I had a request to help an elderly friend who lives in a triplex with a shared (rural) mailbox.
He doesn't get much mail, and only wants to go (about 300-400 meter one way) to check unless there's something in there. The others grab mail on their way home from work, so anything "left over" is likely his.
My initial thought was to somehow do an initial test with an RGB led & photocell to "look at" an empty mailbox & store those settings. Then do a check whenever the mailbox is closed, if the photocell returns results (+/- some %) different from the empty box -- there's something there. (Possibly lining the mailbox with black paper or paint to easy 'see' white)
My other thought was to hack one of the cheap ebay grain-level scales and sense a weight. I tried using a force sensor, but its minimum is more than a few letters would set it off. Using the scale would be a pretty big battery drain, I think....
Either way -- send a radio signal after every mailbox close to say "Yes mail is there" or "no mail" -- so he can look at it at 6pm and know if he should go down... the radio part is simple & the spot gets lots of sun so I can use a solar charger to keep a battery charged...
Before I go trying those two -- does anyone have any (better) ideas?
IR emitter(s) in the bottom. IR receiver anywhere else. Turn on an emitter. Signal received? No mail over that one. Turn off that emitter. Turn on the next emitter. Signal received? No mail over that one. Etcetera.
The emitters should be raised slightly from the bottom to prevent dust accumulating over them. Obviously, they need to be placed so at least one is covered when the box contains mail.
Advantages: cheap; simple; with enough well placed emitters, effective; able to power-down.
However, I can't help but wonder why you have not considered the obvious solution. Ask one of the neighbors who regularly checks the box to call when the elderly friend has mail.
If possible I'd place a private mailbox first, if one of the neighbours is away for a week or forgets to check the mail every day, your friend may still walk a lot for nothing.
In my mind, the simple solution is the IR emitter, well placed.
you could put in a panel that fits the bottom of the box.
I would would offer that a second box either for his mail or sub-boxes for each person , or even a junk-mail for the rest.
could add sensors to those as well.
if the box is line of sight, you could put a narrow beam LED to show when there is mail in the box. start blinking at 6;00
the scale would be interesting as it would indicate a lot of mail.
Simpson_Jr:
If possible I'd place a private mailbox first, if one of the neighbours is away for a week or forgets to check the mail every day, your friend may still walk a lot for nothing.
Simpson_Jr:
If possible I'd place a private mailbox first, if one of the neighbours is away for a week or forgets to check the mail every day, your friend may still walk a lot for nothing.
well; he has to leave the house sometimes; so as he drives by; he can easily stop, roll down teh window & grab it... I am not certain, but I know when we wanted to move our mailbox closer (for some reason, it's a block away from us) we were told to move it to our driveway could "not be done". (or they would just ignore the new mailbox). we didn't check into further...
Thanks for the ideas!
(Today,while waiting for the wife, I had hte idea to use cheap ultrasonic distance sensors, with a timeout less than the width & height of the mailbox -- so they should read "8 inches" with nothing in it; if something is leaning against it, or on top of it, they would read "0". Essentially the IR idea, only more complicated...
The other idea I had was to make a high pitch noise, and expecting any paper in the box to dampen the noise... I think this would be problematic if it were raining hard. As I said, I like the simple IR idea.... brilliant!)