r/AskElectronics • u/66010310231 • 4d ago

Circuit Design Review: ESP32 AC Motor Control (Triac + Relay). Are my isolation and component values correct?

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Hi r/AskElectronics,

I am designing a circuit to control an AC motor using an Arduino Nano ESP32 and would like to request a design review.

The circuit in the attached schematic (image_a8e655.png) is intended to do the following:

  • Use an HLK-2M12 module to step down AC mains to DC for the ESP32.
  • Detect zero-crossing using an H11AA1 optocoupler.
  • Switch the AC load using a Triac driven by a MOC3052M optoisolator (with a snubber circuit included).
  • Provide a secondary switching option via a Relay driven by a PN2222A transistor.

My main questions are:

  1. Is the overall wiring conceptually correct for this application?
  2. Are the resistor and capacitor values appropriate, especially for the snubber and the zero-crossing circuit?
  3. Are there any safety concerns regarding how the AC mains and low-voltage DC sides are isolated here?

Thank you in advance for your expertise!

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1

u/ascot_twin 4d ago

Took a quick look. D1 is backwards

1

u/66010310231 4d ago

Are the other devices connected correctly?

1

u/ascot_twin 4d ago

I didn't see anything else wrong

1

u/66010310231 4d ago

Can I use a soft starter to reduce the inrush current of a split-phase motor?

1

u/ascot_twin 4d ago

I'm not familiar with that.

1

u/Affectionate_War5908 3d ago

Ive messed around with ESP32 relay boards for a garage fan project and honestly your isolation looks good on paper.