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A circuit was setup to detect obstacle (proximity sensor) using IR transmitter which uses Arduino to generate 40 kHz Frequency (the frequency was checked using a digital oscilloscope and it displays 40 kHz) and TSMP58000 as IR receiver, but the voltage at the output of the IR receiver when an IR pulse gets detected is seen as 3V instead of a value ~0V .What could be the issue?

Receiver used - http://www.vishay.com/docs/82485/tsmp58000.pdf (it receives in 20 kHz - 40 kHz range)

The screen shot of the transmitter and receiver circuits are as below where 4th terminal of IR transmitter is connected to the arduino pin and IR led is connected to the ground. External Power supply is used to power the IR receiver and common ground is used for both.

enter image description here

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  • \$\begingroup\$ If you are seeing 3V then surely this is the receiver detecting a signal whereas 0V is no detect? Oh it's an open collector output. What signal do you see when nothing is detected? \$\endgroup\$ – Andy aka Sep 24 '15 at 11:58
  • \$\begingroup\$ I can see a signal of 5V when nothing is being detected. \$\endgroup\$ – Preethi Sep 25 '15 at 11:45
  • \$\begingroup\$ What is connected to the output and what are you measuring the signal with? \$\endgroup\$ – Andy aka Sep 25 '15 at 11:53
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This is a open collector output, if you see Figure 1 of the datasheet : Fig 1 in the output is inversed compared to the input with a delay time.

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You are seeing the carrier. The detector outputs the carrier so when measured with a voltmeter you get the mean value. Try hooking it up to a scope or start counting the pulses with the Arduino.

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