Pullmor / Post War speed-limiting

Could you not just limit the voltage to the track when the kids are running the trains? Something between the AC output of the transformer and the track lockon, so that full throttle isn't, really.

@D500 posted:

Could you not just limit the voltage to the track ... so that full throttle isn't, really.

that's probably simpler. and is still along the lines of what I'm hunting for.

I am searching for an AC voltage regulator/limiter on the interwebz and I'm having difficulty finding an AC-to-AC unit that will accept the 5~24 volts at 6~10 amps. Most that I'm finding are DC output and/or only accept lower voltages and amperages.

@woodsyT posted:

I have a few nephews/nieces, 6~10 years old, and just like my grandfather before me - I was surprised by their lack of ability or willingness to control the speed of the choo-choos and keep from sending them at rocket speeds and sometimes off the track. Their lack of 'control' isn't only mischief/malice, but also attributable to a lack of motor skill and lack of experience/familiarity. I think I want to set up an engine or two for them that only go 'so' fast and won't fly off the track, till they can mature and learn a bit. I have a couple of postwar 2065s that they like for the green LED registration lights on the front and red LED tender tail-lights that I've added.

Anyhow, I'm thinking that if I reduce the voltage to the brushes without reducing the motor coil voltage I can keep them from 'racing' so fast. Whaddya think? I searched the forum a lil' bit and didn't find anything for conventional postwar motors except maybe a string of diodes or rheostat but how much additional amperage am I 'adding' to the motor to do that? Is there some small switching regulator/voltage limiting thingy that can deal with the amp draw of the pullmor motor?

ideas/suggestions/laughter/eye rolls are welcomed?

Well, assuming you are operating in conventional mode, you could go really old-school and use a method Lionel proposed years ago: at critical points on the layout (basically, any sharp curves), you can provide an automatic throttle-back by isolating a section of the track's center rail approaching, within, and exiting the curve, using insulating pins at each end of the center rail, and connect power to that isolated section from the rest of the loop through a low-value, high-power resistor (a slider or high-power pot would be ideal for experimentation, but if you can figure out the correct value -- I'd guess something about 2-5 ohms and 10 watts -- you can use cheaper fixed resistors). This will drop the voltage available to any locomotive within the "danger zone", automatically reducing its speed while it's in the section. If desired, you can at other times bypass the speed limitation by bridging the resistor(s) with an SPST switch or jumper clips.

Give them a smaller transformer

@woodsyT,

If you're presently using a traditional transformer how about adding a variac to dial down your input voltage coming from the wall to your transformer?:

As you rotate its knob to something less than 120VAC and keep going down the input voltage to your transformer will go down, and hence so will your transformer's output voltage.

Set it where you'd like to to be and then hide it from the kids so that they can't play with the knob after you've set it.

However, be aware that this device can also exceed 120 VAC, in fact in can go up to 130 VAC, if you turn it up instead of down.

Use it wisely though and you'll be fine.

This one is about 50 bucks at Amazon.

Mike

@Bill DeBrooke posted:

Give them a smaller transformer

Easiest, fastest solution right here!

RW Transformers are really cheap.

I wonder if a dimmer switch can be installed inline between the outlet and your transformer to reduce the input and hence the out put voltage?

@H1000 posted:

Easiest, fastest solution right here!

I wonder if a dimmer switch can be installed inline between the outlet and your transformer to reduce the input and hence the out put voltage?

Two points about dimmers:

1. Unfortunately a traditional wall-mounted dimmer switch is meant for lamps, and for the most part only incandescent lamps.   Not LED lamps, not fluorescent tubes, not motors, and not transformers.
2. They reduce AC voltage in the same way that modern toy transformers do, by switching off a a greater and greater portion of the AC waveform as you turn their knob downward.   You get the clipped waveform that so many people in our hobby have a problem with.  Is it really a problem here?  Probably not because @woodsyT is using them with traditional toys and not precison scale machines.

A variac doesn't have these limitations though and is likely to be much safer because it's designed to work with motors and transformers.

Mike

Mike those are good points but a wall dimmer is exactly what my dad used to speed control our zw many years ago so that we wouldn't turn our trains into rockets. It worked well, and no damage done to anything.

A quick Amazon search revealed this handy guy: https://www.amazon.com/DEWENWI...ps%2C374&sr=8-12

@H1000 posted:

Easiest, fastest solution right here!

RW Transformers are really cheap.

I wonder if a dimmer switch can be installed inline between the outlet and your transformer to reduce the input and hence the out put voltage?

Even easier: add a small-value power resistor in series between the transformer and track, if all you want is a general limitation of speed. Even easier than that: just stick a block on the transformer that limits max throttle position (3M makes removable wall anchors perfect for this).

@H1000 posted:

Mike those are good points but a wall dimmer is exactly what my dad used to speed control our zw many years ago so that we wouldn't turn our trains into rockets. It worked well, and no damage done to anything.I hear ya, but ...

As far as you could tell.  But just because your house didn't burn down doesn't mean that everyone's won't.  The law of averages tends to catch up over time.

Just to be safe read the instructions that come with the standard dimmer you're considering before attempting this to see if it will accept motors or transformers.  Some will, but I think you'll find that to get that capability in a dimmer requires a special one and then you'll be at or near the $50 point anyway.

Mike

@Steve Tyler posted:

Even easier: add a small-value power resistor in series between the transformer and track, if all you want is a general limitation of speed. Even easier than that: just stick a block on the transformer that limits max throttle position (3M makes removable wall anchors perfect for this).

The 3m block won't last long. I'd bet kids would figure out how to remove that.

The resistor better be pretty big, it's going to have a hefty load and it's going to get hot.

@Mellow Hudson Mike posted:

As far as you could tell.  But just because your house didn't burn down doesn't mean that everyone's won't.  The law of averages tends to catch up over time.

Just to be safe read the instructions that come with the standard dimmer you're considering before attempting this to see if it will accept motors or transformers.

Mike

Dimmers all pretty much work the same, they modify the sine wave to reduce the overall effective volts to the load.

Better be careful running postwar motors with a new ZW-L because it does exactly that, and those postwar motors were never designed with modified sine wave in mind. (It'll be fine).

I wouldn't use dimmers with newer electronic Transformers but older conventional / mechanical (postwar) Transformers are probably going to be okay.

GAH! (slaps forehead)

I feel like a dope I have a 1033 transformer on the shelf! Posts B-U only give about 10~11 volts. And I am still building the table, but have the ability to add or swap transformers fairly easily.

Bank the curves !

@woodsyT posted:

GAH! (slaps forehead)

I feel like a dope I have a 1033 transformer on the shelf! Posts B-U only give about 10~11 volts. And I am still building the table, but have the ability to add or swap transformers fairly easily.

Yep! That's the answer!

Now your new problem is explaining to the kids what happened to the "faster" transformer.

@woodsyT your instincts are spot-on:

"The speed of the toy motor can be reduced by bridging a 4-ohm resistor across the brushes of the motor but not across the field.  This resistor acts as a shunt to by-pass some of the current around the armature thus causing the armature to get less current and the field more current.  In this way a definite speed reduction can be obtained.  However, this scheme will not work with all motors equally well and some experimentation may be necessary to determine the exact value of the resistor.  It should not be less than 4 ohms and should not be more than 10."   --W. K. Walthers, Handbook for Model Railroaders, Kalmbach Publishing Co., 1946.

The speed of a series motor is very sensitive to load.  Just switching to the transformer's lower voltage range (with 11 volts max on the rails) will limit top speed, but it may not give you enough voltage to start a heavy train.

Alternately, you could just break the piggy bank and buy a Lionel 773   Ironically it's probably the most kid-proof of all postwar steam locos!

My NRHS chapter has LGB trains for the kiddies to play with at shows; they limit the speed by screwing small wooden blocks to the transformer so the kiddies can only go so fast, and the blocks won't fall off like the 3M stickies might... 

Mitch

@Ted S posted:

@woodsyT your instincts are spot-on:

"The speed of the toy motor can be reduced by bridging a 4-ohm resistor across the brushes of the motor but not across the field. ...

...Alternately, you could just break the piggy bank and buy a Lionel 773   Ironically it's probably the most kid-proof of all postwar steam locos!

Right on!

I was thinking that keeping the coil with a higher voltage would provide better start/stop/torque behavior and getting the armature run a little bit lower would keep speeds down enough to prevent 'ejection from table orbit'. I learned a whole lot about this stuff 20~30 years ago & I haven't practiced it all that much, so my memory fades...

- and if you know anyone getting rid of a few 773s, please call me first 😉👍😂

@M. Mitchell Marmel posted:

My NRHS chapter has LGB trains for the kiddies to play with at shows; they limit the speed by screwing small wooden blocks to the transformer so the kiddies can only go so fast, and the blocks won't fall off like the 3M stickies might... 

Great minds, and all . . .

Yeah, my initial thought was to just screw a stop into the throttle range (I did an internal version when one throttle on my LW kept exceeding the max setting and dropping the wiper off the end of the coil, due to a broken internal stop), but discarded that idea in favor of a more temporary and removeable alternative, since I suspect with even minimum supervision you'd be able to thwart any juvenile attempt to remove a temporary stop. IF you still want something more substantial, you might be able to carefully drill and tap a hole in the transformer's face, which would allow a stop to be easily installed and removed at need, yet not seriously mar the transformer in the process. Good luck!

or you can go old school and use a Lionel #95 reostat hidden away to limit voltage to the trains. I use them for downhill blocks to slow my trains down

@gptom posted:

...a Lionel #95 reostat hidden away to limit voltage to the trains...

That limits current, resulting in a voltage drop, but is dependent on the load. Too much fussing.