circuit reqiured for simple project?

Question

OBJECTIVE:
1)circiut to count number of black strips(on a white back ground)
# numbering can be in binary ie (range of 0-15) with 4 LEDs each reprsenting 0-1
2)circuit to give a signal (lighting of LED) if RED colour strips are countered (on a white back ground)

NOTE:
1)must differntiaite between red ,black,white.
2)lighting ,exact intensity of red is not known so the Answerer should explain the logic clearly so that adjustments might be possible.
3)exact specifications of electronics used will be added advantage
4)circuit diagram should be mailed to [e-mail]
5)the answer if elaborate will be greatly appreciated since the user is a novice

Answer 1

Are you asking for the entire circuit diagram to complete the project? Why do a project like this if you are not going to learn how to do it?

I can do the diagram; I am just curious why you would bother. If you like I can tell you how, and what to look at, so that you can figure the design out yourself,


I can say look up 74LS163 which is a 5V TTL logic chip that counts to Binary 15, and its outputs can be directly used to run small 2mA LEDs, use a photo detector and an led pointing at the same position, that would move along the wall. The photo detector used in the reverse bias direction can be used to detect the light intensity reflected off the wall. As more light reflects (while over white wall) the photodiode will flow most freely giving you a lower voltage drop, when the wall is black, the voltage drop across the photo detector will increase to the highest voltage drop across the photo detector. For red you will need to observe the particular voltage drop, it will also depend on what color LED you are using to shine onto the wall. Once you have observed what the voltage drops will be for each color, you can use comparators, a LM339 will provide 4 comparators (quad comparator IC) you set the comparator to detect when the voltage drop passes a particular voltage for each color, the output of a comparator is either High or Low, depending on what you use as the input , and what is the comparison voltage(usually picked with a simple resistor bias) the LED, Photo detector, and comparators used correctly will provide a simple set of logic outputs, from which you can make a decoder using TTL gates, look up AND, OR, NAND, Inverter gates all with Chip numbers like 74LS00, 74LS04, 74LS08, etc the decoder you make will tell the inputs on the 74LD163 (binary counter IC) when to increment, reset, load a 4 bit inputs, etc. hope this helps, I can tell you also that you will be able to run the entire circuit of a 5V power source as long as you stick to the 74LS series TTL logic devices. The comparators and LEDs and photo detectors all can run at 5V or less. Learning these chips is quite stimulating when you finish and a bunch of little chips put together the right way completes your task as you desire, you can ask me specific questions if you wish, although I'm not fond of just telling someone what to do, I'd prefer someone take initiative and just ask for suggestion, direction, where to look kinds of help.

good luck
-John

Answer 2

This request is well beyond the scope of this forum!
You are asking a whole machine design...
Thinking that you can solve it with a few gate won't work: you will need some processing power, even just to distinguish the levels of the colours!
You also have a problem of optics and filter...
Are you trying to read bar codes?
Or to measure the Density of the colour?
I suggest you search the web for "machine vision" or books on that subject.