Adding LED lights to a PS2 Engine

What sized resistor did you use? too low a voltage and the LED won't light. maybe like 300 to 500 ohms?

What exact bulb/LED was used? Built in resistor for 12 volts?

Did you get the polarity correct?

https://ogrforum.ogaugerr.com/...90#21843891958004190

I've put tons of LED's in PS/2 stuff, a 220 ohm resistor in series with the LED work for standard white LED's.  If you are powering colored LED's from the incandescent outputs, a 330 ohm resistor is good.

Hello!  It's been awhile but I just sat down to try and finish wiring LED lights in this engine but I've run into a couple problems that have me scratching my head.  I bought the 220 ohm resistor to add to the LED but have no idea how to hook it up to the light. (That sounds stupid but this is new territory for me.)  After I figure that out, I some how need to wire the headlight and added strobe light to the directional control for the DCS engine. (When I have it in forward, the strobe and headlight come on, when I throw it in reverse they go out, etc.)  I think I just need to tie into the two wires that connect to the bayonet base of the bulb but am not really sure, I tried that and now can't seem to pin-point a power and a ground from the two.  I traced it back to a little two-pin plug with a blue and a purple wire to it.  I would think that they would be a power and a ground but I'm not sure.  After I get this figured out, I would like to add marker lights to this E8 as well and somehow need to pick up power for them too.  This sounded like a much easier project in my head.

Thanks,

I also order 9-12v 2mm tower LEDs for the markers which I'm hoping was the right kind.

you have  to watch with mth engines when you test voltages and are unsure of the ground . if you measure to the wrong ground you can blow the boards ! metal chassis ground Is not the ground used! PV is the voltage created for smoke n lights but not related to actual ground, purple wire is where pv (positive voltage) is created!

as far as the led your talking about the 220 ohm is in series with the (led) you could even run your led from track voltage with the 220 ohm resister in series!

Measuring it won't blow the boards, it's when you try to use it.

Alan Mancus posted:

as far as the led your talking about the 220 ohm is in series with the (led) you could even run your led from track voltage with the 220 ohm resister in series!

Running a standard white LED from track voltage with 220 ohms in series is running it at about twice it's rated current, the LED will NOT last long with that configuration.  If you assume half-wave RMS value for the voltage applied, for 18VAC, that's 12.73 RMS volts.  Assuming the white LED operates at around 3 volts, that gives you 41ma RMS to the LED.  Next, let's talk about the reverse voltage specification of the LED component, it's typically around 5V.  Peak voltage for a half-wave 18V is 12.7 volts, far in excess of the rating of the LED.

If you want to run LED's from track voltage I recommend 470 ohms (or larger) and a diode to protect against reverse voltage.  If you have two LED's, you can wire them back to back with the polarities reversed, they protect each other and you only need one resistor and no diode.

Okay, so if I'm understanding this right, there is no easy way to power the LEDS in such a way that they turn on when the engine starts up via the DCS remote and go out when you put the engine in reverse.  If I want LEDs to function all the time, I would need to wire them using the appropriate resistor combination to track power.  I was reading and when I bought these lights how ever long ago, they were rated for 9-18v 

Actually, that's not really true.

You can use plain LED's, and NOT the stuff you purchased that's rated for 9-18V.  Let's take your example of one LED headlight and two marker lights.

Wire the two markers in series with a 220 ohm resistor in the circuit and wire the one white LED with a 220 ohm resistor in the circuit.  Wire these two assemblies in parallel across the PS/2 headlight output.  Note that the purple lead is positive.  Also, the resistor can go anywhere in the circuit in either lead.

Thank you for your help!  This is very new territory for me and your help is so very much appreciated.  In the drawing you have indicated that it all circles back and goes to what I'm assuming is a ground (-) wire?  This isn't the chassis ground right, this (-) would be the blue wire?

Correct, NOTHING is chassis ground in a PS/2 or PS/3 system.  The two wires are the headlight wires.

PS-2 uses the purple wire (Normally) as the + DC voltage source for all lights, couplers and smoke heater.  The return line which is the various color wires like blue for headlight or green for reverse light is the return to -DC via the control fet on the PS-2 board.  Effective voltage is about 6V.  So if replacing a HL with a LED use a resistor to drop the 6V to the appropriate level for proper current flow as John showed you.   G

Okay, thanks guys!  So the LEDs I need to get need to be in the 3-5v range?

Well kind of.  I bought a 50 pack of Warm white LED's and the input voltage range was from 3.2 to 3.8 volts with an amperage draw of 20 to 30mA. Using a simple LED resistance calculator, I picked a 3.5 volts as safe average input voltage to the LED, and picked 6.0 volts as the supply voltage. I then entered my desired mA rating and the calculator selects the closest size of resistor needed to deliver the proper voltage & amperage to your led.

This is the calculator that I used: http://ledcalc.com/

White LED's have an operating voltage in the 3.0-3.5V range.  I assume they're 3.0 volts and work from there.  For PS/2 lighting, I use a 220 ohm resistor, works well and I've never had a problem with the LED's.

I thought this was answered pretty fully with the diagram?

It is, I'm sorry, just checking to make sure! 

Horrors, you doubt me?

Not on purpose, I swear

Just kidding Landon, absolutely no reason not to make sure of the facts before cooking something.