The diagram below provides a visual reference for wiring of the components. This diagram was created using the software package Fritzing.

Adafruit Library for Fritzing

Use Adafruit's Fritzing parts library to create circuit diagrams for your projects. Download the library or just grab individual parts. Get the library and parts from GitHub - Adafruit Fritzing Parts.

Wired Connections

Feather M4 Express

  • D5 from Feather to Pin #5 on ULN2803A
  • D6 from Feather to Pin #6 on ULN2803A
  • D9 from Feather to Pin #7 on ULN2803A
  • D10 from Feather to Pin #8 on ULN2803A
  • 3V from Feather to VCC (upper) rails on Perma-Proto
  • GND from Feather to Ground (upper) rails on Perma-Proto 


  • EN from Feather to Switch
  • GND from Feather to Switch

DC Jack

  • Ground to Ground (lower) rails on Perma-Proto
  • VCC to VCC (lower) rails on Perma-Proto


  • Pin #10 (VCC) from ULN2803A to VCC (lower) on Perma-Proto  
  • Pin #9 (GND) from ULN2803A to GND (lower) rails on Perma-Proto



The Adafruit board can be powered via USB or JST using a 3.7v lipo battery. In this project, a 400mAh lipo battery is used. The lipo battery is rechargeable via the USB port on the board. The switch is wired to the enable and ground pins on the board.

12V Power

The 12V 5A power supply is plugged into the DC jack on the lower power and ground rails on the Perma-Proto. 

The power and ground rails connected to the 12V 5A power supply must only be used to power the solenoids NOT the Feather!

This guide was first published on Aug 05, 2020. It was last updated on May 19, 2024.

This page (Circuit Diagram) was last updated on Mar 08, 2024.

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