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LM324 - IR Sensor

I built the circuit below with the IR sensor on the bread board

A large bowl of snow was brought inside the house to the sense the snow

Varied the 50 K pot (20 turns on the pot)

No buzz output from sensor

Any suggestions on what is going wrong?

Thanks

---+-------+----------+----------- +5 --------VoutLM785 (NTE equivalent one) (Vin) +9V- --------- |

| | | |
|
| | 100K |
|
| | | |
|
| | +-----[22K]-------+ |
|
50K pot | | 1/4 | |
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| |\\| | |\\ 324 | |
|
ref(A)+-----|+\\ +------|+\\ | |
|
IR in | | >--. | | >-----+-+--|| |
|
-------|-----|-/ `-| | |/| 1N914 | | |/ | +| |
|
| | 100K +----[100K]-' | |
|
| 1/4| | | | |
|
100K 324| | === 0.2uF (B) | |
|
| | | | | |
|

-----+-------+----------+---+----------------+--------------------------------------------- GND

Reply to
Manimozhi Baskaran
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-----+-------+----------+---+----------------+---------------------------------------------

I tried to clean up your diagram, which was not clear, and came up with this: ------ ---+-----+----------+--------- +5 ------Vout|LM7805|Vin--- +9V | | | ------ | | | | | | 100K | | | | | | | +-----[22K]-----+ | pot 50K | | 1/4 | | | |\\| | |\\ 324 | piezo | ref(A)+---|+\\ +------|+\\ | 5V-9V | IR in | | >--. | | >-----+-+--|| | -------|---|-/ `-|

Reply to
ehsjr

(Vin) +9V- --------- |

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-----+-------+----------+---+----------------+--------------------------------------------- GND

--
With the 50k pot cranked to zero ohms the reference input to the
opamp will be 5V, and since:

            E1R2
     E2 = ------- ,
           R1+R2

with the pot cranked to 50k the reference input will be:


            E1R2      5V * 100kR
     E2 = ------- = -------------- = 3.33V,
           R1+R2     50kR * 100kR

So there\'s no way you can get to 0.8V, no matter how much you crank
the pot.

What you need to do is change this:

      +----------+----+5V   
      |          |
    [50k]--[--|---------|-/
      |          |
    [100k]       |
      |          |
      +----------+----GND


to this:


      +----------+---+5V
      |          |
    [100k]       |
      |          |
      +---------|+\\
      |         |  >--[--|---------|-/
      |          |
    [50k]------+--[--|---------|-/
      |          |
    [50k]
Reply to
John Fields

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