I saw this on a video illustrating Kato power routing on #4 and #6 turnouts and do not know what it is or how to go about making one, or something more basic. I am considering adding something like this to easily show when a siding is powered or not. Is there a more simple method for doing this? Looking for a miniature LED that would light when power is routed to the siding. Thanks in advance, CBG
Picture is kind of small....how about a link to it maybe. Looks like it is setup maybe for DC. Are you DC or DCC? When you say small LED there are really small ( .020" long) SMD LEDs. Where are you going to put it? Sumner
i did a similar build but mine is for DCC very simple to do.. this is DCC only .. but my leds all have built in resistors so this could work on dc .
Sumner, I switch between DC and DCC and am thinking about putting the lights in Kato bumpers or something similar. The link is . Sidney, this looks like exactly what I want to do. I will purchase some small LEDS and give it a try. Not being very knowledgeable in electronics I would need LEDs with resistors as you mention for this to work on both DC and DCC depending on my power source correct? Anything specific I need to look for in resistor type? Thank you both very much for your replies.
Hopefully someone else will also step in here with a solution. First when it is DCC things will be easier. Something like Sid is suggesting will work although some will also say it would be better to also have a diode in the circuit. DCC is similar to AC and the current is constantly switching back and forth so the LED is seeing one lead going from positive to negative and the other lead of the LED is switching the other way. The LED is actually flickering and going on/off repeatedly. It happens so fast that to the eye it looks like it is always on. The LED is a diode so is blocking the flow one way and is off and letting the current through going the other way and on. This can over time, don't ask me how much, hurt the LED as it isn't designed for this. If you put a diode in series with the resistor and the LED it will block the current in one direction and is designed to do that. It has to be turned the right way in the circuit or the LED won't ever come on as it will block the current in one direction and the diode will block it in the other direction. Even though the LED is off half the time also using the diode it will appear to be on. Another option and I used it ( HERE ) is to use a bridge rectifier but I won't go into that (see the link) and don't feel it is needed for what you are trying to do. I don't see an easy answer for when the track is DC. If the throttle supply is set to say forward and the resistor/LED (don't need the diode) is wired one way it will be on. Problem is that if the throttle is then reversed and the current on the track is reversed the LED isn't going to come on since again it is a diode and will block the current (again probably not good for the LED so maybe a diode would he a good idea). Two LEDs would solve the problem but you probably don't want to install two although you can get extremely small ones, like ( HERE ). Also you don't have to get an LED with a resistor but can put a resistor into any LED circuit. Different options for the resistor are out there and it isn't hard to do. Would also be nice to know what the track voltage would be for both the DCC and DC. Voltage will play a part in choosing the resistor although you could use a larger one, say 1K for the DCC and be good for most voltages. When it is DC the intensity of the LED will be set by the throttle position just like the headlight on the engine. I'm sure there are other solutions but not as simple as a LED and resistor. As I said at the beginning above hope someone else sees a simple solution. Sumner
Kato does sale lighted bumpers. They are track powered and DCC and DC compatible. 20-063: 20-064: Another option would be to install LEDs on the turnouts to show the direction the turnouts are thrown. This circuit works for DC and DCC: And this simplified circuit is DCC only: And installation pictures:
This is something many people ignore. Red/green/yellow LEDs are pretty tolerant of reverse voltages and can last a long time like this. White LEDs, on the other hand, are much more sensitive to reverse voltages and will likely not last long at all. I've seen instances of people using white LEDs for locomotive headlights where they get them installed and tested fine, but after a few minutes of running the LED dies because of the lack of reverse voltage protection. If you use two LEDs of the same color, you can wire them in parallel, but reversed polarity - you still only need one resistor and you do not need blocking diodes. If you want only one LED another option is a bridge rectifier.
That is what I did for a light on my turntable that lights any time there it power to the track on the turntable. Knowing more now I could of probably gone with the simpler circuit using only a diode and resistor but this wasn't hard to build and wasn't expensive. You can see it working in the video ( HERE ) but this wouldn't solve the DC situation. Doesn't look like an easy solution there. Me, I would use two of the very small 0201 LEDs next to each other and the single resistor in the circuit like you mentioned or two larger LEDs depending on where they were going. Sumner
WOW! Excellent information and detail, thank you all for the input. Considering my current skill level I think the plug and play option of illuminated bumpers will fit my need initially. On a brave day I will give one of the circuits outlined a try. Thanks to all again. CBG
Correct! I checked the absolute maximum reverse bias spec on a green SMD LED recently and it was only 5 volts. Wouldn't last long in a DCC circuit. Having the LEDs paralleled but reversed limits the back bias to the forward bias voltage on the opposite diode. Here is a schematic (literally drawn up on the back of an envelope) that depicts the solution: PXL_20230123_163318918 by olequa posted Jan 23, 2023 at 8:40 AM George Edgewood, WA
Incidentally, this circuit works on both DCC and DC. With DCC both LEDs light. On DC, one or the other lights up, depending on the DC polarity. You could use this circuit to indicate turnout state by connecting it between the frog and one of the stock rails (two circuits required, one could use red LEDs, the other green). George
