ultrasound device

Hello everybody,

I am looking for a circuit that can alert me if my daughter, while she is playing outside, get too far.

I am thinking to use ultrasound. A device *A* that send a ultrasound signal and a device *B* answer with ultrasound when it get the signal signal from *A*. The distance can be calculated when the device *A* receive the signal back from the device *B*.

I have no time to create everything from scratch and I am wondering if somebody can help to find some electronic schema ready to use or with only some adaptations. Obviously, the device *B* need to be small. I Google a lot and search this site also without finding anything.

Thanks in advance.

yvesfra said:

I have no time to create everything from scratch and I am wondering if somebody can help to find some electronic schema ready to use or with only some adaptations. Obviously, the device *B* need to be small. I Google a lot and search this site also without finding anything.

Click to expand...

You'd be better off then using a ready made device like this :

https://www.amazon.co.uk/Mummy-Stay...TEL6/ref=sr_1_1?ie=UTF8&qid=1348316739&sr=8-1

Yes, a ready made device would make FAR more sense (and it needs to be RF not ultrasonic) - you also need to be aware of the limitations of such devices, accuracy is low, and false triggers common.

I didn't know such devices exist.

Thanks a lot picbits (and Nigel Goodwin).