# Horn buttons - 81251-50 vs 6-5906



## ChopperCharles (Jan 3, 2012)

I have two Lionel horn buttons. One is an 8251-50, bright red. the other is a 6-5906. What's the difference? The 8251 has very small gauge wires, connects to both base and power terminals on the transformer, and has no problem getting my 703 air tender to whistle. The 6-5906 on the other hand, can barely make it whistle even at full throttle. 

What's the difference in these buttons, and under what circumstances are they used for? I'm guessing the 6-5906 is only used to activate digital sounds? But internally I'd like to know what makes them so different.

Charles.


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## BigAl56 (Dec 14, 2011)

I have Lionel sound buttons in Red and Black. I don't think there's any difference other than the color.


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## ChopperCharles (Jan 3, 2012)

There's definitely a difference. The red one will operate the whistle, the black one will not.

Charles.


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## gunrunnerjohn (Nov 10, 2010)

Try reversing the connections to the black box, it's probably trying to run a bell and is reverse polarity.


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## ChopperCharles (Jan 3, 2012)

Tried that. In one direction it will barely operate the whistle. In the other it won't operate it at all. The buttons are different, and I'd like to know how...

Charles.


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## gunrunnerjohn (Nov 10, 2010)

Well, unless you bought then new, the diode in one of them may be bad. 

This was discussed in detail over at OGR: http://ogrforum.ogaugerr.com/displayForumTopic/content/2415514336840871


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## ChopperCharles (Jan 3, 2012)

So... the red button has a resistor in it too then? That thread mentions a 167 (no idea what that is), but doesn't specifically mention the 8251-50.

Charles.


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## gunrunnerjohn (Nov 10, 2010)

The #167 is actually a pretty sophisticated thing with a voltage boost for old PW whistle tenders. I think I still have one somewhere in my stuff.

Here's a comprehensive page on the Lionel #167 Whistle Control


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## ChopperCharles (Jan 3, 2012)

I'm not really concerned with the 167. I guess I'll just have to take these apart to find out what's inside. Easy enough for the black one, but the red one (that works) has no screws, it's all glued together. 

Charles.


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## gunrunnerjohn (Nov 10, 2010)

Hammer?


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## ChopperCharles (Jan 3, 2012)

Okay, so there's something different about the red box. I cannot get it open without destroying it (just tried). However, it CANNOT be the same as the black box.

It has two wires that attach to the transformer base and voltage output. Neither of these wires are marked, they're both the same color. It has a red and a white wire coming out the other side, which goes to a lock-on. It does not matter which way you connect the two black wires to the transformer, the red will always go to the center rail and the white to the outside rail. Swapping the base and power leads on the transformer does not change which rail is the hot one. 

There is something else going on inside of the red whistle control button.

Charles.


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## gunrunnerjohn (Nov 10, 2010)

That actually makes perfect sense, did you look at my home-made box? It does the same thing, the connections to the transformer are not significant, since the DC offset is generated in the box. However, if you connect a box in series with one transformer lead, the polarity of the wires IS significant, since you have to get the diode inside the box oriented in the correct direction to generate a positive DC voltage offset on the center rail.

One thing about the 6-5906 model, it might need a load to operate an electronic whistle properly.


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## ChopperCharles (Jan 3, 2012)

Photos of buttons: 


















Charles.


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## gunrunnerjohn (Nov 10, 2010)

Yep, my previous comments still apply.


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## ChopperCharles (Jan 3, 2012)

Just tested, load made no difference. The black button is still much weaker at blowing the horn. It takes much longer to spin up and it doesn't spin nearly as fast. At half throttle it takes a good 15 seconds to spin up enough to make a whistle noise. Yes. Fifteen seconds. I counted. At less than half throttle it never spins fast enough to make the whistle.

However, the red button takes less than a second to make the whistle, even at 1/4 throttle. 

The black button is obviously working, and no doubt if it was a railsounds tender instead of a whistle tender it would work fine. My question is WHY. What is different?

Charles.


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## gunrunnerjohn (Nov 10, 2010)

Obviously, they've done something different in the button, I don't currently have either of those, that's why I built my box. I don't do much conventional, but when it comes up, I need a horn and bell control.


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## T-Man (May 16, 2008)

Here is the 8251, the 5906 ? well it's your turn to open er up!











5906 thread

What John says about a load, rings a bell , You may need a lighted car to add to the track.


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## ChopperCharles (Jan 3, 2012)

The inside of the black button is 7 diodes, nothing more. What is all that inside the 8251?

Charles.


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## T-Man (May 16, 2008)

Aside from the diodes, that glass tube has a bimetallic strip that cools and heats. To make a switch.

The big question now, is what whistle are you using? The 8251 is designed for a old relay. The 5906 is used for electronic whistles.


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## ChopperCharles (Jan 3, 2012)

I listed that in my first post 

703 air tender, no relay. A little circuit board and a can motor driving a plastic fan into a big plastic air chamber.

Charles.


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## ChopperCharles (Jan 3, 2012)

On the bottom is says "K-Line K3501-M002"

Charles.


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## T-Man (May 16, 2008)

The best description is at Olsen. Here is a TJ link.

The 8251 may work better because it starts with a higher DC voltage. The after the strip heats the voltage lowers. This is for old relays that need the extra umph to start the motor and the lower to voltage to keep it running.

There is a lot info here it is just everywhere. I keep finding more. The Olsen page explains the theory.

THE Buttons were big in the 70's since most transformers were small with no buttons, I have a few tenders with whistles but haven't done much except collect information on all the whistle controllers during the years.


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## BigAl56 (Dec 14, 2011)

I have used both these buttons to mixed results. The wire is of too small a gage to carry enough current to the whistle motor. If you must use them replace the wire with a heavier gage. Try rewiring them with lamp cord.

Bottom line is throw them both away and purchase a modern transformer with both whistle and horn buttons. Problem solved.


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## ChopperCharles (Jan 3, 2012)

Not going to get rid of my vintage transformer, that's not an option, so I'm stuck with the buttons. I'll find a way to open this case and replace the wires with lamp cord or something. Button only cost me $10, mad cheaper than a new transformer. 

Charles.


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## T-Man (May 16, 2008)

With electronic whistles, I would not suggest any older whistle controller. If the button works use it, if it doesn't work to your satifaction don't. My recommendation and from other members is to build one. I collect them mostly for information and show.


The 167 whistle controller. This may explain more though it has no modern diodes.


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## ChopperCharles (Jan 3, 2012)

I took the red button (8251-50) apart, and it looks different than the photos above. There is no glass resistor thingy, and the button has two stages. I don't really understand what this is doing, but I can write the schematic at least.










Charles.


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## ChopperCharles (Jan 3, 2012)

In testing, when the button is pressed half way, the whistle immediately spins up and makes a low whistle sound. When I press it in all the way, more power is delivered to the whistle - the locomoive lights glow brighter and the whistle intensity increases. Basically, the red whistle button allows me to modulate teh whistle, which makes it sound much more realistic. 

Charles.


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## tjcruiser (Jan 10, 2010)

I'll defer to the electronics gurus for the detailed description, but what I think is happening is that the half-pressed position is sending a higher DC voltage to initially trip (toggle on) the whistle relay. Once that's activated, you don't need as much power to hold it on. So, the full pressed position backs off on the DC signal, leaving a bit more AC juice available for the AC powered light, loco motor, and whistle motor.


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## ChopperCharles (Jan 3, 2012)

At any rate, this sounds much nicer than the black button - and works much nicer. I'm guessing it works better because there are fewer diodes in the circuit allowign more power to get to the whistle tender. It sounds better by nature of being able to modulate the whistle. Which granted, would be useless for an electronic whistle, but works VERY well on the air whistle tenders.

Charles.


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## gunrunnerjohn (Nov 10, 2010)

TJ is right, interesting circuit.

If you really want to modulate the whistle, get a Lionel Legacy system.


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## ChopperCharles (Jan 3, 2012)

The biggest thing I see with this though, is there's not an easy way to duplicate the two-stage on, on, off/on momentary pushbutton action with readily available electronics. But it's nice to know the circuit is so simple, if it does burn out it will be a cinch to repair. It's just a bit of a ***** to open the red box up, as it's all glued together.

Charles.


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## gunrunnerjohn (Nov 10, 2010)

Well, it is possible to duplicate it, but why bother, the low-tech solution works.  If I wanted to do this with electronics, I'd use a relay with a time delay to switch it to the second stage. Of course, I'd also do the DC in a different manner. Truthfully, there's no demand to "improve" the whistle button for conventional running, probably why it hasn't been done.


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## ChopperCharles (Jan 3, 2012)

Well, obviously there WAS reason to improve the whistle button, because it's gone through several different designs over the years. The red box 8251-50 is the best one for can motor-driven air whistles. Sound Activation button works for electronic sounds, but not well for the air whistles. Since the homebrew button is directly based off of the sound activation button (just a bunch of diodes), it's not going to work well for air whistles either. And the 8251-50 is the only button so far that gives a nice two-tone modulation to the air whistle. 

No idea how either of these work for the older (postwar through 70's) whistles or horns, but for modern air whistles, it works great. All it needs is the wiring replaced with something a little more heavy-duty.

Charles.


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## ChopperCharles (Jan 3, 2012)

I've created a video to show the difference between the two buttons: http://www.youtube.com/watch?v=wsneztrGy6E&feature=youtu.be

Charles.


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## gunrunnerjohn (Nov 10, 2010)

Great video, that's a perfect way to demonstrate that. Do you know you can embed the videos here like this?


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## tjcruiser (Jan 10, 2010)

Interesting demo video, Charles ... nicely done.

TJ


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## T-Man (May 16, 2008)

I guess if it works go with it. 

I have a question , I always thought the button was just to activate the whistle not run it. It should be on a track for that power. That is my reason for the 5906 running poorly. The 8251 does run at a higher DC volatge. Can you get a meter reading on them?


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## ChopperCharles (Jan 3, 2012)

It activates a digital sound, postwar horn, or a bell, but for the MODERN air whistle it powers the motor. I believe the older whistles had a relay just like the battery powered horns did. I had the thing wired up as if on a track, I had the alligator clips attached directly to the wheels and to the center pickup. 

Charles.


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## gunrunnerjohn (Nov 10, 2010)

Well, the AC really runs the whistle after rectification. Here's the circuit for many modern Lionel whistle tenders.


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## ChopperCharles (Jan 3, 2012)

That's different than my board. Mine has three diodes, two resistors, a transistor, two big electrolytic capacitors, and a voltage regulator. Board K-031.

Charles.


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## T-Man (May 16, 2008)

I got my 8632 tender out and behold. It must be the same.


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## ChopperCharles (Jan 3, 2012)

Interesting note: The half-press of the red button does slow the locomotive down. However, the full press does not appreciably affect the speed of the train. 

Charles.


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## T-Man (May 16, 2008)

*48051 controller*

I got out the 8632 set to try the tender, but first I took a peek at the whistle button on the 58051 controller.

Remove three rubber pads to expose the 4 screws and you are in.










The button is above the just above the capacitors a 220 and 470uf. A 1N4002 diode on the right and few smaller ones to the left. The knob was no removable and the potentiometer was fixed to the cover.
Too much work to get a good picture of the insides.











The circuit was more complicated than I thought it would be.


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## T-Man (May 16, 2008)

This is a test of the whistle tender. A DC motor mechanical whistle with electronic apllication. It does not have the classis two tone pitch as in the older whistles.


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## ChopperCharles (Jan 3, 2012)

One question about the 5906... why so many diodes? Wouldn't one or two do the job just as well as 7?

Charles.


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## gunrunnerjohn (Nov 10, 2010)

ChopperCharles said:


> One question about the 5906... why so many diodes? Wouldn't one or two do the job just as well as 7?
> 
> Charles.


If it would, it would be a 6-5906, right?


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## ChopperCharles (Jan 3, 2012)

Interesting aside - The 5906 button has seven diodes in a loop, with the NC switch (and input/output) bridging across one of the diodes in the series. That is what is necessary to activate railsounds. I've tried it with less diodes, and the fewer diodes the less the train slows, but also the longer it takes for the sound to react to the button press. More diodes equals less delay, but more diodes also equals slower train, so it's a trade-off.

During my testing however, I did make the observation that a whistle tender, like in the 703 Reading tender I have (or say a Hogwarts tender), requires only ONE diode to activate itself. The more diodes you put in series, the slower the tender spins. 

Charles.


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## gunrunnerjohn (Nov 10, 2010)

I'd have to see how the diodes are actually wired in the switch to figure out what they're doing. Old PW transformers had what amounts to one diode, the selenium rectifier disk. Modern transformers like the CW-80 put out about 2.5 volts DC offset which works fine for modern whistles.


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## ChopperCharles (Jan 3, 2012)

Here you go:










Charles.


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## ChopperCharles (Jan 3, 2012)

To activate the motor-driven whistle tender, the only diode necessary is the one between the switch. The other six can be omitted. This will not, however, activate railsounds. 

Charles.


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## T-Man (May 16, 2008)

A diode drops the voltage by .7 volts. Track voltage for postwar operation is around 8 volts on average. The diodes reduce this to about 4 volts dc which is needed to activate the relay. An Explanation here is not my strong point I go with what works. Deviation will normally precede disaster.

I am not sure what you are trying to do. Just use the button.

The less diodes you use the more power is taken off the track and the train slows more.


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## ChopperCharles (Jan 3, 2012)

T-man, that's not my experience at all. The MORE diodes I use, the slower the train goes.

What I'm trying to do is build my own buttons that will activate both railsounds AND modern motor-driven whistle tenders (like, since the 90's). There are no relays, they're DC can motors driven by a little sensor board with a transistor and a couple of caps on it. 

Problem 1: 6-5906 button works for railsounds, but not for modern whistle tender.
Problem 2: 8251-50 Whistle control button works for modern whistle tender, but not (reliably) for railsounds. The wires are also extremely thin gauge and the diodes inside are only 1 amp. So they're prone to burning up. 

My original solution was to use two 6-5906 buttons and one 8251-50, but at $25 a button that's pricey, and there is still no solution for the cheesy wiring and diode rectification in the 8251-50. So it is cheaper cheaper to buy the diodes and some pushbuttons from digikey and build my own. 

Now, I do believe the 8251-50 was made to activate older whistles as well, which is why the wiring inside is pretty funky, with a two-stage switch that would be difficult to reproduce. However, a modern whistle tender only needs to sense a very slight DC offset to activate, and one single diode in the power line does that nicely.

Charles.


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## gunrunnerjohn (Nov 10, 2010)

I think T-Man means the less diodes in the circuit when the horn blows. That appears to be a different way of doing what the circuit I used does. It keeps full voltage on the track, but puts a DC offset onto the track that is the value of the difference in the drop across one diode vs. six diodes. Interesting way to go.


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## ChopperCharles (Jan 3, 2012)

Well, thanks John. Now I know WHY it works. Also, it's not anything special I did, that's the schematic from the 6-5906 Lionel Sound Activation button. I might wire up your solution too and see which I like better, I've got a metric assload of these diodes 

Charles.


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## gunrunnerjohn (Nov 10, 2010)

I have a drawer with several hundred 3A diodes, and about 50 of the 6A ones. For this application, 3A diodes normally work, as they only carry half the current of the total load.


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## eljefe (Jun 11, 2011)

Charles--I recently found a 8251 but am not really happy with its performance. Did you ever find or build a good solution?

I'm interested in some kind of control for a train display where kids can operate the horn/ whistle/ bell without access to the transformer.


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## eljefe (Jun 11, 2011)

Hmmm, guess no one has any suggestions on my question on alternatives...


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## gunrunnerjohn (Nov 10, 2010)

I rolled my own with some diodes and a couple of pushbutton switches.


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## larry g (Oct 8, 2012)

*no screws?*

Double check for stickers on the bottom. I thought mine was glued, but there were stickers covering the screws.


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