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Help needed with Frequency Counter

malsch

Apr 29, 2011
4
Joined
Apr 29, 2011
Messages
4
Hi, I need to design a simple frequency counter to measure the frequency of a square wave input (hence signal conditioning is not needed for now). I have understood the concept that the counter needs to count the input pulses for 1 second and display them on a 7-segment. My problem is how am i going to use the latch function (LE) to keep showing the frequency that was counted.

This is what I came up with so far:


The input signal (in this case 50Hz) triggers the 1Hz monostable, hence counts for 1 second. The problem is that after that 1 second, the counter resets to zero and recounts to 49 in this case. I need to find a way to keep the counter on 49 rather than going back to zero. Later I will add a 10Hz and 100Hz monostable for decimal points but for now I need to understand this concept.

Thank you.
 

Kabelsalat

Jul 5, 2011
176
Joined
Jul 5, 2011
Messages
176
You should have a set of latches between the 74HC192 counters and the 74HC4511 decoders.

Also using a 555 to get excactly one second is quite hard. For the counter to be correct you must be able to get a pulse that last for excactly one second.
 
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