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This is all great but don't underestimate these mirror displays: A friend built a similar one and disabled it when he saw the energy consumption. And this was a

by 3np 4y ago

This is all great but don't underestimate these mirror displays: A friend built a similar one and disabled it when he saw the energy consumption. And this was a few years back. Still waiting to pull the trigger on an appropriate e-paper display. At least I'd suggest to measure the setup before you commit to the whole crafts project.

criddell 4y ago
I was thinking about a similar project once and the electricity cost was about $1 / month. Am I way off on my calculations?
- ale42 4y ago
  At the current electricity prices we're paying here (~$0.35/kWh), this would be around 4 W of continuous consumption. That's not a lot, you can basically power you Pi with it, but not the screen... count at least 10x more costs to operate the screen 24h a day. But as mentioned by someone, if you use a sensor to only turn on the screen when there's someone in front of it (and if you actually turn OFF your screen when there's nobody, and not just display a black screen), then you can almost remove the display power from the equation, unless you spend your day in front of the mirror.
  - olex 4y ago
    On the Raspberry Pi, you can pretty easily switch off the HDMI output via shell commands, which sends most displays into low-power standby. It takes a couple seconds to switch back on and wake the screen when activity is detected, but the tradeoff is easily worth it.
    - axus 4y ago
      How much energy to run a microphone, waiting for "Mirror, mirror, on the wall..."
olex 4y ago
Use a PIR motion sensor to only turn on the screen when someone is around. Mine has been running for years with a 27" LCD inside, the average power use is negligible when it's in <1W standby most of the time.
rafabulsing 4y ago
I don't think an e-paper display would work in this case, though? The nature of two way mirrors requires that the screen actually emits light (instead of just reflecting it) for it to come through. Maybe an OLED panel would do the trick though, since most of the screen will be turned off. Probably much more expensive to get one of those, though.
- 3np 4y ago
  For a mirror no, for displaying the same information yes.

by 3np 4y ago

criddell 4y ago

I was thinking about a similar project once and the electricity cost was about $1 / month. Am I way off on my calculations?

ale42 4y ago
At the current electricity prices we're paying here (~$0.35/kWh), this would be around 4 W of continuous consumption. That's not a lot, you can basically power you Pi with it, but not the screen... count at least 10x more costs to operate the screen 24h a day. But as mentioned by someone, if you use a sensor to only turn on the screen when there's someone in front of it (and if you actually turn OFF your screen when there's nobody, and not just display a black screen), then you can almost remove the display power from the equation, unless you spend your day in front of the mirror.
- olex 4y ago
  On the Raspberry Pi, you can pretty easily switch off the HDMI output via shell commands, which sends most displays into low-power standby. It takes a couple seconds to switch back on and wake the screen when activity is detected, but the tradeoff is easily worth it.
  - axus 4y ago
    How much energy to run a microphone, waiting for "Mirror, mirror, on the wall..."

olex 4y ago

Use a PIR motion sensor to only turn on the screen when someone is around. Mine has been running for years with a 27" LCD inside, the average power use is negligible when it's in <1W standby most of the time.

rafabulsing 4y ago

I don't think an e-paper display would work in this case, though? The nature of two way mirrors requires that the screen actually emits light (instead of just reflecting it) for it to come through. Maybe an OLED panel would do the trick though, since most of the screen will be turned off. Probably much more expensive to get one of those, though.

3np 4y ago
For a mirror no, for displaying the same information yes.