Entries from February 2009 ↓

Although I’ve set my MythTV box to shutdown when not in use, we still have a constant power drain of 34 watts even when the system is turned off due to various peripherals and parasitic power drains.
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My mythtv box uses a SiliconDust HDHomeRun external network based tuner. Every so often (1 out of 5 boots) the network subsystem does not get started up before the mythtv-backend daemon. This causes an error where the mythtv-backend does not find the tuner, so it can not record any shows. Continue reading →

On my 0.21-release-fixes codebase, MythWelcome would pause for a long time (2-3 seconds) after I pressed the “MENU” key before making the menu pop up. This was because a call to “mythshutdown –status” was taking several seconds to return, and MythWelcome waited for the return value of that message before drawing the menu (It wanted to know if it should draw a “unlock” or a “lock” button.)
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2_1 – ABC
2_1 – RetroTV
5_1 – Fox
8_2 – GPB Kids
8_3 – GPB Know
11_1 – NBC
11_2 – NBC Plus (weather)
12_1 – GPB
17_1 – Peachtree TV
30_1 – PBS
34_2 – TeleFutura (Spanish)
36_1 – MyATL
43_1 – The CW
46_1 – CBS
48_0 – Univision (Spanish)
63_1 – TBN
63_2 – Church Channel
63_3 – JCTV
63_4 – Enalce
63_5 – Smile

Our MythTV entertainment system uses a decent amount of electricity. While watching TV, the television, DVD/Amplifier and computer (plus misc other items) use 335 watts of power. However, as we only average an hour or two of TV a day, this isn’t as large as the continuous power draw from the system when it is not in use. Even though we turn the TV and DVD/Amplifier off when not in use, the computer, HD Tuner, external HD, antenna preamplifier, printer, etc take up 141 watts when idle, and around 160 when recording, trans-coding, or detecting commercials in a television show. As the MythTV computer runs 24/7, this adds up to just over $10 a month of electricity (101 kW/h).

In an effort to save power, I have configured the MythTV system to shut itself off when idle, and wake up automatically five minutes before the next television show it is scheduled to record. This saves power, but has the major downside that the computer is not running and instantly ready whenever we want to watch TV. If the MythTV box isn’t already awake recording a show, you have to manually push the power button and then wait for two minutes while it boots up and gets itself ready. We are no longer able to press the TV-Power button and start watching TV five seconds later. However, this saves about 105 watts whenever the system is off (about 20-22 hours a day), or about $75-$84 a year.

We still have a constant drain of 36 watts, even when the system is turned off due to various peripherals and parasitic power drains.

• The UPS & Computer, even when turned off, takes 10 watts (Mostly the UPS keeping its battery charged).
• The external USB Hard Drive takes 8 watts.
• The printer takes 6 watts when in standby mode.
• The DVD/Amplifier, even when turned off (in standby mode) takes 5 watts of power.
• The HDTuner (Silicon Dust HDHomerun) takes 5 watts of power even when idle.
• Various other items (PDA charger, External Antenna pre-amp power injector, TV when off) take a watt each.

With the exception of the 10 watts from the UPS/Computer, the other power draws could be eliminated by using a “master-controlled” power-strip (such as the APC P7GT), which automatically turns off the controlled outlets when the computer (plugged into the master outlet) is turned off. This would save 26 watts whenever the computer was turned off, and would save about $20 worth of electricity in a year, paying for the fancy power saving power-strip in less than two years. Also, if I replaced the UPS with a “green” version, it would take less than 10 watts to keep the battery topped-up, but that cost savings would take longer to pay for itself.

We recently replaced most of our incandescent bulbs with instant-on CF light-bulbs. I cheated by upgrading our light output (using 100 watt equivalent bulbs to replace 60 watt incandescent bulbs) but each bulb should still save 34 watts.

I loosely estimated our daily light usage (over weekdays and weekends) on the newly CF fixtures as the following:

Bedroom (1 bulb): 1 hour
Bathroom (3 bulbs): 2 hours
Hallway (2 bulbs): 6 hours
Sewing Room (2 bulbs): 1.5 hour
Living Room (5 bulbs): 7 hours

We are saving (57 bulb hours * 34 watts) 1938 watts a day, approximately 2 KWh a day, or 60 KWh a month, or $6 a month (at $0.10 a KWh). We should pay for the CF light bulbs in seven months.