Application Notes

CKT-SQUEAL: User-Programmable Sound Player

CKT-SQUEAL: User-Programmable Sound Player
CKT-SQUEAL: User-Programmable Sound Player
Brand: Iowa Scaled Engineering
Product Code: CKT-SQUEAL
Availability: 4 pcs  (What's this?)
Price: $39.00

Available Options

* Speaker:

* Memory Card:

   - OR -   

The CKT-SQUEAL is a cost-effective, user-programmable sound player designed to allow the user to easily embed sound effects in electronic project or model railroad applications.  The module takes standard microSD memory cards, and can be programmed by the user with any standard WAV file.  With four inputs, the device can play four different sets of sounds.  Each sound can be configured to play only once, play a single sound over and over as long as the input is grounded, play random random sounds every time an input is grounded,  or play three sounds in sequence (known as "beginning-middle-end" mode) while repeating the middle sound as long as the input is down.

The CKT-SQUEAL is an effort to balance sound quality with cost, to make adding bits of ambient sound affordable for everyone.  It won't replace your hi-fi system any time soon, but provides 16 bit sound from 45Hz to 16kHz.

Potential applications include crossing bells, flange squeal sounds (when combined with a CKT-IRSENSE while a train is in a curve), church bells, or anything you can think of. 


  • Directly drive speakers with an integrated 725mW audio amplifier and volume control
  • Trigger up to 4 groups of sounds per module
  • Load your own sounds from a microSD card using standard WAV files (up to 48kHz sample rate)
  • Flexible playback configurations:
    • Edge or level triggered
    • One-shot, random, or looping playback
    • Begin-middle-end mode
  • Suitable for many applications including:
    • Flange squeal
    • Grade crossings
    • Wheel "clack-clack"
    • Background effects
    • Ambient Sound

User Guide

User's Manual

Design Files

The latest CKT-SQUEAL hardware design files and source code are now available at GitHub!

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The CKT-SQUEAL is a component intended to be used in a larger system. Suitability for any particular application is the sole responsibility of the end user. The CKT-SQUEAL is made available under license from Michael Petersen and Nathan Holmes. The design is released under the Creative Commons BY-SA license, and the source code is released under the GPL v3.
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