I sit in a room using my computer with my back to the door and headphones on. I'd like to be alerted when someone comes into the room by some visual indicator (or a noise in my headphones I guess!). The arrangement of the room is such that a mirror won't work.

Can anyone think of a way of doing this, ideally without trailing wires around the room? I guess some sort of door sensor or possibly a PIR sensor would be involved.

Edit based on confusion in the comments. The room is roughly an L-shape, with me in the "foot" of the L with my back to the angle, and with the door at the other end of the "back" of the L. Let's see if I can do a diagram...

|     |
|     |
|     |
|     ----------
|            |  |
|         me |  | desk
|            |  |
  • Is it your own room, or a public space? "A mirror won't work" – have you considered a free standing vanity mirror placed on the desk? – Weather Vane Mar 24 at 11:45
  • Yes, the shape of the room means there is not a direct line of sight between the desk and the door. At minimum I'd require 2 mirrors, and then getting them to line up would be a nightmare, especially as I move around my space a bit. – xorsyst Mar 24 at 12:00
  • Then you are not strictly sitting with your back to the door. The webcam answer looks good. Use wifi and have a small window in the corner of the screen that is 'always on top'. Or see here it says it can be set up to give alerts for motion detection, so you don't even need to be watching it. This is "shopping". – Weather Vane Mar 24 at 13:02
  • Kindly provide a diagram of the room showing the door and where you are located to avoid being vague. You have not provided enough detail to make a workable solution possible. Read how to phrase a question in the Help center and the Tour for our quirky site. Edit additional information into the question to avoid isolating information in comments. – Stan Mar 24 at 13:33
  • @WeatherVane as I comment in that answer, I need to use my webcam for meetings, and based on my experiments it's not possible to do that at the same time. Also, this would fail the "trailing wires" desire. – xorsyst Mar 24 at 14:27

You could get a wireless door alarm that allows you to have put it on silent and just have a visual alert, for example https://www.amazon.co.uk/Wireless-Sensor-BITIWEND-Operating-Receiver/dp/B07WMNKGCP

Similar things exist with PIR sensors

  • Brilliant, that's perfect and exactly what I need! – xorsyst Mar 27 at 18:32

At its simplest, a door hook on the inside of your door will do the job for about $2. at a hardware store. You twist the hook into one side of the door and the loop on the door frame (or vise-versa).
No tools needed.

![![wire door hook also enter image description here

… A simple request on the outside of your door.

Good luck.

  • Thanks - this would definitely work (assuming I'll hear the knock!). I'd rather I didn't have to get up in the middle of a meeting to let someone in if they need something from the room though, but so far it's the most workable suggestion! – xorsyst Mar 24 at 15:57

If you have a webcam, aim it so that the door is in view. There are many programs (including the ubiquitous Zoom) that will let you float a little webcam pane over your other windows.

  • Thank you - I had this though too, but it means I can't then actually be on meetings at the same time, which is about 25% of my job. – xorsyst Mar 24 at 12:00
  • It's impossible, then, to have both yourself and your door in the frame? – Luke Sawczak Mar 24 at 12:45
  • With a free-standing web cam :) – Weather Vane Mar 24 at 13:03

You can use two mirrors to see the door from your computer

  1. Place a small mirror to the right of your computer monitor. Angle it so that when you're facing your monitor, you can see the reflection of the wall directly behind you -- and more importantly, you can see the corner of the two walls that are behind and to the right of you.

  2. In the corner of the two walls that are behind and to the right of you, stand an upright mirror, on a 45-degree angle. It should be angled so you can see the door to your room.

In the diagram that I've included, the green dashed line represents your line of sight. The two mirrors should cost you only about $20 (at least where I live).

enter image description here

  • It even works if the door swings the other way. Curved mirrors don't even have to be aimed! – Stan Mar 24 at 15:26
  • 2
    This would work if the mirrors only worked one way! One of the reasons for this is to avoid people coming into the room seeing what I'm doing on the computer (nothing sinister, I just don't like it!) – xorsyst Mar 24 at 15:42
  • Oh, I didn't understand the privacy goal. Sorry. – BrettFromLA Mar 25 at 16:53
  • 1
    You can still do that if mirror 2 is semitransparent, or is a partially mirrored (e.g. striped) window. Have a bright, perhaps illuminated background behind the mirror on the wall facing the door, to stop people there looking at your reflection. Have a dark background on the wall facing your desk. – bdsl Apr 1 at 16:27

According to your illustration, you can solve your dilemma by turning 90° to your left and relocating your desk and relevant accessories accordingly.

Your visual alert would be caused by someone or something interrupting your visual field. No investment is necessary and no technical intervention is obvious.

The change might be refreshing. If you were facing a window, the glare reduction would be beneficial. If you were facing a wall, nothing much will be lost.

EDIT: You can create a nice background on the wall behind you for your online meetings using the money you save on unnecessary technology

Good luck.

  • Thanks, I figured someone would suggest that, but for glare and space reasons that isn't the ideal solution. – xorsyst Mar 24 at 15:40

Just lock your door.

People who want to enter would likely knock or call out. Even if they don't, trying the handle is likely to make some noise. Either way, you will be in control of when people are admitted to the room.

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