Does anybody knows any sensor/tranduscer that detect human presence? The basic ideia is when a person aproaches his hands in a toilet the water begin to flow. When he removes his hands it stops! The sensor/tranduscer stays in the tap and goes wires to the control box!
Seems pretty pointless! I don't think any one even wants to put their hands down the toilet.
If it is a sink you are thinking of, the technology already exists. PIR sensors are used. You can buy PIR diodes for about £15 quite easily, if you find a decent supplier then I imagine the cost being an order lower.
My english it´s not to good but i think you understand my ideia...
I'm thinking to use IRA-E712ST3 (see image) that´s a pyroelectric infrared sensor and farnell price is 2.36€.
What do you think the use of this PIR in my apllication?
My english it´s not to good but i think you understand my ideia...
I'm thinking to use IRA-E712ST3 (see image) that´s a pyroelectric infrared sensor and farnell price is 2.36€.
What do you think the use of this PIR in my apllication?
You need the rest of the parts around it, plus a fresnel (I wouldn't swear that's spelt correctly!) lens to focus onto it - far easier to buy a PIR sensor ready built.
At the end of the day, If it works, it works. from memor those pyro electric devices are not very sensitive to the temperature of radiation emmited by people hands. PIR diodes are tunes for this application exactly. If you can get a 'near IR' sensor to work that's great, and cheap. But you really need a 'far IR' device to detect body heat.
As Nigel said, the secret is a fresnel-lens, it split the wiewing area of PIR sensor, and give pulses (as reply for heat-changing) on the first opamp output.