Resistors resist the flow of current, thus reducing the voltage or current in a circuit. Current can flow through a resistor in either direction. These (in the small sizes) are round with wires at either end, the barrel of the resistor has colored bands on so that if you know the code, you will be able to read the value of the resistor.
Diodes are devices that will allow current or voltage to flow in one direction only and will block it in the other. Physically they look like resistors, they are usually all black, may have some code on them and will usually have the (+) end marked with a silver band. There is some current loss in the pass direction, but that is so negligible as to be invisible to most circuits. These may also be called rectifiers.
Bridge or Full-Wave Rectifiers may be thought of as four diodes in one case. There are four pins tow of them receive the AC or at least raw signal, and two pins provide (+) and (-) output. I said raw input, since I use these full-wave rectifiers on my passenger cars, that way no matter which way the train is going, the correct polarity is always passed through to the LEDs that I use for lighting.
Diodes ad Rectifiers are sized by what power they can pass before they are destroyed. Bigger ones will cost you more money and take up more space but will not harm you if you do not need them, therefore buy the smallest ones that your circuit will use. (Well rated for 2x your design power). I buy them in bulk 100 for $1.00 or so.
Resistors on the other hand have many different values both in the amount of current they can handle (usually expressed as watts) and the amount of resistance they introduce into the circuit (expressed as ohms Ω)
I have been using 1/2 watt / 5.10Ω resistors embedded in my tracks to slow trains down as they enter the station. They might have a much wattage for what I am doing, but the length of time that they are actually in use is nominal, and I was told by our engineering department that bigg
As you say, well worth it. That is outstanding work. LION models the NYC Subway, there are no PRR Position signals, but hundreds and hundreds of three lamp target-less masts. That is also boring but necessary, and I do not have the same levels of skill that you have shown.
Sorry for the long pause. Been away from the putr.
The digitrax SE8C is designed to drive the LED’s without droppign resistors.
The bridges in the pics earlier are driven directly from the SE8C through a TSMK (Terminal Strip Mounting Kit). The TSMK has required 100ohm dropping resistors installed in them.
To put your mind at ease though when you’re ready, hook up one of the LED’s to the TSMK.
Note that you cannot use a multimeter to get an accurate voltage reading. The outputs pulse very quickly back and forth between 2 different commons which makes throws the reading off.
