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Discussion Starter · #1 ·
Hello Gang.

I have an old O gauge (not o27) track and lionel transformers.

Instead of those weight trigger contacts to trigger a crossing gate or flashing signal crossing, I want to use isolated track.
One of the old timers at a train show explained to me that if I use isolated track, and put resistors on the accessory, it will perform better than the weighted contact. He sold me the resistors (i think they are white/black/gold/orange band resistors).

I have two resistors.
I have two sections of Isolated track.
And I can't remember what do do next...

I think I put the resister between two of the 3 terminals under the accessory, and I can put a lock-on on the track, and wire the accessory to the lock on but I can't remember the sequence/diagram of the wiring.

Can somebody spell it out for me that a bonehead can understand?
 

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I can't imagine what the resistors are for. FWIW, here's a schematic of a board I make do do the insulated track function. This offers bounce protection and various powering options. It also offers contacts for the track occupied and unoccupied so you can power things like red/green signals.

Here's some examples and the wiring diagram.

Insulated track sensor diagram

Track Presence Sensor Rev 1.2 Schematic.png


Insulated track sensor board

Track Presence Sensor Signal Driver Top View.jpg


Insulated track sensor typical signal wiring

Schematic Track Presence Sensor Signal Driver Track Power.png
 

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When no train is on the isolated section, the resistor is shunting the red lamp so the green gets voltage via the red lamp and it's shunt. When the train connects the isolated rail to ground, the red gets full power (as well as the parallel resistor) and the green is shorted to ground (off).

Yesteryear's solutions were an education in simplicity.
 

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Discussion Starter · #7 ·
When no train is on the isolated section, the resistor is shunting the red lamp so the green gets voltage via the red lamp and it's shunt. When the train connects the isolated rail to ground, the red gets full power (as well as the parallel resistor) and the green is shorted to ground (off).

Yesteryear's solutions were an education in simplicity.

So If those terminals are numbered 1,2,3 from top to bottom.
The resister would be wired between terminal 2 and 3.
Then,
I would wire my transformer directly to terminal 1(-) and 3(+).
Then use a lock on to send a ground signal from that insulated rail to terminal 2 (-)?

-JJ
 

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So If those terminals are numbered 1,2,3 from top to bottom.
The resister would be wired between terminal 2 and 3.
Then,
I would wire my transformer directly to terminal 1(-) and 3(+).
Then use a lock on to send a ground signal from that insulated rail to terminal 2 (-)?

-JJ
That's correct. For the transformer + I'd use the accessory voltage, not the variable track power. That will give you a constant brightness regardless of train speed. That also means you need to understand variable +, Accessory + and the common terminals on your transformer (they get mixed on various Lionel pre/postwar conventional transformers).

Also, please re-post the color codes on your resistors. Your original post had the colors out of order (gold, the tolerance spec, would always be last). The color order makes all the difference when figuring the resistor's value. And they need to be 5+ Watt rated resistors for this application.

"A picture is worth more than a thousand words."
 

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29 Ohms, 5% tolerance. Looks to be a 1/4 or 1/2 W resistor. When using the accessory voltage (14 or 16 V) and the train parked on the isolated track, it will likely burn up after short time.

You can try it to see if it is the right value. That is, do the bulbs light reasonably well with that value resistor. And does it heat up rather quickly to the touch. Once we know that, I can point you to a resistor of suitable wattage on eBay for a buck each (like the gold or white one depicted below). The only issue is you have to wait for "The slow boat from China" to get 4+ weeks.

Lionel included a resistor in some of there block signals . As shown below, the resistor (covered in white insulation) is a heavy duty wound type.

Block Signal.png
 

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That's a 19 ohm 5% resistor.

Your correct (always had trouble with the colors).

I was thinking maybe the OP should try them in series for the first test given they're low power resistors. Using an accessory post at 14 V, your looking at ~3/4 A and ~10 W through one resistor. With the two resistors in series, that goes down to ~.4 amps and 2.8 W per resistor. It really depends on the green's bulbs resistance.
 

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Discussion Starter · #14 ·
I bought a new, in the box lionel isolation track from a seller on ebay. Turns out, it wasn't isolating. Stuff got HOT! Sparks flew! I took it to the garage, took the track apart and made sure it was actually isolated, put it back together.

I hooked everything up again and it seems to work better without the resistor. The resistor jumps the connection between the two terminals so a wee bit of current passes through.

It's a 151 Semaphore signal. I also hooked up a highway flasher and again, it works fine when the train rolls over the isolated track.
 
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