Pulse to the ic

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legend killer

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Hi everyone,
i m trying to make a counter with an infrared sensor.the counter should count the number of times the infrared beam is cut.
I have the 74160 ic for counting.i made the infrared sensor which gives output of 3.4 v when the beam is cut
i m stuck with the pulse input to the 74160 ic.i m not getting proper results when i m connecting the output of opamp(which i m using as a comparator)
can anyone tell me how to give pulse to the ic in this ay
 

hi,
Post your circuit diagram so that we can see how you have the 74160 etc, connected.
 
hi,i've attached a word document with necessary details
any help is greatly appreciated.thanks
 

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hi,
Looked at your circuit.
Can you measure with a voltmeter the voltages at the clock pin of the LS160, when the IR detector LED is illuminated by IR and also when its not.
That will give an indication of the voltage range coming from the LM358 output.

Are you using a standard RED LED as the IR detector.???
 
I m not using red led but standard ir sensor.when ir is illuminated, voltage at clock input is 0.69-0.7 v.when the beam is cut ,voltage is 3.5 volts.i also kept ce,reset,preset,carry in inputs at logic 1
 
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I connected everything as hayato told me.the problem i m facin is this-i know that ic is+ve edge triggered .so when the ir beam is cut,the voltage level rises and the output should change states.but when i made the ir led incident once again, then also output is changing,that is during negative edge.the ic is working properly as i checked with ic tester
 
hi,
The most likely cause of false clocking is that the LM358 has no hysteresis and will oscillate at switch over.

Try adding the two feedback resistors shown in the drawing, they will give some hysteresis for positive feedback.

If required change the 220K to a value of 100K thru 1Meg ohm to give the best result.
 

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Agreed. Open loop is not your friend. =D
 
Hey,i tried the ckt which u gave me,but not gettin the desired result.will it help if i connect the buffer btwn the output of opamp and input of clk pin
 
I think the LM358 is so slow that it produces a slow ramp instead of an "edge".
Use a much faster LM393 diual comparator IC instead and it needs a pullup resistor at its output.
 
Can u plz explain in some detail so that i can know what to do.i dont have much knowledge about that as i m a newby.any help is greatly appreciated
 
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