How to count pulses per second ?
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Posted by Mike C on February 13, 2007, 5:05 pm
Please log in for more thread options Hi, I'm hoping someone could help me create a very basic circuit which would: Count the number of pulses it receives per second (from a 555 timer, or a switch, for example) and if the number of pulses per second is equal to, or greater than 10 it turns on a transistor. So basically it should check every second if a clock frequency of 10Hz is being met - if so, a transistor should turn an LED on and keep it on for as long as 10Hz a second is hitting the circuit. As soon as the clock stops, or the frequency goes below 10Hz, it should turn off the LED. Thanks so much for your help ! MC | |||||||||||||||||||||||||
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Posted by D from BC on February 13, 2007, 5:13 pm
Please log in for more thread options Maybe give the LM2907 Frequency to Voltage IC a boo??? D from BC | |||||||||||||||||||||||||
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Posted by Tim Williams on February 13, 2007, 5:41 pm
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If it's constant, missing pulse detector. Can be made from a few transistors, or a few transistors and a comparator, or a single chip (LMxxx?) that does it. Hell, it can be done with the 555, IIRC. If it's not constant, then a decade divider like CD4017 set to reset every second (so you need another clock) and something to say that it's got enough counts or it doesn't. Tim -- Deep Fryer: A very philosophical monk. Website @ http://webpages.charter.net/dawill/tmoranwms > Hi, I'm hoping someone could help me create a very basic circuit which
> would: > > Count the number of pulses it receives per second (from a 555 timer, > or a switch, for example) and if the number of pulses per second is > equal to, or greater than 10 it turns on a transistor. > > So basically it should check every second if a clock frequency of 10Hz > is being met - if so, a transistor should turn an LED on and keep it > on for as long as 10Hz a second is hitting the circuit. As soon as the > clock stops, or the frequency goes below 10Hz, it should turn off the > LED. > > Thanks so much for your help ! > > MC > | |||||||||||||||||||||||||
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Posted by Mike C on February 13, 2007, 5:58 pm
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> If it's constant, missing pulse detector. Can be made from a few
> transistors, or a few transistors and a comparator, or a single chip > (LMxxx?) that does it. Hell, it can be done with the 555, IIRC. > > If it's not constant, then a decade divider like CD4017 set to reset every > second (so you need another clock) and something to say that it's got enough > counts or it doesn't. > > Tim > > -- > Deep Fryer: A very philosophical monk. > Website @http://webpages.charter.net/dawill/tmoranwms > > > > > Hi, I'm hoping someone could help me create a very basic circuit which
> > would: >
> > Count the number of pulses it receives per second (from a 555 timer,
> > or a switch, for example) and if the number of pulses per second is > > equal to, or greater than 10 it turns on a transistor. >
> > So basically it should check every second if a clock frequency of 10Hz
> > is being met - if so, a transistor should turn an LED on and keep it > > on for as long as 10Hz a second is hitting the circuit. As soon as the > > clock stops, or the frequency goes below 10Hz, it should turn off the > > LED. >
> > Thanks so much for your help !
>
> > MC
Guys, thanks alot for your response. In this case, the clock frequency is variable, so it would just need to count the number of cycles per second, and a missing pulse detector may not do it. I can see how a decade divider could work (I just dont have any lying around now, and would like to build it this week). What did you have in mind by doing it w/ just transistors and a 555 ... or a comparator .. im looking for anything crude and simple. :) Thanks again ! MC | |||||||||||||||||||||||||
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Posted by Rich Grise on February 13, 2007, 6:58 pm
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On Tue, 13 Feb 2007 14:58:15 -0800, Mike C wrote: >> If it's constant, missing pulse detector. Can be made from a few
>> transistors, or a few transistors and a comparator, or a single chip >> (LMxxx?) that does it. Hell, it can be done with the 555, IIRC. >> >> If it's not constant, then a decade divider like CD4017 set to reset every >> second (so you need another clock) and something to say that it's got enough >> counts or it doesn't. >> >> >> > Hi, I'm hoping someone could help me create a very basic circuit which
>> > would: >>
>> > Count the number of pulses it receives per second (from a 555 timer,
>> > or a switch, for example) and if the number of pulses per second is >> > equal to, or greater than 10 it turns on a transistor. >>
>> > So basically it should check every second if a clock frequency of 10Hz
>> > is being met - if so, a transistor should turn an LED on and keep it >> > on for as long as 10Hz a second is hitting the circuit. As soon as the >> > clock stops, or the frequency goes below 10Hz, it should turn off the >> > LED. >>
>> > Thanks so much for your help !
>
> Guys, thanks alot for your response. In this case, the clock > frequency is variable, so it would just need to count the number of > cycles per second, and a missing pulse detector may not do it. I can > see how a decade divider could work (I just dont have any lying around > now, and would like to build it this week). What did you have in mind > by doing it w/ just transistors and a 555 ... or a comparator .. im > looking for anything crude and simple. :) > The dead simplest would be an RC low-pass or high-pass, and a comparator. You'll have hysteresis, if you don't want your comparator oscillating, and it won't respond very quickly, but it'll demonstrate the concept. Good Luck! Rich | |||||||||||||||||||||||||
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>would:
>
>Count the number of pulses it receives per second (from a 555 timer,
>or a switch, for example) and if the number of pulses per second is
>equal to, or greater than 10 it turns on a transistor.
>
>So basically it should check every second if a clock frequency of 10Hz
>is being met - if so, a transistor should turn an LED on and keep it
>on for as long as 10Hz a second is hitting the circuit. As soon as the
>clock stops, or the frequency goes below 10Hz, it should turn off the
>LED.
>
>Thanks so much for your help !
>
>MC