Hello hope you can help me finish my logic circuit. I'm trying to make a circuit that counts people and when it reached 19 it will alarm. I'm using counter IC 4026, Xor gate, ir sensor module and a bcd 7 segment display. The sensor seems to be working but the counter does not change the display its only 0. I just followed some yt video in making this. ANd I'm planning to add a buzzer that will alarm when the counter reached 10.

Mod: lightened your image.E

 

Hi gelzky,
Welcome to AAC.
Do you have a circuit diagram you could post.?
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Hi gelzky,
Welcome to AAC.
Do you have a circuit diagram you could post.?
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here it is

 

hi ,
I do not see any VDD power to pin 16 of the 4026.??

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Do you have a PULL DOWN resistor on RESET?
Does your optical sensor need a PULL UP resistor to Vcc? Many of them have open-collector outputs.

 

hi ,
I do not see any VCC power to pin 16 of the 4026.??

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oh yes, i connected it already just forgot to note it. but still circuit doesn't work

 

Do you have a PULL DOWN resistor on RESET?
Does your optical sensor need a PULL UP resistor to Vcc? Many of them have open-collector outputs.

yes, I just added it tho the counter still does not work. what do you mean by open-collector outputs.

 

what do you mean by open-collector outputs.

Like this logic gate
https://www.ti.com/lit/ds/symlink/s...12975&ref_url=https%3A%2F%2Fwww.google.com%2F
There is a diagram of the internal circuitry on page 8. Without a resistor between OUTPUT Y and VCC it cannot give a 5V output. The output would always be logic zero.

 

hi g,
OK,
It looks OK, compare it to this diagram.
Have you checked the signal is actually coming out of the sensor.?
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Don't get distracted regarding open collector outputs.

 

Like this logic gate
https://www.ti.com/lit/ds/symlink/sn7407.pdf?ts=1638803612975&ref_url=https%3A%2F%2Fwww.google.com%2F
There is a diagram of the internal circuitry on page 8. Without a resistor between OUTPUT Y and VCC it cannot give a 5V output. The output would always be logic zero.

so which output and vcc it is?

 

hi g,
OK,
It looks OK, compare it to this diagram.
Have you checked the signal is actually coming out of the sensor.?
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Don't get distracted regarding open collector outputs.

yes the sensor lights up including the led when i pass something through it. I don't know what really the problem is

 

hi g,
Ok,
Look at the circuit I posted, add the Clock push button, then try clocking the 4026 that way to prove that part of the circuit, [ disconnect the sensor]
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so which output and vcc it is?

Figure 3

 

hi g,
Ok,
Look at the circuit I posted, add the Clock push button, then try clocking the 4026 that way to prove that part of the circuit, [ disconnect the sensor]
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it just started blinking :< please help:<

 

hi g,
Are you saying it is counting with push buttons.?
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Edit: is the 4026 circuit wired as the circuit I posted.?


Pin #5 should not be grounded it is the carry out pin.

 

no it

hi g,
Are you saying it is counting with push buttons.?
E
Edit: is the 4026 circuit wired as the circuit I posted.?


Pin #5 should not be grounded it is the carry out pin.

View attachment 254423

no, it is not counting :< where does pin 5 should be connected?

 

hi,
Pin #5 would go to the next 4026 Clock input if you were using two 7 segment display to count to 99.

If that simple circuit using two push buttons does not work, Clock and Reset then check your wiring and 4026 IC.

Those push buttons can easily be connected the wrong way around, make sure when they are pressed that pins #1 Clock goes High, use a voltmeter to measure pin #1. Do the same for pin #15 Reset.

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Check this video.
https://components101.com/ics/ic-cd4026-pinout-circuit-datasheet

 

hi,
Pin #5 would go to the next 4026 Clock input if you were using two 7 segment display to count to 99.

If that simple circuit using two push buttons does not work, Clock and Reset then check your wiring and 4026 IC.

Those push buttons can easily be connected the wrong way around, make sure when they are pressed that pins #1 Clock goes High, use a voltmeter to measure pin #1. Do the same for pin #15 Reset.

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Check this video.
https://components101.com/ics/ic-cd4026-pinout-circuit-datasheet

that worked!:>>> tysm! i tried to check the push buttons' output using led then it fixes it now the 7 segment counts. tho I tried to connect the sensor back but it does not count again? help me pls :>>>

 

hi g,
That's great, at least you know the 4026/LED is now working.

Try this, connect the sensor to the input pin #1 of the 4026, measure with a voltmeter the voltage on pin #1 while you move your hand about in front of the sensor, what voltage do you measure.?

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hi g,
Now try this change to your sensor to 4026 pin #1,
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