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CD4033 higher input frequency variant?

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neazoi

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Hi, I want to build a MCU-free frequency counter and I have found this circuit (attached). Several of these can be cascaded for measuring higher frequencies.

However it's max input frequency is something like 10MHz or so, at 12v.

I am looking for another variant that can do up to 30MHz.
Can you please suggest one?
 

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  • frecount.PNG
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Sorry, but what you've got there, contrary to the title, is NOT a frequency counter. It's just a counter. I would suggest you just use a small cpld to do what you want.
 
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    neazoi

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Connecting a LED display without current limiting resistors at 9V supply will typically exceed the CD4033 absolute maximum ratings and potentially fry the IC. Apparently a copy-and-paste error when picking up the original circuit from https://www.homemade-circuits.com

Clock speed limit is imposed by basic properties of the 4xxx high voltage logic. There's no fast logic family with >5V supply.
 
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    neazoi

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For a frequency counter, requires an accurate timing gate, which will allow the pulses to be counted within a preset time. The original circuit as drawn, as shown IS NOT a frequency counter, but a simple pulse counter.

But to your question....have you checked whether the CD4033 is available in the 74HC40xx series?

Those circuits are anywhere from 10 to 20 times faster than the CD40xx series.
 
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    neazoi

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The CD4033 only has standard CMOS outputs, it isn't intended to drive LEDs even with current limiting resistors in each segment. The data sheet shows suggested driver circuits if LEDs or some other types of display are used.

I concur, the circuit is only a counter, it can't tell you the frequency of input pulses, only how many of them there are.

Brian.
 
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    neazoi

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