38 kHz IR Proximity Sensor

Having trouble getting the proper output on from the device. wired up as per the schematic,
Pin 4(with square copper trace) is GND…
pin 1 - tied low to pin 4
pin 2 - output to resistor/LED ckt(test purposes)
pin 3 - +5V
pin 4 - GND

Connected as above the output is ~5V and LED is on. Any motion or movement in front of the sensor does nothing. The LED remains on. Removing pin 1(Enable) from ground causes both the reg and green LEDs on the device to light up. Output LED is off and remains off even with motion.

What gives?


Are you using the Low Brightness or High Brightness version of our 38 kHz IR Proximity Sensor?

It sounds like you are refferring to the ENABLE pin as pin 1. Please note, as mentioned on the product pages, the ENABLE pin turns off the IR emitter LED when it is set low, so tying it to ground will essentially disable the sensor.

The OUTPUT pin is high by default (e.g. when nothing is being detected) and remains low as long as the receiver is detecting the reflected IR light. When the OUTPUT pin is low, the red LED on the board will be on to indicate something is being detected. Please note that these sensors can be fairly sensitive, so you should make sure that there is nothing in the potential field of view when testing them.

If you still have problems getting the sensor to respond, could you post pictures of your setup that show all of your connections, and clearly show the area around the sensor?


Thanks for your response.
The low output is exactly what I need to trigger a 555 timer circuit to activate a light for 10sec. I may have been a bit confused about the enable pin configuration, but I did test it with it tied to ground and unconnected with no results. I will go back again and try this again.
I will post specifics if I continue to have trouble.

Nope. I’m not having any luck.
Left to right (GND, Vdd, Out, En)
Source = 5V
reference to GND
5V on Vdd
0V on Out
5V on En
Enable with no connection
As soon as power is applied, both Green and Red LED’s on the PCB are on and remain on until power is removed.

Just found out the most probable cause of my troubles. It was a couple of jumper wires that were too close to the sensor that caused it to say on all the time. It is working now.

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I am glad you were able to get it working! Thank you for letting us know what the problem was.

Good luck with your project!