Engineer’s Notebook #1


This is the inaugural issue of the Engineer’s Notebook from Iowa Scaled Engineering. We hope to make this a semi-regular thing, not only talking about our products and what we’re working on, but also including some other features in the future that we believe will be relevant and interesting. Let us know your thoughts, including what topics might be of interest to you.

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Squealer Update

Testing of the Squealer – a motion activated flange squeal module – is progressing well and we would like to thank all those who have participated in the initial testing. As we get closer to the official product launch at the St. Louis RPM, July 28-29, 2023, we would like to share some more details.

The basic Squealer kit consists of a motion sensor, the control board, and a separate speaker that can be positioned for the best sound quality.

About the same size as our popular TrainSpotter IR detectors, the motion sensor provides a discreet way to sense actual motion of your trains – an industry first, as far as we know. The control board contains the brains of the system, built-in flange squeal sound effects, connection points for the motion sensor, an audio amplifier, and a microSD card slot. Power comes from 5V to 24V DC or through the USB jack using a USB phone charger and Mini USB cable. We are also investigating the possibility of powering it directly from the DCC bus. The speaker is the same size as our popular SoundBytes sound modules – a hair over 1 inch cubed. In other words, just provide a power source and everything else needed to add flange squeal to your layout is included.

While the Squealer works out of the box in most situations, using sounds professionally recorded and edited by Scale Sound Systems, users can also customize their experience by loading sounds onto a microSD card. This opens the possibility of a wide range of motion triggered sounds – ranging from flange squeals, to creaks and pops, to yard sounds and more – only your imagination is the limit!

In addition to the single Squealer kit, we also plan to offer a discounted 3-pack for users with many curves or for creating that all-encompassing stereo effect on one special curve.

For more details on the installation of the Squealer and its capabilities, take a look at a preview of the instruction sheet here.

Stay tuned for more updates in the coming weeks, including pricing, as we solidify those details.


  1. This looks fantastic! Would it be possible to attached two motion sensors and mount them say at both ends of a curve so you’d get the sounds throughout the entire length of the curve in either direction?

    1. Yes. You can connect as many sensors as you want to a single Squealer. Alternatively, multiple Squealers spaced around the curve provides some nice layering of the sounds.

  2. Looking forward to picking one up in St. Louis if I’m lucky enough to get there before they are sold out! I think I might actually use it as a defect detector (of sorts). I’d also be interested in powering it from the DCC bus if you guys figure out that solution.

  3. Great! Will you be offering the motion sensors for sale individually for this purpose? Layered sounds from multiple Squealers would be very cool, but the multiple sensor option is nice as well.

    1. The sound currently is only motion dependent and not sensitive to speed.

      The current sounds were recorded from a small shortline and are perfect for yards and low-to-mid speed operation. There’s about 19 different clips in there, and they’re played randomly and with varying delays so that to the ear, you should not notice any repetition like you’d get with a single record. We are planning to record high speed, welded rail mainline squealing as an option at some point, but that’s down the road a bit when one of us gets time to take some microphones down to a nice quiet place on the Transcon.

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