possibility of making a light sensor to put in the mailbox that will make an alarm?

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aarons6
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Joined: Mon Feb 08, 2016 12:13 pm

possibility of making a light sensor to put in the mailbox that will make an alarm?

Post by aarons6 » Wed Sep 11, 2019 3:41 am

how possible is it to make a light sensor that would send an alarm to ZM when its opened?
i do have a camera facing the mailbox, unfortunately since its close to the road i cant put a motion on it to make an alarm.

it would have to be solar powered, or maybe a a rechargeable battery would last long enough..

CountyLine
Posts: 27
Joined: Thu Aug 29, 2019 5:22 pm
Location: USA

Re: possibility of making a light sensor to put in the mailbox that will make an alarm?

Post by CountyLine » Wed Sep 11, 2019 10:54 am

That's actually pretty easy. You should be able to find several designs for that sort of thing on one or more of the numerous electronics hobbyist websites.

However, I think it might be easier to set up a special zone in ZoneMinder. Just set up a small zone that would trigger on someone or something being directly in front of the mailbox. Set the Extend Alarm Frame Count to a high enough number that it would ignore passing traffic but trigger on a stopped vehicle or person.

Edit: That's not going to work. It seems that is only available to Preclusive zones. That is something I would like to see changed.

If that doesn't work, you could set up a separate monitor for the camera that looks at the mailbox. Most cameras can "talk" to multiple devices at the same time. Set this monitor's Alarm Frame Count to a high enough number and it should ignore passing cars and only trigger on stopped vehicles or persons.

In either case, you would have to be careful not to have too many frames or you might run into reference frame issues.

As a matter of fact, I think I will try something like this myself just to see how well it works.

CountyLine
Posts: 27
Joined: Thu Aug 29, 2019 5:22 pm
Location: USA

Re: possibility of making a light sensor to put in the mailbox that will make an alarm?

Post by CountyLine » Fri Sep 13, 2019 8:56 pm

Succeess! :mrgreen:

I was able to implement a monitor just for the mailbox. It triggers on a vehicle (or person) that stops by the mailbox for 3-1/2 seconds or longer. To accomplish this I did the following:

I Created an additional (second) monitor for an existing camera whose view included the mailbox in the distance. I then added a small 20 x 20 zone right next to the mailbox.

I set the Mailbox Monitor's Buffer's Alarm Frame Count to 18. Since the camera is running at 5 fps, the monitor ignores the first 3-1/2 seconds of alarm frames. Any more than that and it triggers an event. When the mail carrier stops to put mail in the box the event is recorded.

Routine vehicle traffic does not trigger an event since the vehicles cross the zone in less than 3-1/2 seconds, although very slow traffic will also trigger it. That's OK since I like to know if anyone is driving past that slowly for security reasons.

For what it's worth, this particular camera was far from ideal for monitoring the mailbox. The distance from the camera to the mailbox is 120 feet. The angle to the road is a full 45 degrees. It would be a lot easier to set up with a dedicated camera looking straight at the mailbox 90 degrees to the road.

A second monitor is required because the high Alarm Frame Count would render the camera useless for security work if there was only a single monitor. It would be preferable to have an Alarm Frame Count at the zone level instead of just at the monitor level. That would eliminate the second monitor and the extra processing overhead it requires. Perhaps that could be done, Devs?

mikb
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Joined: Mon Mar 25, 2013 12:34 pm

Re: possibility of making a light sensor to put in the mailbox that will make an alarm?

Post by mikb » Sat Sep 14, 2019 4:26 pm

aarons6 wrote:
Wed Sep 11, 2019 3:41 am
how possible is it to make a light sensor ,,, it would have to be solar powered, or maybe a a rechargeable battery would last long enough..
Is there a reason why it has to be a light sensor?

Surely the simplest answer to doing it this way is to fit a microswitch, or magnet and reed switch pair (think burglar alarm style) to the door, so when it's opened you get an opened-circuit. Requires no power supply at all -- just route the wire back from the mailbox to the house. Closed circuit = door shut.

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