Buzzer if object is heavier than a certain weight

[koossa]

I want to start a simple hobby project, but have no idea where to start.

I just want to trigger a buzzer if anything enters an entrance heavier than a certain weight.
It don't have to be accurate, but as cheap as possible.

If someone can please point me in the right direction?

[longpole001]

Ok heres some questions for you to answer to help you define the outcomes that you may require

first

1. define the sensor type To measure the weight - assumption person will step on sensor

doing a quick google - check out sensors

http://www.kerrmedical.com/weightsensingfloormatworkswithalarmmonitors.aspx

http://www.medicalproductsdirect.com/alprmasmwese.html

simple pressure mat cant measure weight
http://www.jaycar.com.au/productView.asp?ID=LA5131


2. pick an pic which will allow a analog input , most do ,these type of mat produce a voltage relative to a weight so hooking it up is easy enough as most provide details of the interface to most alarms system they support.

get that far and it s a starting point

[koossa]

Thank you very very much, I will do some research on that!!!

[koossa]

What other types of sensors can distinguish between a large object (eg vehicle / human) and a small object, or just ignore the small objects?

[mackrackit]

What will be the maximum distance for detection?

[koossa]

Sorry for the late response.

About 2 meters

[longpole001]

some interesting sensors which may help

http://www.hokuyo-aut.jp/02sensor/

[koossa]

Great, thank you!!!