Voltage Drop - Resistor needed for PS1 engine - HELP!

I suggest you up-grade your model to DCS command control, as well as your layout, thus you can keep the track voltage at 18-19 volts, and still effectively control train speed. Otherwise, what you are requesting really isn't possible, in my opinion.

Are you running it in conventional?

   You mention 18-19v which is a standard command's constant voltage, and 7-9v which sounds like you run it conventionally? 

I.e. if you run a command loco at speed and drop the conventional trottle from 18.5v to 16v it isnt going to slow down, the board will just feed the motor more power till it reads the rpm increase it wants to see.

In convetional you can do similar and get more smoke voltage, but changing the heat elements and opening up intake and exhaust ports on modern units helps a lot. So would using a different heat element in it either way.

Take a look at what GRJ's Super Chuffer at Henning's does for smoke units.

I think what you need to adjust your speed might be a new tach tape with more lines on it (if it uses one.)

This will trick the board into thinking the motor is turning faster than it is. E.g. chip reads 10 lines and calls that 1-rpm, so if the new tape has 15 lines the speed will read 1rpm, 1/3 of a revolution too soon. 3 turns is extra 1rpm. So anyhow, you should slow by a third going from 10 to 15 line tack tape. Tack tapes come in about any # per inch. 

You  said Protosound one, which won't work with DCS, conventional operation only. I'm confused as to if you have proto one or two? You should get more than 'puny' smoke I'd check that both resistors are good in the smoke unit. If you go the resistor route, you are going to need at least a 10 watt wire wound resistor.

OK - this is all great advice and good food for thought for other things which I'll refer on later, but my original question is getting taken wayyyy out of context.

Let me reiterate-

I have PROTO-SOUND 1.0 Big Boy and I am staying in the solely conventional world of PS1 with this. Not upgrading to PS2 / PS3 / DCS, period. I like the PS1 Big Boy sounds, so that's that. There is no tach tape involved here.

What happens is, if I get her rolling steady at slow prototypical speeds, the smoker output is almost absent because the voltage is down near 7-9 volts for that kind of speed. And since this engine goes flying when you throttle up to 17-18 volts, I want to resist the speed increase relative to the throttle/voltage increase by about 10-15%. This keeps the maxiumum speed a little bit safer whilst allowing more power to the smoke unit sooner - relative to the speed traveled.

My thinking is - simply: Leave the Big Boy completely intact as it was originally designed for PS1, but simply add a resistor between the center rail pickup and the QSI board which feeds juice to the motor. This allows the smoke unit to receive power as originally designed, and resists the board/motor from getting as much voltage as quickly, this bringing forcing me to increase the voltage to around about 9-10 volts approximately before I get her creeping along - at which point I've now got nice visible smoke.

What resistor do I need?

A friend recommended a 1 ohm 10 watt porcelain resistor for this idea.

Forget the resistor, the voltage drop varies with the load, and it'll also dissipate a lot of heat.  Instead, add some diode pairs in series with the motor to drop the voltage to the motor while retaining full voltage on the smoke unit.  Each back-to-back diode pair drops about .7 volts, you can use around 4 sets of diodes and it'll make a large difference and probably get you where you want to be.  3A or larger diodes are recommended.

If you do something like that, you have to figure out how to heat sink the resistor as it's going to get hot.  You could also run into issue with the PS1 boards, as they are rather picky about voltage signal.  The resistor may also mess up the DC offset for bell and whistle. 

My experience with my collection of PS-1 steamers is if they don't smoke well, it's time to service the smoke unit by cleaning the resistors in it and replacing the batting.  When I lived at home, my dad outlawed the use of smoke units inside because one locomotive was able to fill the room with so much smoke you'd think we were in a bar.   MTH designed the PS-1 smoke units to work really well at conventional voltages, so if it doesn't, the smoke unit needs some TLC.

gunrunnerjohn posted:

"... add some diode pairs in series with the motor to drop the voltage to the motor while retaining full voltage on the smoke unit."

There ya go!

gunrunnerjohn posted:

Forget the resistor, the voltage drop varies with the load, and it'll also dissipate a lot of heat.  Instead, add some diode pairs in series with the motor to drop the voltage to the motor while retaining full voltage on the smoke unit.  Each back-to-back diode pair drops about .7 volts, you can use around 4 sets of diodes and it'll make a large difference and probably get you where you want to be.  3A or larger diodes are recommended.

i have a bunch of 1.5 and 6 volt bulbs for class lights. Can these work?

Also, can I instead wire them between the center Rail and the board? I'm scared adding more to the motor feed will burn up the board 

Like John said,You have to reduce the voltage to the motor. Putting bulbs in will only burn them out . You might try a15 ohm 10 watt resistor in series with motor. If it was siliconed to the tender floor it might help dissipate the heat . I don't think it should hurt the board any.

As I pointed out, resistors are a bad choice.  When the load increases, say on a grade or with a heavier consist, the current to the motor increases and the voltage to the motor decreases as there is more dropped across the resistor.  This isn't the scenario you want.

gunrunnerjohn posted:

As I pointed out, resistors are a bad choice.  When the load increases, say on a grade or with a heavier consist, the current to the motor increases and the voltage to the motor decreases as there is more dropped across the resistor.  This isn't the scenario you want.

OK, I'm convinced. Which 3A diode would I need a bunch of to string together?

I see tons online with different V ratings - I see 1000V, 400V, and they're all 3A.

50V or more is fine, the voltage rating is not that significant in this application.

gunrunnerjohn posted:

50V or more is fine, the voltage rating is not that significant in this application.

Ok, I just purchased 20 of these for less than $2. Seems like a good deal. They are 1000V/3A... 

And they will not burn up my PS1 board, linked between motor and board motor feed, correct??

Well, anything's possible, but there's no reason that I can imagine they'd burn up the board.

Remember, you wire them in series with one motor lead, pairs of back to back diodes.

John,

By back to back do you mean paired with + and - together at each end?

Yes, reverse polarity for each pair, nose to tail.

I do not remember smoke output ever being an issue with the ps1 engines of the past with conventional operations.  Could it be an issue with burnt up wick needing to be replaced for more efficient smoke out put?

The question of "what size resistor" comes up so often that it needs to be restated: Resistors do not decrease voltage, they decrease current. For some reason, probably dating back to 4th grade science class, the general public thinks of a resistor when they think of voltage drop. As has been explained in this and many other threads, a fixed resistor CAN be used to lower the voltage across a particular component, such as a lamp, if the current draw is known, and the drop will be constant.  But this is the exception to the rule. It is always better to use some other method, as our friends have suggested above.

Hump Yard Mike posted:

I do not remember smoke output ever being an issue with the ps1 engines of the past with conventional operations.  Could it be an issue with burnt up wick needing to be replaced for more efficient smoke out put?

I had the same problem on my challenger.  I opened it up and added switches and a resistor to regulate the smoke.  I now have three options 1- no smoke, 2- normal lionel volume of smoke, and of course 3- regular Challenger smoke which fills the room quickly.

I use number 3 if my wife comes in and has chores for me OR if visitors are counting the rivets or logging the duplicate numbers on boxcars.

DDOTCDOT,      Although not what you intend to do...      I also have the MTH PS1 Big Boy #4012.  The smoke unit in mine smokes best around 10 - 12 volts.  I, also, took it apart and replaced the wad of packing  (wick ) in it.  It smokes very well, just about as well as when new.  Now, the difference is this.  I have converted mine over to TMCC/RS with ERR products, and when run at full 16 - 18 volts it does NOT smoke at all.  It runs very well at the 12 volts region, and pulls just as well as it does at 18 volts.  And, the smoke unit does just fine.  True, I do not have the original PS1 sounds, but the brakes and other engine sounds are there.  I can do without the station sounds and the crew talk I had with the QSI sound bites.  So, as suggested, replace the wicking in your smoke unit, it really makes a lot of improvement.  And, if you do have use of a Cab1, you can still use it in conventional mode with use of the #9 input key.  I know, there is an excellent way to have the voltage regulated to the MTH smoke unit when running TMCC, still have to open the BB up again and make the change.

Jesse   TCA

Jesse, running the PS/1 smoke unit on 5V won't yield much smoke, I'm not sure that regulator is a good idea.  For TMCC upgrades, I run the smoke unit right from the TMCC smoke output, that yields half-wave track power in command mode and full-wave track power in conventional mode.

John,      Thanks for the input.  As stated, I have not made this change, yet, so I am really glad for your comment.  So, I will now proceed with finding an available pin in the MTH tether to drive the smoke unit from the ERR board.  I do have another reason to open the tender and will look at doing this.  Without taking a look, first, I should be able to find an open pin to utilize.  I do not recall exactly where I found this schematic on the MTH smoke unit with TMCC modes.  But, I believe it was off the Forum some time back.......

Again, thanks......

Jesse

The ERR Cruise, AC, or DC Commanders all have a smoke/feature output, that's where you power the smoke unit from.

Yes.....   Just have to take a look see and determine which "open" pin I have in the ten pin tether to run signal to smoke unit from ERR board in the tender.   Should have done so when I first installed it couple years ago, but had more interest, at the time, to get the BB running under TMCC and check it out.  At the time, the smoke unit had burned out and PS1 was having problems, don't recall exactly what, right now.  Replaced the smoke unit with same as original and installed the ERR/RS about five years ago.  Time to complete the upgrade now I have more time to invest.

Jesse