Boeing 737 Start Switch - Servo Operated
This page is split into three main sections:
Parts Guide
Print Guide
Build Guide
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This design is a complete remake of my original Start Switch mechanism; this time, inspired by Mickey’s Flightdeck YouTube video:
https://youtu.be/I7Kqpa-pmkg
The idea of using an MG90S micro‑servo instead of an inductive load such as a solenoid was, in my opinion, absolutely genius. It’s a huge step forward in reliability, simplicity, and performance, and now the only way ahead!
By replacing the weak‑acting, high‑current solenoids, we eliminate the need for reverse‑bias diodes, relays, and separate voltage rails.
The result is a mechanism that is:
Simpler
Stronger
Uses far less current
Runs entirely on +5V
Requires no separate or higher‑voltage power supply
Design Overview
This new version consists of six simple 3D‑printed components, including the knob. All parts are quick to print and straightforward to assemble.
Additional hardware is required; see the Component Parts section for the full list:
https://www.737diysim.com/copy-of-build-guides-1-1/boeing-737-start-switch---servo-operated
Mounting is now more flexible:
You can secure the unit using the imperial nut supplied with most common rotary switches, or
Attach it using the four mounting holes built into the upper case assembly.
A print bed size of 220mm × 220mm is required for the largest part.
Common Question: How do I connect the servo‑operated Start Switch to an Arduino Mega?
Wiring is very simple:
Servo signal → Arduino Mega PWM pin (e.g., D9)
Servo +5V → Arduino 5V (or a separate regulated 5V power supply)
Servo GND → Arduino GND
That’s it—no relays, no diodes, no fuss.
General Information:
