SparkFun Electronics Forum

First, I am pretty to electronic.

Ok, my idea is to fix two Ultrasonic sensor at each top corner of a screen and to detect when a finder cross them and calculate the position to the screen. This way, I could build a touch screen application that will be able to press button just by getting a finder to the screen. Both sensor would been parallel to the screen pointing into the opposite down corner of the screen.

It is possible? Is there something that would not make this project works? What sensor do you recommend me?

Your going to struggle with that. Firstly the minimum distance is going to be a good distance (at best a few inches due to pulse and settle time) and then the fact that you would need a very narrow beam sensor as a typical 40kHz 18mm has about 40-45 degree angle so your X/Y positioning would be very poor.

Why not just use a normal touch screen they are cheap?

angelsix wrote:Your going to struggle with that. Firstly the minimum distance is going to be a good distance (at best a few inches due to pulse and settle time) and then the fact that you would need a very narrow beam sensor as a typical 40kHz 18mm has about 40-45 degree angle so your X/Y positioning would be very poor.

Why not just use a normal touch screen they are cheap?

I need something under 100$ for a screen about 21 inches. I do not think I can find a valuable solution that is cheap?

The biggest most commercial touches go is 19.1" and they are only £65ish (http://uk.farnell.com/higgstec/t192s-5r ... dp/1657639)