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.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.

No worries, I figured you were kidding!  I appreciate your help on this and the Operating Fire House!

Okay, so I have gotten the lights to work using John's diagram (thanks again).  The next issue I have run into is figuring out a way to get a reverse light in the dummy "A-unit" and two little red marker lights. (This E8 didn't come factory with a reverse light or markers in the back)  I found a female tether end at the back of the powered A unit that is connected to the PS2 board.  Is it possible that this is set up to send power (reverse lights) to a dummy A unit if I could find a tether to fit it?  

Yes, there should be a switch (on the bottom?) of the A unit to tell it you have another unit connected (turn on those lights).

If the dummy doesn't have a tether, you can add one.  I have those tethers, drop me an email.

What's your email John?

Did you look in my profile?

Oops got it now 

I sent you an email John, I think I used the right one 

Interesting dialogue on adding LED's to a PS2 engine.  Must be a much different setup with a Williams engine.  I replaced the original headlight in an F-3 with a cool white bayonet style LED with no problem.  I assume any required resistor is built into the base of the bulb.

Yes, the resistor is in the bulb.  If you want to use a bare LED with PS/2, a 220 ohm resistor in series is the ticket.  Since the lights are driven with PWM DC voltage, you don't need a diode, the voltage never goes negative.

Hello John

Can you help me out? When you said the lights are driven with PWM DC voltage, Just what does PWM stand for and what is PWM DC voltage? I am always looking for more information. Where do suggest I find more information on how to use LEDs, like what resister do I use with LEDs on AC voltage, since it doesn't matter with DC voltage or does it. is there an area on this forum that might help?

Thanls in advance

Tim

PWM-Pulse Width Modulation

The effective voltage is 6VDC, but it's a PWM signal.  The voltage varies from 0V to a higher value, in the case of the PS/2 boards, that's around 20-22 volts max.  So, the duty cycle would be around 25-30% for an effective voltage of 6V to the bulbs.

So new problem, I've got the lights mounted in the powered A and they are working great!  I moved on to the dummy and I had power to the reverse light and started to disconnect the bayonet base.  Well I shut down the engine but forgot to pull the power to the track and I accidentally dropped the light socket on the track while it was still connected to the engine and I think I shorted something out in the board.  I went to test the reverse lights again with the light socket first and have nothing, then I tried one of the 5v LEDS and still have nothing....... You think I fried something?

Thanks,

Landon 

Yep

Grrreeeeaaaatttt. I did some testing, is it possible that I blew the 4-pin female receiver end to the tether?  When I ran a jumper wire from the board over to the lights on the dummy A, I could get them to work.

Thanks,

After some testing, I think I have isolated that this 4-pin male plug and female receiver that any bad.  I've tried finding the parts but am not having much luck.  Anyone know where I could get this replacement harness?

Rare for that to go.  I may have one.  Did you check continuity through it?  To be clear which harness, is this on the Trail A or Lead A.  Lead A has the 4 pin pcb on the truck with a internal plug?  Is that what you need?  G

Yep, I did check continuity.  It is on the lead A.  I think that is what I need.  I added a picture of what I need just for clarity.

Thanks,

You can make that cable using standard Molex connectors.

First thing is to check the solder connections on the truck mounted connector, those are easy to fix without replacing anything.  If it's the female connector in your hand, this is the replacement: Molex 0050375043, associated contacts are at the bottom of the page.

It seems like a pretty cut and dry tether, I'll do a little more checking when I get home