Since they have goeetn into the small sizes, I have been using LEDs for panels, locomotive lighting, and signals. The first time I saw a tri-aspect target, I had to try to imulate it. I did this by taking a three-wire LED, putting a resistor on the common, and tried switching. Got red, then got green-however, by energizing both ungrounded leads at the same time, I was able to get a (sort of) amber tone. By building my signal system with current sensors, etc.; I was happy. HOWEVER... This effect can vary with different product-one mfg'r to the other, as I found out. Also, a caveat: Go slow when experimenting, and try not to get too low on resistance value. Good Luck.
You should look for Mel's comments on 3 color led's. He uses different resistors for different colors
Henry
COB Potomac & Northern
Shenandoah Valley
Well, in a way it is - it is made up of 3 (quantity) color LEDs, not a 3 color (type) LED. Which is better, - the best you ever get out of the 3 wire bicolor red/green LEDs is a kind of sickly orangish color. With the advent id ultra tiny LEDs, now they can put 3 microsocopic individual LEDs on one small board and you get an actual dedicated yellow LED for the yellow color, instead of trying to mix it by varying a red and green together. Finally searchlight signals can have the same colors as a 3 light signal head.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Thank you everyone. The searchlight I bought is similar to the WeHonest Signal. I will buy the manual switch recommended for that kind of signal. I was not aware that there were three LEDs in each head as the searchlight was advertised as being made of three colored LEDs.
Finally, I agree with everyone that 4 is FOUR. My bad. ☹️
Guy
Modeling CNR in the 50's
I was going to chew on Mark for accusing Guy of not being able to count to 4. The video link I posted shows only 3 leads, but on closer inspection of the WeHonest signal, there are 2 lights, 6 wires connected to resisitors and 2 black wires hiding underneath. Then I re-read the OP post and 4 is 4
If there are 4 wires, WeHonest has a plan and a manual switch for that.
You say each LED has THREE wires .... red / yellow / green / black. That would be four wires. I'm assuming it is similar to the BLMA signals that use chip LEDs and there are three separate LEDs in the head. The black would be common and the other colors would match the appropriate color.
To attain three different colors, you would need either a multi-position switch or a pair of SPDT switches.
If using the two SPDT switches, feed the power into the first switch. Up position would feed the red light, down would send the power to the second switch which would feed either the green or yellow.
Mark.
¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ
My favorite Ebay seller name, WeHonest, sells a signal control board and IR sensors and cables. I have not used these devices.
https://www.ebay.com/itm/1-x-model-railroad-automatic-signal-controller-train-detector-master-board-/153342866092?hash=item23b3f272ac
https://www.ebay.com/itm/1-x-one-join-two-IR-sensor-split-wire-connector-block-signal-controller-/401707455330?hash=item5d87a15362
I would use a 3 position rotary switch to control each position. I'm not savvy in posting electrical diagrams but I'm sure someone here can add to my comment.
It's not obvious to me how a DPDT switch could control 3 separate functions. This is how tri colored Leds work.
I just received a searchlight with two lights. Each light is a tri colored LED. Each LED has three wires: one green, one red, one yellow and one black. For now, I want to control the lights manually. How can I do that with a DPDT Switch for each light?
The searchlight was bought on eBay and came without any instruction.