The Rusty Spike

A Railroad Fan's Website

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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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Chasing Lights (74HC595 Register + TI Launchpad)

Okay ladies and gents, here’s a Chasing Light project using a single Shift Register (74HC595) and a TI Launchpad. (I’m currently following a line of research using the Shift Registers, but there is an easier way to do this with just a Launchpad alone.) It can be easily adapted for many uses. Examples include, but not limited to:

  • Theatre Signs
  • Airport Landing Strip
  • Eat At Dave’s Signs

This particular Launchpad project uses an external device called a Shift Register. Simply put, it’s a device that remembers the 1 or 0 you just put into. If you put another 1 or 0 into it, it shifts all the existing saved 1’s and 0’s over one slot and adds your newest value in. It can hold 8 values, hence the term 8-bits.

Here’s what it looks like when its all put together on a breadboard:

Chasing Lights v1.0 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.

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In Lieu of a Breadboard: PCB LED Test Harness

PCB LED Test BoardHere is a project idea for some of you. If you are anything like me and you are experimenting with an Arduino or TI Launchpad for the purposes of your model railroad, then you likely find yourself adding and removing LEDs and associated resistors to/from breadboards over and over again. So it dawned on me: Why not solder some LEDs and appropriate resistors for a 3.3V source onto a spare PCB project board and slap some headers on there? Well, since I was waiting for some parts for other MSP430 projects, I did just that!

 

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Basic Electricity 101: American Wire Gauge Chart

gauge Diameter Inches X-Section (in2) Diameter mm X-Section (mm2) Ohms per 1000 ft Ohms per km Maximum amps for chassis wiring Maximum amps for power transmission
OOOO 0.46 0.166196 11.684 107.222966 0.0490 0.16072 380 302
OOO 0.4096 0.131772 10.40384 85.014313 0.0618 0.20270 328 239
OO 0.3648 0.104524 9.26592 67.434449 0.0779 0.25551 283 190
0 0.3249 0.082909 8.25246 53.489874 0.0983 0.32242 245 150
1 0.2893 0.065736 7.34822 42.410073 0.1239 0.40639 211 119
2 0.2576 0.052119 6.54304 33.625122 0.1563 0.51266 181 94
3 0.2294 0.041332 5.82676 26.666068 0.197 0.64616 158 75
4 0.2043 0.032782 5.18922 21.149928 0.2485 0.81508 135 60
5 0.1819 0.025988 4.62026 16.766312 0.3133 1.02762 118 47
6 0.162 0.020613 4.1148 13.298485 0.3951 1.29593 101 37
7 0.1443 0.016355 3.66522 10.551272 0.4982 1.63410 89 30
8 0.1285 0.012969 3.2639 8.367166 0.6282 2.06050 73 24
9 0.1144 0.010279 2.90576 6.631690 0.7921 2.59809 64 19
10 0.1019 0.008156 2.58826 5.261633 0.9989 3.27639 55 15
11 0.0907 0.006461 2.30378 4.168566 1.26 4.1328 47 12
12 0.0808 0.005128 2.05232 3.308224 1.588 5.20864 41 9.3
13 0.072 0.004072 1.8288 2.626861 2.003 6.56984 35 7.4
14 0.0641 0.003227 1.62814 2.082036 2.525 8.282 32 5.9
15 0.0571 0.002561 1.45034 1.652131 3.184 10.44352 28 4.7
16 0.0508 0.002027 1.29032 1.307674 4.016 13.17248 22 3.7
17 0.0453 0.001612 1.15062 1.039845 5.064 16.60992 19 2.90
18 0.0403 0.001276 1.02362 0.822967 6.385 20.9428 16 2.3
19 0.0359 0.001012 0.91186 0.653072 8.051 26.40728 14 1.8
20 0.032 0.000804 0.8128 0.518886 10.15 33.292 11 1.5
21 0.0285 0.000638 0.7239 0.411587 12.8 41.984 9 1.2
22 0.0254 0.000507 0.64516 0.326919 16.14 52.9392 7 0.92
23 0.0226 0.000401 0.57404 0.258815 20.36 66.7808 4.7 0.729
24 0.0201 0.000317 0.51054 0.204722 25.67 84.1976 3.5 0.577
25 0.0179 0.000252 0.45466 0.162360 32.37 106.1736 2.7 0.457
26 0.0159 0.000199 0.40386 0.128105 40.81 133.8568 2.2 0.361
27 0.0142 0.000158 0.36068 0.102176 51.47 168.8216 1.70 0.288
28 0.0126 0.000125 0.32004 0.080448 64.9 212.872 1.4 0.226
29 0.0113 0.000100 0.28702 0.064704 81.83 268.4024 1.2 0.182
30 0.01 0.000079 0.254 0.050672 103.2 338.496 0.86 0.142
31 0.0089 0.000062 0.22606 0.040138 130.1 426.728 0.7 0.113
32 0.008 0.000050 0.2032 0.032430 164.1 538.248 0.53 0.091