Light Detector Board 333046 output current and 24VDC operation

TECHNICAL SUPPORT Sensors & Modules
1

Customer:

We need to supply 24VDC to a board and get a 24VDC signal out when it detects light. Could the Light Detector Board (part #333046) be modified to work with 24VDC?

Originally submitted via email support on 22 September 2025. Migrated to the forum for community visibility.

2

Soldered Support:

This board can only work in a 24V network with external modifications. You would need to:

  1. Use a step-down module to convert 24V to 5V for the VCC and GND pins
  2. Level shift the Dout pin from 5V logic to 24V logic
  3. Use a p-channel MOSFET with some resistors to act as a gate, switching the output from 0V to 24V based on the 5V output from the board

The IC doesn’t need anything else external to function.

3

Customer:

Can you send a schematic? Also, looking at the schematic online, it doesn’t show where the photo cell is connected to the comparator. Where is it connected?

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4

Soldered Support:

After further testing, using a MOSFET as a logic gate isn’t straightforward. What you would actually need is a microcontroller and relay to toggle the 24V digital output on and off. While this could be done using our breakout, it would be inconvenient and require programming and additional parts. Our breakout is designed for 5V/3.3V microcontrollers, not for this use case. After testing, we wouldn’t recommend it for your application.

5

Customer:

What is the max load current for the output on the board?

6

Soldered Support:

The maximum output current is about 20mA on the Dout pin, per the LM393 datasheet. The board is really meant for microcontroller-based circuits.

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7

Customer:

Could this output pull in a 5V relay?

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8

Soldered Support:

No, it won’t work. The current just isn’t enough. Testing confirmed the relay clicks when connecting straight to VCC or GND, but the Dout pin on the board can’t trigger it.