Headlight wired with class lights ?

An expert will no doubt weigh in, but I notice that the last post in a thread you contributed to, https://ogrforum.com/...#157970176377529874, states (per @gunrunnerjohn) that a PS2 lighting circuit can handle multiple LEDs even if an earlier post says no more than 3 incandescent bulbs. So installing an LED headlight on the classification lights circuit might work - I don’t think PS3 differs in this respect but I’ll be corrected if I am wrong.

@Hancock52 posted:

An expert will no doubt weigh in, but I notice that the last post in a thread you contributed to, https://ogrforum.com/...#157970176377529874, states (per @gunrunnerjohn) that a PS2 lighting circuit can handle multiple LEDs even if an earlier post says no more than 3 incandescent bulbs. So installing an LED headlight on the classification lights circuit might work - I don’t think PS3 differs in this respect but I’ll be corrected if I am wrong.

Just don't have the cash to throw at a new board .  Always makes me sweat when I throw the TEST switch.

Since the ps3 already has LEDs I wondered if there was a different load maximum on the individual circuits. It might seem silly but I've only added LEDs to ps2 boards in the manner GRJ has instructed.

Not to worry Hancock , I'll not be correcting you. I appreciate your reply , and I think you are right. 

@Hancock52 posted:

An expert will no doubt weigh in, but I notice that the last post in a thread you contributed to, https://ogrforum.com/...#157970176377529874, states (per @gunrunnerjohn) that a PS2 lighting circuit can handle multiple LEDs even if an earlier post says no more than 3 incandescent bulbs. So installing an LED headlight on the classification lights circuit might work - I don’t think PS3 differs in this respect but I’ll be corrected if I am wrong.

You'd be wrong.   PS/3 has totally different lighting circuitry, and in no way rivals the power output of the PS/2 boards.  You can connect several LED's across one lighting output, but certainly you can't connect anything like the loads that you can on a PS/2 board.

Truthfully, the limit on the PS/2 boards is probably way more than three bulbs.  I know I've connected four to the headlight output several times with no issues in steam, dual headlights, firebox, cab light.  The FET used is rated at more than am amp continuous current, 240ma is loafing for it.  If you had enough current draw from multiple lighting circuits on the PS/2 board, you might start taxing the power supply.

John , would you solder the headllight wires to the classification light's wires on the ps3. 🤔

@Dallas Joseph posted:

I know the headlight won't go out when the engine is put in reverse but AT LEAST it won't come on with track power if this would work.

For steam, the headlight is on in either direction.

@Dallas Joseph posted:

John , would you solder the headllight wires to the classification light's wires on the ps3. 🤔

The class lights are a different voltage, so you're likely to have conflict issues with only the class lights lit, or only the headlight lit.  In order to make this work, I think you may need a load balancing resistor in the lower voltage LED circuit.  I don't remember if the class lights are wired in series or parallel, don't have one to look at right now.  If they're series, the headlight would light and the class lights would not.  If they're parallel, the class lights would light and the headlight would not.

@gunrunnerjohn posted:

For steam, the headlight is on in either direction.

The class lights are a different voltage, so you're likely to have conflict issues with only the class lights lit, or only the headlight lit.  In order to make this work, I think you may need a load balancing resistor in the lower voltage LED circuit.  I don't remember if the class lights are wired in series or parallel, don't have one to look at right now.  If they're series, the headlight would light and the class lights would not.  If they're parallel, the class lights would light and the headlight would not.

I'll open it up .   Pretty sure I remember the class lights being in series.   Thanks John.

If the class lights are in series, then the headlight would need a balancing resistor, figure around 100 ohms, in series with one of the leads.  That would allow the two series class lights to have enough voltage to illuminate.

Has it been established that changing the driver chip to the headlight LED is impractical? I'd think it could be a generic inexpensive 5V digital logic buffer chip that drives multiple LEDs vs. the discrete FETs in the PS2.

Stan, they drive the LED's through a resistor network directly from the microprocessor.  I have a diesel one with the same issue here.

OTOH, since this is a steamer, I don't know why we don't just swap the boiler board, they're not that expensive.

@gunrunnerjohn posted:

If the class lights are in series, then the headlight would need a balancing resistor, figure around 100 ohms, in series with one of the leads.  That would allow the two series class lights to have enough voltage to illuminate.

Would some 150 ohm resistors work ?

Yep, you just need one.

@gunrunnerjohn posted:

Stan, they drive the LED's through a resistor network directly from the microprocessor.  I have a diesel one with the same issue here.

OTOH, since this is a steamer, I don't know why we don't just swap the boiler board, they're not that expensive.

Is the boiler board just a plug and go ?  What does MTH charge roughly for the replacement ?

Well, the MSRP is $60, but they're out of stock anyway.

@gunrunnerjohn posted:

Well, the MSRP is $60, but they're out of stock anyway.

The 150 ohm resistor is paid for already ,John

Just throw the resistor and headlight positive wire on the positive wire to the class lights and run the second wire to the class lights ?  🤔

Yep, the headlight with the resistor in series is wired in parallel with the class lights.

@gunrunnerjohn posted:

Stan, they drive the LED's through a resistor network directly from the microprocessor.

That figures.  Oh well, I guess Rule 17 headlight dimming is not THAT cool! 

But if driven directly by a 3V or even 5V microprocessor, it's curious that the Classification Light LEDs can be in series.  Aren't they typically green?  Two green LEDs in series I'd think would push the voltage swing of a standard (without external buffer) microprocessor output pin. 

@gunrunnerjohn posted:

Yep, the headlight with the resistor in series is wired in parallel with the class lights.

GRJ ,I soldered the 150 ohm resistor and headlight  LED positive to the positive wire going to the series connected class lights.

I then soldered the headlight LED ground to the ground coming back from the class lights.

All lights worked.     The headlight wasn't the brightest  bulb in the bunch !!! 

If I replaced the 150 ohm with a 220 ohm resistor would the headlight be brighter ?     

No, replace the resistor with a 50 ohm and see what it looks like.

@gunrunnerjohn posted:

No, replace the resistor with a 50 ohm and see what it looks like.

I'll have to order some......150 ohm is the lowest I have.

Thanks for your help John............and Stan 2004 and Hancock52.

@Dallas Joseph posted:

I'll have to order some......150 ohm is the lowest I have.

Thanks for your help John............and Stan 2004 and Hancock52.

Three 150 ohm in parallel, equals 50 ohm.

@RoyBoy posted:

Three 150 ohm in parallel, equals 50 ohm.

Roy......this is a new chapter on resistors for me.    Thank you.

Right now I have the 150 ohm on the positive wire to the LED headlight in parallel to the class lights in series.

Do I just put three of these in a row on that positive wire now ? 🤔

Parallel means parallel.

@gunrunnerjohn posted:

Parallel means parallel.

Tried 3 in parallel , then 2 in parallel .  The headlight was brighter.   The class lights became dim.

Went back to 1 of the 150 ohms.  The headlight was bright enough and only came on when the steamer started up .  The class lights were bright again.

Thanks for your patience guys.

@gunrunnerjohn posted:

Well, the MSRP is $60, but they're out of stock anyway.

It looks like I'll have to be patient and wait for the boiler board to become available IF it does.

All that happens is it is tripping the Z1000 brick now.

$60 is worth it if I want to have the Allegheny back in operation....

I was able to find a boiler board in my parts drawer but it wasn't exactly the same but it made the lights work , the smoke unit, the tender coupler and after I did the horn and three taps to get it out of neutral I saw the light on the tender functioning for reverse and brighten on the second tap on the direction button ...........but no motor movement.   The motors both worked with a nine volt.     

I did this in conventional  AND on the full DCS / TIU/ REMOTE.   No change.

Until next time John , thank you.