The Rusty Spike

A Railroad Fan's Website


Completion: 1:24 Model of a Whelen Liberty Lightbar

And that’s a wrap. Well, almost. I need to bump up the amplification on the headlights and decal the model, but other than that, it is finished! The entire point of the exercise was a proof of concept on an accurate modern emergency vehicle lightbar, and boy oh boy did I learn a lot along the way. I’ll list those things after the video.

As the prototype of what is sure to be many incarnations to come, I dub this ’07 Ford Shelby GT500 my ‘Demonstrator‘! Please ignore the 8xAA battery pack on the side. Normally, this car can be powered by a 9V that fits nicely into the engine compartment, but I was plumb out of 9V batteries. Yes, there’s some in the house smoke detectors, but Murphey’s Laws have taught me a thing or two, so I left those 9Vs where they were 🙂 Anyways, using a 8xAA power supply tested the circuitry against a 12V source, so it’s all good! Enjoy:

Demonstrator: 1:24 Model Whelen Liberty Police Lightbar from claymore1977 on Vimeo.

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Update: 1:24 Model of a Whelen Liberty (44″) lightbar

The lightbar project work continues!ModelWhelenLightbar-Crop01 All the proper ohm value SMD resistors *finally* arrived in the mail, and a few short evening work sessions later, the resistors are in place, dud LED light modules replaced and leads carefully soldered in… we have an operational Lightbar!

Now, the front 3 Red and 3 Blue are electrically different than the rear 3 Red and 3 Blue, so add in the working center takedown and 2 alley lights, there are 15 independent LED modules on this bar. However, the software that was on the MSP430 I hooked them up to only was written for the front 3 Red and 3 Blue only, so the bar is not flashing at its full potential…. yet!

Here’s a short video that’s a bit out of focus. I didn’t catch the focus issue when I uploaded it because it was well past midnight 🙂 Once I update the software I’ll film a higher quality version.

1:24 Model Whelen Liberty Police Lightbar from claymore1977 on Vimeo.


TI: Yet More Free Samples

In between orders of Texas Instruments Launchpads evaluation boards from Mouser or Newark, Free Samples from TIdon’t forget that TI has a free sample program that can get you a couple free MSP430 chips of varying models. Combine the raw chips with the ability to power and run MSP430’s off the red Launchpad board, and you can have quite the small army of animation and automation circtuis deployed on your layout in no time and very low cost!

Just please remember to keep TI interested in manufacturing the MSP430 processors by actually buying a few now and then. I think that if the hobby of model railroading can provide a significant enough demand for the MSP430 line of microprocessors, then we could help keep the prices low and increase the online support for the Launchpad based chips. Currently, there far more resources for the Arduino. Some of which can be ported to the Launchpad, some cannot.


HOWTO: MSP430G2 in a Standalone Environment

So it dawned on me that the TI MSP430G2 Launchpad Evaluation board isn’t very small and probably wouldn’t fit in any models smaller than G scale. I also realized that buying a bunch of the Launchpad Evaluation Boards at $10 is still cheaper than other alternatives, but not as cheap as buying the raw MSP430G2 chips by themselves (MSP430G2553 is about $2.50 for just the chip). Therefore I set out on an endeavor to figure out how to minimally power an MSP430G2 chip without the Launchpad Evaluation board.


Turns out, it’s ridiculously easy.


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TI Launchpad Powered Off Of Batteries

So it turns out that powering a TI Launchpad off of something other than the USB Power (I dunno, say batteries?)TI Launchpad Powered Off Of Batteries is very very easy. All you need is to get a power supply that can provide anywhere between 1.8 to 3.6Vdc and then hook it up to the VCC(+) and GND(-) pins on a launch pad. So far, I’ve successfully tested this with a set of two AAA batteries (1.6Vdc x2) and also with a single CR2032 battery (3Vdc)

The only issue I can see is the minimum voltage required for some LEDs. For instance, high intensity Blue and White LEDs require a higher minimum voltage of 2.8V to 3.6V (avg 3.2V). Should battery supply voltage drop low enough, certain LEDs may fail to illuminate.

Over all though, it’s Easy Peasy!