Some of you forum members provided a tip on connectors to my good toy train buddy. He got hisself one at RS and here’s the photographic proof in the pudding.
His layout is fully collapsable. Here’s what he wrote in an email:
"Here’s what one of my 25-pin quick-disconnect electrical connectors looks like with wiring leads soldered. It seems like a profusion of wires, but alternating with black and red-insulated wiring helps you to sort them out quickly. You’d be surprised how quickly each lead is committed when wiring multiple blocks, three-wire switch machines, accessories, and lights! I have a similar connector for the third section of the modular Port of NY & NJ layout.
Once all wiring is completed, metal covers clamp on each of the male and female connectors so that you pull the connector’s cover apart to separate the halves–and not the soldered leads!
This is a good way to develop soldering proficiency in a hurry … and a good reason to own a professional-quality wire-stripping tool!
I would (and have) advised against using what looks like rather small wire for powering trains (“multiple blocks”). The wire should be large enough to stand the fault current that the transformer can deliver, without starting a fire.
That kind of connector is also not designed for high current. They are typically rated at only a few amperes.
Rather than tell my buddy NOT to use them, can I nicely let him know they may not work by reminding him of the amperage that may need to pass thru the device?
If so, pls let me know:
What is the max amps (I know it depends on what he’s using/running, but can you give me an upper conservative ballpark figure?
Does radio shack rate these devices on its packages and if not, how can a novice rate a particular device?
This I feel may be more constructive feedback than just telling him he’s making a mistake and they look terrible.
The current rating varies from 1A to 7.5A depending on the design & quality. The 1A rating was for an IDC connector and is mainly due to the small size of the IDC ribbon cable (28 or 30 gauge). Most wire mount connectors can handle 3A but you will have to look at the manufacturer’s data sheet to find the actual current rating.
Also, the wire mount connectors are usually limited to about #22 gauge wire maximum, which is good for about 3.75 amps.
They should be fine for switches & control. For track power, you should use a heavier duty connector or parallel 4 wires together (4 hot & 4 common wires per power block).
I searched Radio Shack’s site and found a category of connector that’s suitable for carrying the kinds of power you’d expect to find on a toy train layout.
thanks, guys, In a couple hours I’ll send him an email like this (pls make corrections where needed). He’s a great friend of mine, a retired naval aviator and my former boss.
Gordy,
That is a great wiring job. A couple of comments.
While the connector you wired is great for accessories and other items that require low voltage, I would be a bit concerned about using that particular connector to carry the high amperage used for toy trains, unless that component is specifically rated for such. Toy train current varies from about 2 to 8 amps, depending on a lot of factors.
Most wire mount connectors can handle 3A but you will have to look at the manufacturer’s data sheet to find the actual current rating.
Also, the wire mount connectors are usually limited to about #22 gauge wire maximum, which is good for about 3.75 amps.
They should be fine for switches & control. For track power, you should use a heavier duty connector or parallel 4 wires together (4 hot & 4 common wires per power block). Molex is an example of a connector intended for high voltage.
Molex sockets are difficult to find. The plugs can be scavenged from dead computer power supplies, so they’re plentiful. Sockets can be scavenged from dead computer fans, but those sometimes only have two of the four connections. And a lot of fans use a different plug, especially recent fans.
The Radio Shack connectors I linked are a reasonable alternative.
The Radio Shack connectors are Molex, or direct substitutes. Fry’s carries a wide variety of Molex, if you have that store where you live. The Molex connectors come in two pin sizes. I would use the larger for track power.
The Molex pins are designed to be crimped to the wires; but I always solder the crimp. You can crimp and solder a Molex pin onto a stranded 14 AWG wire without much trouble. Solder the crimp to the conductor before wrapping the strain relief around the insulation, so that the heat does not melt the insulation under the strain relief.
The Molex male pins are protected better than some by a skirt around the connector. But it is still a good idea to assign the sex of the connectors so that the male side is dead when the connectors are unplugged.
The connectors and the wire should both be sized for the fault current, not for the typical train current. The fault current is what the transformer can deliver before the circuit breaker trips, not what the train uses in normal running. You want to protect your wiring when a derailment or other short circuit causes that large fault current to flow. Many large transformers can put out as much as 15 amperes, which requires 14 AWG wire to be safe. You can get by with 16 AWG, which is good for 10 amperes, with a small transformer; but I would advise not going below that. Since 14 AWG is used for house wiring, it is cheap and readily available. I highly recommend it.
High voltage is not a concern for toy trains. Virtually any connector or wire can handle the voltages we use.
Here are specs for the 25-pin connector … rated at 5 amps and upt to 500v AC for up to one minute. Given substantially lower voltage, shouldn’t this be okay? (I know its the amperage that is the real concern).
Train runs fine on the block powered through the connector I’ve already wired … but better safe than sorry!
Again, the voltage rating doesn’t matter. And that the “train runs fine” doesn’t mean that it is safe. That connector with 20 AWG wire is okay for a transformer that trips at 5 amperes, if that’s what he’s using, with an intention never to get something bigger.
may be I wrong, but this kind of transformer are electronic , so when you have a shotcircuit the transformes atomaticly try to increase the voltage and current. so you need some thing little bit strong.
