Door intrusion and water level sensor

F

fubuaks

New Member

• Oct 23, 2009

• #1

I m doing this project in which the unit (microcontroller,pcb) is placed inside a cabinet.
I need a sensor for detecting any attempt of theft, as in, if anybody opens the door of the cabinet a command is send to the microcontroller.
Another sensor is required for detecting the water level, if it goes low below a certain level, the uc gets interrupted.

What kind of sensors i shud go for and where can i find theory about them?
If anybody could provide help on these two things.....

 

K

KMoffett

Well-Known Member

• Oct 23, 2009

• #2

For the door, look at magnet/reed switches like those used in home alarm systems. For the water level detector a float switch would be the simplest.

Look at how switches are interfaced to micro-controllers.

Are there any other limiting specifications?

ken

 

G

gerty

Member

• Oct 23, 2009

• #3

Here's one source for the door switch:
STANDARD MAGNETIC PROXIMITY SWITCH | AllElectronics.com
There are many others but they came to mind first.I agree with Ken on the float switch, it's the simplest.

 

F

fubuaks

New Member

• Oct 24, 2009

• #4

Thanks KMoffett and gerty for ur replies......

I searched about the reed switches and yes they are appropriate for my application. But how do i connect one to the door and its interfacing to the microcontroller...?

 

Boncuk

New Member

• Oct 24, 2009

• #5

like this.

If you require the signal inverted connect an NPN transistor between switch and MCU port pin.

 

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K

KMoffett

Well-Known Member

• Oct 24, 2009

• #6

Boncuk said:

like this.

If you require the signal inverted connect an NPN transistor between switch and MCU port pin.

Click to expand...

Or, reverse the positions of the resistor and reed switch.

Also note, when purchasing reed switches that some are normally-open (N.O.) and a magnet closes the contacts. Others are normally-closed (N.C.) and a magnet opens the contacts.


Ken

 

K

KMoffett

Well-Known Member

• Oct 24, 2009

• #7

Here are a couple of tutorials site by senior members on this form that you might find helpful.

WinPicProg Page

blueroomelectronics - Smart Kits Build Smart People

The first thing though is to determine what microcontroller you are going to use.

Ken

 

Boncuk

New Member

• Oct 24, 2009

• #8

KMoffett said:

Or, reverse the positions of the resistor and reed switch.

Ken

Click to expand...

That depends on the kind of MCU. Some only understand an active pullup, and want to see ground potential (or close to ground) when low.

Boncuk

 

F

fubuaks

New Member

• Oct 27, 2009

• #9

I am going to use atmel's 89s52.......i searched on reed and float switch, but their are many varieties of them available, which model should i go for....?my app is a simple one, so not complex one's i guess.....?

 

K

KMoffett

Well-Known Member

• Oct 28, 2009

• #10

For the float switch, you have to be specific about the water container you're monitoring. Each type of float switch works best in a specific environment. Though the "app is a simple one" the "devil is in the details". Can you give us details.

For the door switch, something like this: Directed 8600 Magnetic Micro Switch - RadioShack.com

Ken

 

B

blufke03

New Member

• Jan 7, 2010

• #11

sensors

Hello,
If you are looking for a sensor, you should visit Madison Company's website. They have a large variety of sensors, along with information on sensors so that you know exactly which sensor is right for the project that you're working on.
I hope that this helps you!

 

3

3lectrokid

Member

• Jan 7, 2010

• #12

you can just use two metal wires, a transistor and a resistor for the water level sensor