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Circuit to detect direction of wheel rotation

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skummamuru

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Hi

I was wondering if anyone could help me figure this one out....

A circular wheel is half painted black and the other half painted white. There are 2 censors mounted 45 degree apart at the surface of this wheel( not touching the wheel) which give a "1" for black and "0" for white passing under them. Design a circuit to detect which way the wheel is moving. Can not assume any fixed position for start.

Thanks ...
 

This is simple.
It is like this:
You measure how much time needs that a sensor gets from 1 to 0, and depending on that to see in which dirrection is moving.
 

This SOUNDS LIKE A HOMEWORK assigment .Please don't cheat .. And try to solve the problem by yourself.This are HARD TIMES employers expect good trained people .You will only harm yourself .. If all what i said don't match your profile.. Well forget it then ,,But i think that the advice will still hold true for somebody else.
 

Could be a first offence, so let's go easy on him.

Here's a small hint: "quadrature encoder".
Now go learn about them!
 

I am trying to design something simmiliar. I am trying to decode quadrature switch that outputs 2 series of pulses with phases shifted 90 deg. Depending on direction of rotation the shift is either 90 deg or -90 deg.
It seems that D flip-flop would do the job to decode the direction but I was not able to get it working.
the output should be logic 1 in one direction and logic 0 in the other.
one of the switch outputs is connected to D input, the other is connected to Clock.
At some point of turning the flip flop goes to low.
any ideas?
 

You can search this forum for "rotary encoder" or "motor speed control".

To sanasar:
Make sure your pulses have 50% ratio..oterwise D Flip-Flop will not work correctly.
You may need first to devide both square waves by 2 and then D will cope with direction without problems..
 

Here is a document. Where u will get a lot of such interresting questions & ans. The answer of your question is aviliable on page no - 33.
 
Here are some more ....
i have collected these from different places & merged them
 
wat r the various way to implement ab + c using 2 transistors? ..
any guesses?
 

HI ,


i have also that question before , but not for that application , for wheel mouses !

and at last got the result ,

when the wheel has not started rotation , 4 differents conditions could occur on outputs of sensors ,

sensor1 ( s1 ) is 0 ( white ) , sensor2 ( s2 ) is 0 (white )
or :
s1 = 0 , s2 = 1
or
s1 = 1 , s2 = 1
or
s1 = 1 , s2 = 0

NOTE : you should know where each sensor is located , i mean if s1 is in left of s2 or right of s2 ?

we imagine s1 is located in left of s2 :
so :
in first condition : ( S1=0 ,S2=0 )
if after rotation , FIRSTLY S1 goes 1 , then it is rotating from left to right ,
if after rotation , FIRSTLY S2 goes 1 , then it is rotating from right to left ,

and so on .... ,

now you can findd the way !
scan two sensors on high speed , wait in this loop until both sensors are on same color , black or withe ( 0 or 1 ) , then verify which sensor changes it's condition sooner than other , ( changing from 1 to 0 OR 0 to 1 )
then you can say the rotation of the wheel is from side of this sensor to another sensor .

i hope i could describe well ,

Regards.
 

A simple implementation of this using only a single D flip-flop.
think simple, .


**broken link removed**
 

boneymat..u can implement it using 2 nmos with one nmos having A connected to drain and B connected to gate and source connected to the source of the other nmos and that nmos has its gate connected to vdd and its drain connected to C

Added after 1 minutes:

sorry forgot to mention that u need to take the output from the common source of both..this may not work very well as there will be Vth drop..but well there are better methods
 

it seems difficult in big company interview,do anybody tell me how to get more basic knowledge as soon as possible.

thank you!
 

There is no course or book available like "Learn VLSI basics in 24 hrs"...... It has to come from the beginning.

When you do your schooling or engineering, you have to be serious enough to study properly without wasting time.... Now even if you manage to learn some good stuff in just 2 to 3 weeks, it wont last long.... Seriousness is important in studying. This is what the BIG companies expect.

https://hdlplanet.tripod.com/
https://groups.yahoo.com/group/hdlplanet
 

can anybody share VHDL mostly asked questions in interviews
 

I am looking for asic engineer interview questions:?:
 

eltonjohn said:
This SOUNDS LIKE A HOMEWORK assigment .Please don't cheat .. And try to solve the problem by yourself.This are HARD TIMES employers expect good trained people .You will only harm yourself .. If all what i said don't match your profile.. Well forget it then ,,But i think that the advice will still hold true for somebody else.
Click to expand...

One of the good qway to learn is asking. You sound like a hypocrite
 

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