Ok, I want to do this to reduce the power consumption of my 2 desktops.
When the windows power management “turns off the monitor”, I want the signal to be repeated to a relay which in turn switches off power to the monitor/speakers/webcam/printer/scanner. The relay will basically operate a power strip to which those devices are connected.
This way when I shut down the computer, these devices will also automatically get the power off, which normally does’nt happen.
Any idea, where I can tap into this signal from ? I can amplify it and use it in the relay.
Of course, computer suppliers could do this simply by providing an outlet on the power supply, designed to do just this.
Ok, not the exact answer you’re looking for, but here’s another approach…
You could use a timer switch, and activate it everytime you leave the comp. So if your monitor is timed to go into power saving mode in, say, 15 mins., you could set the timer switch to power off in 15 mins. and activate it everytime you leave the comp. Have all your peripherals connected through this timer switch.
When the power management turns off the monitor, your computer still isn’t off. You still need to turn it off. So why don’t you just turn off the power strip when you are done?
Urban, yes the computer is not totally off. But the monitor can go into sleep mode and the hard drives can also be powered off. I just want this signal to turn off the peripherals.
If your goal is to save electricty I’m not sure you’ll accomplish it. How much power are these things consuming when they’re not being used? Aside from keeping an LED or two lit, they can’t be drawing much.
Another things is that most printers, scanners, etc. do some sort of mechanical check/calibration when they’re plugged in or turned on. They move the print head back and forth a little, spin the paper rollers… Turning them on and off might use more power (and cause more wear) than just leaving them on.
Agreed. My printer & scanner are Energy Star compliant, and probably cost pennies per year in standby. Doesn’t seem worth it.
Here is the pinout diagram for the VGA connector. I don’t think there is an on/off pin for monitor standby. Instead, I think the H and V sync signals change to set the state (on/standby/off) of the monitor, but I can’t recall the specifics. This would be difficult to sample & process.
Ok. But isn’t the power wasted a function of the power used? So, if you’re standing-by device is using very little power, only very little power is being wasted by the power supply.
I could be wrong, but I still don’t think that unplugging your power supplies will save much. And if you factor in the wear and tear that comes with power cycling your peripherals you might come out behind.
Servo, there are two kinds of power wastage. One that is constant, regardless of what is the output power and one that increases with output power. Thats why your adapter is hot even when nothing is running connected to it.
I hope I didn’t come off as challenging you, I was just curious.
I do have an idea that might work:
I don’t know how to get at the signal used to put the monitor to sleep, but here is a thread where I ask for help building a circuit to detect if my A/C is running. You could probably adapt it to detect if the monitor is on and use the output to throw a relay connected to your power strip.
They make power strips that will turn on other outlets when a device in the first outlet is turned on. Radio Shack used to sell them (at horribly inflated prices) and computer stores probably carry them as well.
Monitors just look at the sync signals, if no sync is present then they go into sleep mode. Basically you could just run the h sync through a sample and hold type circuit and use a comparitor to figure out whether or not the signal is present.
You could also use a current transformer and detect whether or not the monitor is drawing power. I’ve never opened one up, but I suspect those power outlet strips that automatically turn on other outlets when one is turned on probably just have a CT and a solid state relay inside and not much else.
If your office is lit with incandescent bulbs, replacing those with flourescents will probably make more difference than your computer peripherals. But if you really want to shut all your peripherals down, I’d just put them all into a single power bar and only switch that bar on when the peripherals are actually needed, i.e. a few minutes before a print or scan job.
More generally, if you want to save energy on all five of the listed systems (printer, scanner, monitor, speakers, webcam), put them into a single powerbar that you keep on your desk tucked neatly beside the monitor, and just get into the habit of switching this bar on or off when you start or shut down your computer. If you need to leave your computer running overnight to solve some particular problem (i.e. long download, video rendering), you can even switch off the peripherals without disturbing it.
Personally, I think if you look around your office, you can find other appliances that are wasting more energy, as in the light bulb example above. Is your office poorly air-conditioned or heated? Do you have a snack fridge somewhere that is inefficient? Is someone using a 500W halogen lamp?