LED question

just make sure you are 12 volts DC or less. I power hundreds, (literally hundreds) of LEDS from a 9 volt power supply. Running the full 12 is pretty bright. Don't hook up to AC without some modification to the project.

LED's are current driven DC devices. If you have the dropping resistor in series, the standard way of operation is to run them on DC. However, I have experimented driving LED's with the resistor an a 12V AC voltage and so far my LED outdoor lighting is working fine afterof the dropping resistor. three years.

Note :If the LED "bulbs" are rated for 12V I would run them at exactly that.  Going higher or lower in voltage requires changing the inline resistance

They are dc items and rectification is needed most of the time . They are also diodes, so back to back with another led or diode, cathode to anode, and resistace, can give you ac capability. (if 2 leds, both light on ac, on dc only one lights; which lights up is per dc polarity being used. I.e. thats how some have directional headlamps wired too)

  Your's have resistors already, but they are also selected for use at a specific voltage range; what would the range be? If as a set, and that range is lower than the Z4k voltage, you will need another resistor added or swapped in to increase the resistance for the new voltage accordingly, or you need to regulate the voltage by other means, but it has to fall in range.

"Dialing" resistance in isn't really hard or pricey. A variety pack of resistors becomes a test tool (start with lots of ohms at max voltage and reduce ohms to get brighter)

If your LEDs are the "universal" type from Evans Designs, they have a bridge rectifier and capacitor (converts AC to DC) and a current limiting resistor which allows them to run on 7-19VAC.  So you can use either the 10V or 14V posts on the Z-4000.  If your LEDs are labeled to run on 12VAC, then use the 10V posts.  But make sure they are labeled to run on AC.

If they are only wired with a current limiting resistor, they should only be run on DC Voltage.  They will work on AC but their life will be a lot shorter. In that case, connect a 1 amp bridge rectifier AC leads (~) to the 14V posts.  This gives you around 11VDC.  Connect your LEDs to the the plus and minus leads of the bridge.  If the an LED does not light, reverse the wires. The rectifier will handle about 30 white or blue LEDs or 50 red, green, or yellow LEDs. Use a larger amperage rectifier if you need more LEDs.

See my article on LED lights in the December 2017 OGR Magazine for more information about powering LEDs.  That issue is a "Merry Christmas" free download from the good folks at OGR Magazine.

Bob Glorioso

You can attach the lights to a Buck Converter, where you can adjust the ouput voltage, I use it set to 10 volts for the passenger cars.    Here is the link for the convertors:   https://www.ebay.ca/itm/162724139001, DC in and DC out, could to go I use a 2amp rectifier for DC in, then connect your lights to DC out.  Adjust brightness level and your done...

Marty

I am wondering if I can run wires from my z4000 fixed output to a terminal block and from the terminal block to the LEDs pictured below or something similar.   I am thinking it won’t be so easy

i did look at Evans designs and see they sell four LEDs for $10.00 that look like they are ready to wire straight to the terminal block 

i want this to be as plug and play as possible 

It would.be as easy as a few dollars for a bridge rectfier and maybe an extra diode or two to knock voltage to 12vdc max.. The "hard part" (if you can call it that) is the resistor, which they include. That dials them in for up to 12v. Adding another resistor would increase the source voltage you can use, or you could lower a higher voltage to 12v another way if you chose.

I think it was mentioned in another thread the Miller lights, etc are ac/dc ready.

Regarding your Amazon pre-wired LEDs, for O-gauge buildings, will 7" wires be long enough?  Also, this style of LED has narrow (20 degrees) output.  A crude analogy would be trying to illuminate a room with a bunch of flashlights.  What's nice about traditional incandescent bulbs is they project light 360 degrees which generally makes for more uniform, smooth lighting in buildings.

As to directly driving the 12V DC pre-wired LEDs from a fixed Z-4000 AC output, even if you get the voltage right (using resistors or whatever), you will get pulsed light. The LEDs will be flashing on and off 60 times per second.  Many people claim they can't "see" this flickering but it's there and can be annoying over time ... sort of like the eye-strain folks would complain about in traditional fluorescent room lighting (old 60 Hz ballasts vs. modern high-frequency electronic ballasts) or older CRT computer displays which pulsed at 60 Hz or so.  To that end, look into a method that includes a bridge-rectifier as suggested by others. 

Finally, have you considered using the 12V DC LED strips that come in rolls?  There have been hundreds of OGR threads on using these.  They end up costing about 2 cents per LED, they include the resistor so no fussing with tiny components, they are wide-angle for more uniform lighting, probably easier to mount in buildings, and so on.  In practice they do end up requiring some soldering of wires so not exactly plug-n-play.

In any case, if you want to use the Z-4000 AC output to drive DC LEDs, you really need "something" in between.  As you point out, if you do this "something" on an LED-by-LED basis such as provided by the Evans LEDs, it can get somewhat spendy ($2.50 per LED).  Hence, much more effective to provide this "something" once.  The something of course is any of dozens of AC-to-DC converter modules as suggested in earlier postings.  Less than $5 to drive dozens of LEDs.  So your all-in cost per LED is at least 10 times less.

Thanks Stan - that was exactly what i was looking for....sounds like converter and strip lighting is the way to go.  Soldering is not a problem...trying to put together small components is...

 

not to belabor this...but I founds LED strips and power supply separate from z4000...looks like the power supply will power all lights on the strip....once I cut strip to size for what i need for a building...5 or 6?  Then what? - Solder wires to the end and connect to the next set of lights at the next building?  So it will become a long strip with wires attaching the shorter strips of lights at each building?

 

 

I use an old PC power supply  to provide 12VDC. I wire led strips in the buildings, using  and connect groups to a bus bar terminal block wired to a switch at the control panel. You need to use the leds from the strips in multiples of three as needed for sufficient light in each building. I use these connectors at each building to make it simple to take it off the layout or even swap places with buildings. I also have long strips under the layout  and in hidden storage track areas on switches. I have yet to get to 3 amps with everything on, including the 15 buildings.

Yes. Basically wired in parallel. That's how they are before you cut them. Make sure you cut them in the right place to keep the circuit full. Make sure you get the Ac to DC converter. Make sure you set the voltage output of the converter before you connect the LED strips. (less than or around 12 volts.)

msp posted:

not to belabor this...but I founds LED strips and power supply separate from z4000...looks like the power supply will power all lights on the strip....once I cut strip to size for what i need for a building...5 or 6?  Then what? - Solder wires to the end and connect to the next set of lights at the next building?  So it will become a long strip with wires attaching the shorter strips of lights at each building?

 

 

You will notice the led light strips are oriented to three led with resistor inbetween.  Cut them to length in multiples of three retaining a resistor for each group of three.  You may wire as you describe, but might be easier to  power a terminal/barrier strip out to you buildings then connect them individually to the terminal strip.

 

lots Of good information- thanks for all the input

If LEDs are supposed to run on DC power then how was this possible?

Regulation is on the led strip, or maybe IS the rectification to D.C.... L.E.D: Light Emitting DIODE. Use back to back in opposing polarity for ac operation. Some diodes are internally rectified; some can just plain handle some ac negative waves, or flow more current, etc. https://en.m.wikipedia.org/wiki/LED_circuit

Trainlover9943 posted:

If LEDs are supposed to run on DC power then how was this possible?

They will run on AC as in the video, but the life of the LEDs will probably be shortened considerably.  

LEDs can be operated on an AC voltage, but they will only light with positive voltage, causing the LED to turn on and off at the frequency of the AC supply.  Many people notice the flicker and find it annoying.

Most LEDs have low reverse breakdown voltage ratings, so they will also be damaged by an applied reverse voltage above this threshold.  LEDs driven directly from an AC supply of more than the reverse breakdown voltage may be protected by placing a diode (or another LED, or another LED strip) in inverse parallel (opposing polarity).

   Resistor needed, but not shown in this one

Bob

Like Bob says, the reverse voltage specification on most LED chips is in the 5-7 volt range.  Since the peak voltage of the AC waveform is 1.4 times the RMS value, it's not hard to exceed the reverse voltage specification with almost any AC voltage.

So John, on the two FasTrack lighted bumpers I just repaired per an old thread of yours, I should have put a diode in?  Why didn’t Lionel? I just see a resistor in line with track power. 

Nobody can explain why shortcuts are taken with various circuits.  My personal experience was that I had several LED's croak in TMCC locomotives with 470 ohm resistors, which should keep the average power to the LED well below it's 20ma rating.  After adding the diodes to my upgrades, I haven't lost an LED since.