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rpm counter

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mnoman

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i want to make a rpm counter using simple IR LED and detector using the slotted disk and interface it with 89c51 can any one just give me the idea how it may be possible
 
Already discussed in the past

Did you try the search function of this forum? Certainly not because I'm sure you would have find something.

As usual: be more specific!
What is the range of RPM you want to measure, how many slots in the disk, what accuracy do you want, what measuring frequency do you want (1 measurement per hour, or 100 measurements per second?)

Two major possibilities:
1) Measure the time your input is high.
2) Count the number of pulses from a high frequency signal (eg. 4MHz) while your input is high.

Which method to use depends on your requirements.
 
mcs51mc said:
Two major possibilities:
1) Measure the time your input is high.
2) Count the number of pulses from a high frequency signal (eg. 4MHz) while your input is high.

Which method to use depends on your requirements.

Both of the above suggested methods is essentially the same, in fact the second statement is one possible way how one achieves the first.

Another method of rpm measurement is to count the number of incoming pulses in a fixed time interval.

As mcs51mc has already stated, which method works best depends on your requirements.
 
eblc1388 said:
Another method of rpm measurement is to count the number of incoming pulses in a fixed time interval.
Absolutely, that's what I ment but there was a glitch between my brain (if I have 1) and my fingers (I'm sure I have 10 of them) at that time.
 
mcs51mc said:
Absolutely, that's what I ment but there was a glitch between my brain (if I have 1) and my fingers (I'm sure I have 10 of them) at that time.

Can't comment on the brain?, but you should have 8 fingers and 2 thumbs? :p
 
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