kenanizmirli

is there anybody who knows to do a color sensor circuit by using cny 70? please help me...

Nigel Goodwin

I can only suggest you use coloured filters, a different one for each colour.

kenanizmirli

you mean for three color sensing three cny 70 right? but i need to do it with one cny 70,
does anybody know its working principle?

Nigel Goodwin

You could either do it with three cny70's and three filters, or one cny70 and rotate the different filters in front of it.

There's no way to detect different colours otherwise - the cny70 is just a reflective opto-switch - it sends a beam of light out and looks for the reflection coming back. Different colours will reflect slightly differently, but I doubt you could accurately distinguish between them (and shades of grey would do exactly the same).

Why do you want to detect different colours?.

kenanizmirli

for a project i need to seperate three different colors. i have a simple circuit with one cny 70, but it doesn`t work well, i mean it gives the same values for green and orange, only black has different value... does it help me to use colors that are in different place in color spectrum?

Nigel Goodwin

It's the same problem as wanting to use a B/W camera to give colour pictures - the sensor used has no way of distinguishing colours, so there's not much you can do about it. The three coloured filter trick was used on old Amiga picture digitisers - they supplied a four colour disk to mount in front of a B/W camera, clear, red, blue and green. To get a colour picture you had to take three samples, with each of the coloured filters in front of the camera. The picture quality was very good, as you are essentially using an RGB camera.

The sensor itself is designed to give a simple response of reflection or no reflection, basically white gives reflection, and black gives no reflection. In between these two points there are various shades of grey, which will give varying amounts of reflection - if the sensor can provide an analogue output, it may be possible to detect a few shades of grey - but it's highly dependent on many variables.

Colours also work in the same way as the various shades of grey, so if you can find colours which give intermediate grey responses you may be able to distinguish between a few specific colours.

Try monitoring the voltage output from the sensor while you try different colours in front - obviously it's highly critical that all samples are exactly the same distance away.

kenanizmirli

thank you. i think i will use white grey and black.