There are a total of ten hidden alarm clocks to be found in The Signal. You’ll know when a clock is nearby by the distanct ticking of an alarm clock. All you have to do for the clock to register as "found" is to walk up to it, and pick it up with . The achievement will unlock when you find your last clock.
Alarm Clock 1: The first alarm clock can be found in the first few minutes of going into the Oh, Deer Diner. After obtaining the flashlight and gun, go toward the entrance to the diner. There will be a large Taken that appears from the kitchen. It’s in the kitchen next to the sink.
Alarm Clock 2: Right after passing through the gate into the playground, you’ll see a few trees that have been knocked over. Jump over these trees, and the clock is sitting on a bench beneath them.
Alarm Clock 3: After trekking through the basement, you eventually come across a staircase that has the word “climb” at the top. On the opposite side of the staircase, you’ll see a chair. The alarm clock is on the chair.
Alarm Clock 4: When you first see the TV of Alan talking about the invisible Taken, continue going straight through the woods. After a bit, you’ll see a sign and an overturned train cart next to the train tracks. The clock is on the edge of the cart.
Alarm Clock 5: Traveling along the train tracks, toward the Sawmill, you’ll come across the word “Turrent.” Shine your flashlight on this word, and you’ll see that turning on the new floodlight will open up the area underneath the circus tent. The alarm clock is inside on a box.
Alarm Clock 6: You’ll come to an area where there are loads of streetlights. Continue going down the hill until you see a gap in the rocks. There is a little fence there that over-looks the final area of streetlights. Head behind the fence, and the clock is on a rock behind it.
Alarm Clock 7: When you enter the large open area of the Sawmill, you’ll see the words; “Red Box” and “Wheels.” From the entrance, continue straight. The clock is sitting on a pile of lumber near a building filled with more lumber in it.
Alarm Clock 8: You’ll come to a point where you are traveling underneath a dock. Continue on until you see the word “climb” shine your light on it, and climb upwards. Turn around, and go toward the end of the pier, and the clock is at the end.
Alarm Clock 9: After facing off against the chainsaw Taken, you’ll see a log-cabin. Off to the left of the cabin, is the clock. It is sitting up against the fence.
Alarm Clock 10: After entering Alan’s apartment, head into his office. The clock is on his lounge chair, near a lamp.