2015-01.2: TMTV January 2015 Edition - Act II

11 Jan 2015

Average: 5 (20 votes)
31:13 - January 2015 Act II - Back to the basement: wiring (2015)

In part 7 of Back to the Basement, Miles Hale shows us tips for wiring track and switch machines, and introduces us to a revolutionary device: the A-Frame-O-Matic.

Act III: David Jacobs' On30 Michigan-California Lumber Co. ...

Own a copy of this video for just $3.49

Go to Act III


Miles didn't mention that the cheap VOM (volt-ohmeter) won't give an accurate reading of the DCC voltage. That's because the cheap VOM assumes the AC waveform is sinusoidal. The DCC waveform is a square wave. Only an expensive "true rms" meter will give an accurate reading. That being said, if all you are doing is determining if the DCC is alive, then the cheap VOM will work.

But definitly don't use the cheap VOM to calbrate the DCC voltage level. The danger here is if the cheap VOM reads low. In this case, if you re-adjusted your DCC voltage, the actual voltage would be higher than you think, risking damage due to overvoltages.

Hi Miles,

At the beginning of your talk about using suitcase connectors (acutally known officially as insulation displacement connectors IDC's) you mention your main bus is #16 wire.  Later you refer to it as #14.  Your connectors #558 are correct for #16 wire, but if your bus is #14, you should be using #905 connectors, which are listed for 14-18 wire on the through run and 18-22 on the tap wire.  I suspect the 558 might stretch onto #14 wire, but why not use the correct size?  Plus, the 905's are cheaper!  I get mine from my local Grainger store.

Also, on your buzzer, a 9 volt one isn't really necessary.  I built mine with a 1.5 volt battery case from Radio Shack, but recently had to replace it with a 3 volt buzzer to get a louder buzz.  Getting old is a bit of a pain.

Rod Smith

Georonn's picture


Another very informative episode.  Great job with it.  I do agree with an earlier comment about using either a true RMS meter to measure DCC voltage, or even using the RRMeter from Tony's Train Exchane which is designed to measure DCC volts and amps.

I am wondering how long it took Miles to discover he had wired a short in his sub-bus?  I noticed some scenes were reshot with the white to white connection correct, but the majority were shot with the white to black short in place.  Like Miles, I too have to slow down when doing wiring or I make the same mistakes he did.

TMTV Station Agent's picture

Bonus marks to you for paying attention!  :)  

A really good reason to use the simple short-testing buzzer that Miles recommends in this segment.

Thanks again, Miles, for another great installment! I really enjoy watching these.


Some very useful & informative tips.

great segment. I would like to see more on wiring.  Not mechanics, but more on how to design the wiring. For example, why use a sub bus?  How to wire reverse loops.  What size are blocks and why have them?  There are many similar topics we could benefit from.  

Ken's picture

Yeah, it's just the B Roll that shows the short, so you only see it in the close up's.

Something he touched on, but didn't really go into detail about, is wiring standards for devices. Miles uses the gray and orange twisted pair for tortoises. If he always uses those two colors, and always connects them to the tortoise the same way, he now has a wiring standard for tortoises. This means that if he has a problem with a particular tortoise machine, he only has to look for the ornage and gray twisted pair for troubleshooting. He can ignore all the other wires of any other colors, or color combinations. This makes life SO much easier when things aren't working.


Good explanation of how the DPDT direction changing switch works but wired like that it is one bump away from a short circuit. I always leave the insulation on the wire for the crossed sections. This can be done by baring a section of wire, folding the wire back 180 degrees to leave a bare section of wire to twist and solder to one corner connector. Then, take that wire, trim and strip to solder to the diagonally opposite corner.


Great job of explaining difficult electrical issues that are not known by those like myself who have never gotten into this stuff before.  Your videos Miles are extremeliy helpful and full of tips and suggestions to make the job easier.  I look forward to your future videos.  They are a great addition to MRH.