I thought i'd make this post as a kind of HOW-TO for anyone in the same situation as I was.
I needed to use the WOL (wake on lan) feature of my PC to access it 24/7 without leaving it on all day and night. Obviously this only works over a hardwired connection - and with me on the 4th floor and the router on the 2nd floor of my house this isn't practical so i use Devolo AV200 mini's.
After a bit of research I discovered that i should indeed be able to use WOL with homeplugs. So I set it up on the router/remote access software, put my PC to sleep, and hit the 'wake' button from my laptop, and on it comes. SUCCESS! - or i thought. Turns out, almost all Powerline adapters now have a built in standby or sleep mode that can only be awoken by activity from the PC it is connected to, not from the router side. This meant that 20mins after i put my PC to sleep, it was no longer accessible through WOL.
I called Devolo and put this to them, asking if there was any way to disable the standby or sleep mode. They confirmed that there wasn't any way to turn it off, and the only solution was to buy their 'pro' range of adapters which can be set to stay active 24/7. Me being a cheapskate I didn't want to fork out for another pair of adapters when mine work perfectly fine. I noticed the adapters can be woken up by unplugging and plugging them back in again, so this gave me an idea.
Skills required: Screwdrivering, very basic soldering. Finger nails.
Items required: Cheap mechanical plug timer, 12v-coil relay, some speaker wire (or similar)
Total cost: ~£5
Time spent: 1h (~20mins if you're not crap at soldering)
Since the adapter can be woken by unplugging/plugging in again, I needed something to cut the power and re-connect it while I wasn't there to resume a connection. I worked out that a simple mechanical plug timer would be ideal for this as they are incredibly simple and come with 15-min intervals.
By setting the timer to on-15mins, off-15mins, on-15mins etc for the whole 24h cycle, there would be a 15min window where I could wake my PC remotely. As long as the timer on the plug was set in-sync with the actual time, i would know that I could wake the PC during the 1st and 3rd quarter, and it would be turned off for the 2nd and 4th quarter of the hour.
The only problem with this was that even after I had woken my PC, the timer would still be turning the adapter on and off, only giving me 15mins of access before turning off and having to wait a further 15mins for access again.
All I needed to do was by-pass the switch inside the plug timer whilst my PC was on to keep power flowing to the adapter even after the timer was during an 'off' period. This is where the relay comes in. By using a 12V source from the PC's power supply, I can attach it to the coil of the relay, causing the relay switch to 'close' while the PC is on, and 'open' when the PC turns off. By connecting the relay to the pins of the switch in the timer, it by-passes it while the PC it turned on. Sorted!!
1) Obtaining the timer and the relay. Argos and Maplin.
2) Dismantling. Careful with the switch mech, it took me forever to work out how these went back together!!
3) These are the pins we want to 'jump' to bypass the timer switch
4) I found the best place for the relay was on the back, with holes made for the pins to sit inside the plug.
5) Gently moved the other components to access the pins better
6) Soldered some cable to the two timer pins
7) Soldered these wires to the switch-pins of the relay, and soldered some wire to the coil pins ready to attach to the PC PSU (I am SO CRAP at soldering but connections were solid). Silicone sealant went over the soldered connections just to prevent and unlikely short circuits if the pins come away, and to add strength.
8) Re-seated all the other components
9) Re-assembled the case, and set the timer for 15-min intervals (tricky they're tiny!)
10) Then I just connected the wires from the relay coil to the yellow/black of an un-used Molex from my PSU in the PC. Tested, and job done, it works great!
Since the adapter draws only a mere 0.1A in full operation, i have no concerns about power consumption or the power going through the relay switch. Its rated for 10A, though i probably wouldn't use it for anything other than the adapter.
I performed a speedtest through this connection, and there were no speed or reliability issues at all.
To improve on this mod, you could replace the resistor inside the plug that gives power to the timer motor for one with less resistance, to give the motor a higher voltage and make it spin faster. That way, the intervals would be say 5mins instead of 15mins. But I don't know the voltage limits of it, and the 15min interval is fine for what i need it for.
I hope someone finds this useful as its a really quick, easy mod to do if you use sleepy powerline adapters and really want to use WOL.