LDR sensor module with LM393 as darkness switch for LED control

TECHNICAL SUPPORT Sensors & Modules
1

Customer:

How can I adapt the LDR sensor module with LM393 to use it as a darkness switch that turns on a light automatically at night? Would it work with just a 10k resistor or a MOSFET, without using an Arduino? What are the two empty holes near the LDR resistor used for?

Originally submitted via email support on 23 April 2019. Migrated to the forum for community visibility.

2

Soldered Support:

To use this sensor as a darkness switch without Arduino is straightforward. To suggest the best circuit, please tell me: will you be using a DC or AC light?

3

Customer:

I want to integrate your LDR board into a solar bulb I bought. The bulb has a small board with just an on/off button, a 5V input for the solar panel or charger, and a 3.7V Li-ion battery. Currently the lamp is always on. I need to add elements to your board so it only works at night. Can I connect your board between the mini board’s on/off button circuit and the lamp? How would I do that?

Attachment omitted in migration: ICOCO-15-w-L-mpada-LED-de-Alta-Qualidade-Port-til-de-Energia-Solar-Painel-Solar.jpg_640x640.jpg

Attachment omitted in migration: IMG_20190424_135425.jpg

4

Soldered Support:

To make this work, you need to connect an N-channel MOSFET to amplify the signal. Wire it as follows:

  • Gate: connected to the DO pin of the LM393 board
  • Drain: connected to the negative (-) of the LEDs
  • Source: connected to the GND pin of the LM393 board

Use the potentiometer to adjust the sensitivity of the sensor.

5

Customer:

Where do I connect the negative and positive wires from the battery?

6

Soldered Support:

The red wire is positive (+) and the black wire is negative (-) from the battery.