Drentsoft Doorbell Early Warning System is a hardware/software system for determining both when to answer the doorbell and knowing when the postman's arrived with your precious postal goodies.
There are times when you just don't want to answer the door for whatever reason be it you're in the middle of something, you're not feeling well, you think it'll be a waste of your time etc. With the Drentsoft Doorbell Early Warning System you can decide ahead of time whether the person approaching the door is worth your time and effort. Think of it like a predictive intercom without the interaction.
Yes and no. Put it this way, think of your poor grandparents, knees aching, they spend all their time upstairs where the house is warmest. Someone rings the doorbell and by the time they've managed to creak their way downstairs the ringer has got bored and left r maybe they're some overly aggressive door to door salesperson who won't take no for an answer.
Now imagine if they'd had a system like this where an image of the person is sent to the nearest computer and they can decide whether it's worth their effort.
This might seem a little far-fetched as retirees are probably the least likely demographic to be sat next to a computer/smart device when their doorbell is rung but it's not beyond the realm of possibility. Smartphones are making people more and more interconnected and many grandparents are being setup with smartphones so they can perform VOIP calls with their distant relatives, live and with video. Why couldn't they install an app on their phone that improves their lives even more.
OK, not satisfied? What about these.
You're waiting desperately for the postman to deliver your latest prized possession but he often doesn't deliver at the same time every day. If you're upstairs you'd be running up and down all morning/afternoon or straining your poor ears waiting for the sweet sound of "droppage".
Or not, you're busy working at your desk when a window pops up and WOW! It's the postman!
You've now freed up your morning for useful work and still have the delight of picking up freshly delivered goodies.
Disclaimer: OK, this might not be that useful for everyone but as someone self-employed who mostly works from home it's a really serious issue!!
Client computers/phones/tablets connect to a network/internet enabled Raspberry Pi server.
PIR motion sensor triggers the Raspberry Pi camera module, taking a few snapshots of the approaching doorbell ringer.
The Raspberry Pi, being connected to your network (and possibly DNS'd to the greater internet) sends the images to all connected clients.
The clients receive the images and can quickly decide what to do about the person at the door (ignore/run down etc)
The biggest issue at the moment is how to power the Pi.
Disclaimer: All prices are approximate and are subject to change by the various suppliers.
These may seem a little steep but first off the Pi will be connected to your network so you could always SSH into it and do other cool things when you don't think you'll need the doorbell monitor. You could also only mount it on days when you're expecting a high level of footfall, for example days when you're expecting a workman or on a day that you've taken off work to wait in for a delivery.
As this is still very much an experimental concept at the moment I shall be using a model B Raspberry Pi that I can use for other purposes if this project doesn't work out. The idea being that I can always switch to a lower powered model A if I decide to make this a permanent setup.
I have a porch between my front door and the doorbell so for my purposes any old case will do as long as I can find some way of mounting the case to the brick outer wall. I'm tempted to go for the Cyntech case sold by Mod My Pi for £6.99 as it has screw mounting holes on the underside.
The Raspberry Pi camera module is basically a given, one could maybe use a USB webcam but it would require the use of a model B for the 2 USB ports or a powered USB hub, which would make the power situation that much more complicated again.
I think the Tandy PIR sensor makes the most sense as it outputs the correct voltage for the Raspberry Pi GPIO and accepts input voltages that the Pi can supply and at £3.99 + £1 postage (at time of writing) this seems reasonable especially weighing up the delivery times for the eBay ones.
The Raspberry Pi server could also connected to an LCD near the doorbell, a receiving client can then send one of several messages such as:
The LCD can also be used to tell the person at the door about the doorbell position if it's hard to find
The LCD could be combined with a couple of flashing LEDs to draw attention to it
For a fun coding exercise, get rid of the need for the PIR and use the camera itself as the motion detecting sensor.
Upon further research I have discovered the most PIR sensors won't be able to penetrate glass. I had assumed that most household alarm motion sensors simply didn't pick up on motion through windows because they were designed to have a range that was just long enough for the average sized room with the majority of the power dissipating against the window.
For most people who would mount their doorbell monitor outside, not a whole lot but I had planned on mounting everything inside the porch, a mostly glass structure. This leaves me with 3 options.
I hope I've at least given someone some sort of inspiration for projects that could be done with the Raspberry Pi even if they think this design is too expensive to be of any practical use. I've had another idea for a web enabled security camera using the Pi and the camera module that takes pictures of hooligans if they stay near the house causing problems too long. More on this on its own page soon.