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Monday, February 22, 2021

Control Panel ~ Cable Provider

 Constructing a Cable to Connect the Control Panel to the Layout.

A quick disconnect cable will allow the control panel to be removed from the layout to ease the transporting of the layout.

Recently I have installed the Octocoder and Singlet servo decoder and controllers to the control panel. Now I need to wire the controllers to the turnout servos on the layout. This is what this cable will be for.

This is the 37 pin twist-on cable connector that I'll be using for the cable. I'll only be using 24 of the pins for the turnout control. The remaining pins will be used for anything else on the layout that needs to connect to the control panel such as the on/off switch for the streetlights.

But first- I need to mount the connector to the layout. So I fabricated this wooden mount that will mount under the layout. The small part of the connector (center) fits into the hole in the mount and screws on. Wires from the servos (and anything else) connect to those pins. The larger part of the connector (right) twists on to it.

Now comes the fun part:
Soldering on the servo wires. But here's the problem. Whoever originally bought this connector installed the pins before the wires were soldered on (I got this connector second or third hand). So I have to solder the wires on in very tight quarters.

Dense. My first try I started with pin #1. But after the first row of wires were installed I wasn't able to access the second row. So I de-soldered the wires and started again. This time I started with the last pin and worked backwards. Which worked just fine. But keeping track of what wires are where is now a challenge!

Gold pins. According to the NASA tutorial I watched on soldering connector pins, the gold from the pins need to be removed first. Which I tried but failed at. But I'm not building a rocket ship- my layout isn't going to be exposed to the extreme conditions of avionics, so I decided to just leave the gold. A stripe of melted gold can be seen in the solder in the photo on the left. Hopefully this won't come back to bite me. If one of those wires detach from the center of the wire bundle there isn't room to solder it back on. Unless maybe I can fit my resistance soldering electrodes in there like this cool "old school" video demonstrates.

A Pin Designation Chart to help keep track of what wires go where. The turnouts are named (e.g. 1AR = 1st turnout, Block "A", Right turn) that coincide with their names with the Railroad & Co program. And where on the Octocoder the wires plug in to.:

And we got a cable! It's kind of messy, so....

Tucking the wires into this Split Wire Loom should make it all neat.

Much better. Let's plug it in...

Under the layout shot. Success- It's in there! But the cable is only half of it. Now comes wiring the receptacle. The servo wires will radiate out from here to the turnouts as they are installed. A lot of work that will never be seen. But it will be felt. Each trolley navigating its own route should be very cool to see.
Yes sir! 
Very cool to see.


Monday, February 08, 2021

Electrolier Electrical Grounding Test

 Question: May AC and DC share a Ground?

Specifically, may the 3 volt DC from the LED lamps ground to the same post that is powering the 15 volt AC trolley trolley overhead?

These Electroliers were a lot of work to construct. I really don't want to blow out the bulbs. But they perform two duties. One, they are street lamps that illuminate. Second, they provide support to the overhead trolley wires. And that's where the AC+DC concern comes in. 

    There wasn't a concern when the layout was a DC layout. 3 volt DC and 15 volt DC grounding together is fine. But now that the layout is DCC, the overhead is AC.  So the DC LED's in the lamp are grounding to the AC pole.

So before I install the trolley span wires between the Electroliers, I'm going to perform a little test first to make sure this AC/DC mixture doesn't blow the LEDs:

Here is the set up:

1. Clamped a brass pole the the layout.
2. Installed the 3 volt DC circuit:
    a. Soldered the negative lead of a LED to the pole.
    b. The positive lead of LED with resistor is connected to a battery.
    c. The negative lead of the battery connected to the pole.
3 Installed the 15 volt AC circuit:
    a. Soldered a wire from DCC command station to the bottom of the pole.
    b. Soldered a wire from top of the pole to the overhead.
    c. Connected a return wire from the track to the command station.

    Then I powered everything up. The LED lit. A trolley was placed on the track. Turning its headlight on and off as well as starting and stopping the car seems to have had no effect on the brightness of the bulb. Which means both AC and DC was flowing through the brass pole with no visible effects to the LED. So I think we are all good for safely installing span wires between the Electroliers.

Yes sir! All good to safely install span wires!