of KISS, a couple of suggestions:<div><br></div><div>In the UK you can get TV standby killers, which have an IR receiver to learn the TV off command, and then shuts off the power. These are available in multi-gang or single-gang form and readily available via the likes of Amazon and ebay. I have used these with diskless frontends and AV equipment such as DVD & receivers successfully. these also turn the power back on when the TV is turned back on<div>
<br></div><div>The other thing I have done in the past is to teach LIRC the TV off command, and tie it to the shutdown command on the frontend. </div></div><div><br></div><div>Gaz</div>