Lazyman's Switch




Introduction: Lazyman's Switch

When I go to bed every night after a hard work day I like to listen to some quiet chillout music from my pc :) But just before falling asleep every time I need to get up from my bed just when Im really comfortable ang go all across the room to stop the music and shutdown my pc...That really bugs me. So recently I started to use an app on my smartphone that can control my pc...shut it down,volume control,song change etc..wich is nice to have :) But there was one more thing... I have really sensitive hearing and I can wake up very easy.That thing is the sound coming from the speakers when they are on but there is no input signal that 50Hz hum noise coming from the mains transformer and amplifies through the speakers it's really annoying.So when my pc is shutdown remotely I need again to get up and shut down the speakers manually to get rid of the noise. So I came up with this device The Lazyman's Switch :D I will show you in these few steps how it's build and how it works :)

Exscuse my english im not very good at it.

Step 1: Materials Needed:

Extension cable (white one)

Signal wires (red and black)

Plug (eastern europe style :D)


Relay 5V(mine can handle 10A)

Small project box

Step 2: Tools Needed:

Soldering iron and solder.

Screwdrivers (Philips and a flathead)



Wire Cutters

Super glue

Electrical tape

Step 3: Cheking Voltage on PSU

First I wanted to check the 5 volt rail on my pc's psu to make sure that it will drop when the pc is shutdown because on some psu's the 5 volts still are available even when the pc is not in operation to keep feeding external devices which are on standby mode.Mine was ok so I continued.

Step 4: Soldering Signal Wires.

First I soldered the signal wires to the coil of the relay(be aware that some relays can affect and interfere with the pc's normal operation if wired directly) Mine was fine :) the other end of the wires go to the molex connector on my psu where I mesured the 5V Red and black (on the connector)

Step 5: Soldering Mains Cable.

When I mesured how much cable I will need I made a cut in one of the wires and strip the two ends of it and then soldered on the normally open contact of the relay the other one stays in one piece.So now one end of the cable goes to the plug and the other to the socket.So now when 5V is available the relay will close and let power to my speakers...but when the pc is turned off remotely from my phone it will drop the 5 volts and the speakers will shutdown and will not make the unpleasant sound... so I can be lazy :D and stay in bed.

I've also added a red indication LED.

Step 6: Putting It Together

Now everything is ready and about to go in the box.

I've glued the relay to the bottom and taped the cables and glued them too for maximum strength.

And there you have a lazyman's switch...:D

It can also control other domestic appliances like night lamps,fans,chargers and many others...a refrigerator :D (depends on relay current handling)

Hope you like it.

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