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I am assembling a proximity IR Sensor using TSOP instead of a photodiode. I followed the diagram below. When I tested the circuit, and put my hand close to the IR LED, the receiver receives the signal in just one second, from 0.7 V to 5 V instantly.

How can I make a low output constantly if my hand is close to the IR LED? Please tell me what is wrong. I am using a TSOP VS1838b as the receiver and an IR LED using a 555 IC transmitter operating at 38 kHz.

Transmitter

Receiver

Reference article

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  • \$\begingroup\$ Does this answer your question? Vs1838B break beam problem So basically, the IR receiver does not work with continuous 38kHz "tone". \$\endgroup\$
    – Justme
    Aug 16, 2020 at 17:53
  • \$\begingroup\$ Is there a way I could achieve it without any programming? Also is there a specific receiver that works in continuous 38kHz? \$\endgroup\$ Aug 16, 2020 at 23:37
  • \$\begingroup\$ It is possible to put another 555 set to 600us on 600us off square wave to control the 38kHz 555. And a receiver that works with continuous 38kHz might exist, but it might not be called infrared remote receiver. \$\endgroup\$
    – Justme
    Aug 17, 2020 at 4:12
  • \$\begingroup\$ Okay thank you for your answer. How about I will replace the tsop 1838 to 1738 does that make any difference? \$\endgroup\$ Aug 17, 2020 at 8:10
  • \$\begingroup\$ The datasheet does not mention it but most likely it won't work. You are trying to use an infrared remote receiver as proximity sensor, and they are good for receiving infrared remote signals. Simply get an infrared proximity sensor which is meant for the job. \$\endgroup\$
    – Justme
    Aug 17, 2020 at 9:00

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The problem is your TSOP1838 IR receiver. It has AGC and cannot receive the "continuous IR signal" from your simple 555 oscillator. You need a fixed-gain IR receiver such as a TSOP4038 or TSSP4038, which has fixed gain to solve your problem. FYI you can buy premade modules to do precisely this, such as https://www.aliexpress.us/item/2251832789524926.html or search for KY-032 4pin IR Infrared Obstacle Avoidance Sensor Module

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