Letter Box Monitoring and Alerting System

[jagjeet k]

I made a project based on the above idea and I thougt I would share it here. Also I am using a 9V battery to power this and the batery runs out quite fast, because of the IR transmitter I suppose. Is there any way I can make the battery last longer.

http://www.ingenstech.com/projects/letter-box-monitoring-alerting-system/

[aveekbh]

Hello Jagjeet

I see two possibilities - the LEDs and the PIC. The LEDs could be pulsed to operate, say, once in 5 seconds. The PIC - well, it depends on what it is doing all the time.

A question - what is the actual purpose of the PIC?

- A

[Wilksey]

All of these projects seem to use a base configuration in terms of hardware, I guess it's some kind of university type project store?

Anyway, is this stuff supposed to be open source as there is no source code for the PIC's on the website that I can see.

aveekbh, I guess the PIC is generating the 32khz signal for the IR and detecting when the IR beam is broken.

[Milentije]

Does PIC run all the time or it goes into sleep mode from time to time? You can do so that the PIC sleeps all the time and be awaken from sleep by IR interrupt. That way you will save a lot of energy. After the letter is recived you can blink the led every 5 seconds or so, as mentioned earlier.

EDIT:
Also, eliminate one of those "Power ON" leds and you will decrease consumption by at least 3-4 mA. BTW you have 2 LEDs for IR Tx and Rx. It should be one IR LED and one photo transistor.

You can do it with light sensor (LDR). While the letter box is closed you have one value of resistance, when the door is opened there is a change in the resistance and you can detect the event.
Ofcourse, tie the LDR to one of the pins that is capable of waking up the PIC from sleep and you are good to go.

EDIT No2:
Why do you have 7805 when you don't need it? As I can see from the schematic, after detailed look, you are using 3.3 V from LM317 for PIC. IR Tx LED isn't hooked to anything by looks of the schematic (there is no VDD net), as well as MCLR pin. You ha VDD_3.3V and VDD_5V from LM317 and 7805, but you don't have any VDD net connected to any kind of supply.
Eliminate 7805 totally, and just use 3.3 VREG to supply PIC and other components.

[aveekbh]

Wilksey, I had a closer look at the website, and, yes, it seems to be a project store.

Jagjeet, perhaps you could incorporate some of the ideas from a similar project by Ben Heck: