Can I get a quick electronics lesson?

[Anonymous]

Absolutely correct, Bob, as usual.

However, the net effect is a "relative boost," i.e. an increase relative to the power level at which the train is operating sans whistle. I am amused that the 167 whistle controller seems to follow the hypothetical design that I pondered in my post of today at 9:48:49.

If nothing else, it verifies that I am roughly 70 years behind the times, electric circuits-wise; which in turn means that I have made virtually no progress during my entire life so far.

Should you check out the link to the old stuff (167C) at Olsen's Library, check out also the #147 whistle controller. It supplied a "boost" directly to the track from a dry-cell battery. Cute.

wolverine49

[lionelsoni]

There is no boost, just a drop when the whistle is not blowing. The inductor ("choke coil") creates this drop until the button is pressed. So the voltage is always lowered, whether by the inductor or by the rectifier. The effective voltage at the locomotive is thus kept more or less constant at the expense of not being able to use the full output range of the transformer.

[Anonymous]

Gentlemen,

It just occured to me that the old 167 and 167C whistle controllers, which were the devices that blew the air-whistles during the era before the whistle controllers were built into the transformer, might provide some further illumination for this lengthy-but-fun thread.

Hooked up in series with the transformer, they managed to "manufacture" a "boost" even though there were no compensating windings inside the transformer itself. The circuit diagram at the Olsen's site and the accompanying text might be of considerable interest.

These items (167C) are hard to come by today, but if somebody has one it might prove interesting to hook it up between a modern pure sine-wave
transformer and the track to see whether it would blow an air-whistle.

Caution: I would not use it to energize a modern electronic loco or tender.

Try

http://pictures.olsenstoy.com

and go to the "Library" and then to "Lionel Whistles/Tenders" and move down the column of choices. Be patient -- it's a little slow.

Any thoughts?

wolverine49

[SPFan]

Birds, The circuit is correct but the 1N400x series does not have a high enough current rating for a post war loco. I was thinking of a single component with 4 embedded diodes wired internally as a bridge. Here is one example from Digi-Key:


http://59.120.39.77/mccsemi/up_pdf/MB1005-MB1010(BR-6).pdf

Pete

[cnw1995]

Yep, it's that Lionel sound button. I thought it was a combination of the motors in these Western Hobbycraft trolleys and how the QSI sound board activated - doesn't bother me so much as I remember to compensate for it - but then, I like throttle jockeying. I love that analogy!

[Birds]

Pete,

Is this similar to what you are talking about?

http://www.allaboutcircuits.com/vol_6/chpt_5/5.html

Thanks,
Birds

[Anonymous]

Doug (cnw1995),

This gets curiouser and curiouser. Are you using Lionel 6-5906 Sound Activation Buttons, or some other device, with your venerable Type R?

With what we know (of think we know) I am puzzled as to why some operators report things speeding up, while others report them slowing down when the whistle/horn or bell button is pushed. Could it have anything to do with whether the motors are AC, DC or will run on both?

See the latest three or so posts on this link for some comparisons:

http://www.trains.com/community/forum/topic.asp?TOPIC_ID=61058

I can conceive how a sound button, either built in to a transformer or external, might function even if the transformer had no compensating booster windings. Bob (lionelsoni) suggested this above. Imagine that the throttle is set to14 volts AC. Inserting a sound activation button between it and the track would drop this output by 3 volts to 11, due to a special resistance built into the circutry of the button. Pressing the button would bypass this resistance, thereby temporarily increasing the output to the track to 14 volts. This would provide the boost needed to compensate for the power used by the air-whistle motor, but should also make trains equipped with old-fashoned battery powered horns, and virtually all electronic systems, speed up.*

In this hypothetical cirsuit, releasing the button would re-connect the resistance, thereby reducing ("inhibiting") the power to the track back to 11 volts. Yes?

The question remains, however, whether any modern sound activation devices employ such a circuit? I don't know the answer.

* If the theory behind such a circuit is unclear, consider an analogy. A group of men and women congregating at a bar has a great potential (pun intended) for mischief. Initially these forces are inhibited, but add a little alcohol and the inhibitions get reduced. Buying someone a drink or three is the social equivalent of activating the whistle control, and is often referred to as "pushing the right buttons." The high-voltage is already there -- to convert it into action all that is needed is to reduce the inhibitions. (At least that's how I remember it!)

wolverine49

Note: this was written while Pete's (SPFan) post was popping up. His remarks add a lot, although the cautions are of some concern.

[SPFan]

Modern transformers replicate the DC shift using modern electronics to activate the whistle and bell. A positive shift (center rail to "U" outside rail) activates the whistle and a negative shift activates the bell. Modern locos run conventionally are designed to respond to the same level shifts. I have been able to activate the whistle and bell on Post War engines and Williams engines by inserting a full wave bridge between the transformer and track. No speed loss using this method. Reverse the DC bridge leads to activate the bell. There are two caveats when trying this technique. This may damage modern engines which are not designed to run on DC and you need to use a Double Pole Double Throw switch that has make before break contacts rather than the more common break before make. Otherwise the momentary loss of power will activate the E unit. Most if not all Post War motors are Universal type. That is, they will run equally well on DC as AC. The unfiltered DC may or may not damage modern engines. Definetly don't try and filter it with a capacitor.

Pete

[Jumijo]

On my MRC pure power dual, just the opposite happens when I press the whistle/bell buttons, Doug. It slows the train down and does not activate mechanical air whistles of any kind - modern or vintage.

I'd really like to hear about a fix for this issue. Adding a separate Lionel sound button does not work.

Jim

[cnw1995]

Boy, this sure is interesting. I appreciate your posts, Bob - and your cogent questions, wolve. SO that is why when I press the horn activation button I set up for a transformer (my old 'R') without one, the moving trolley leaps forward, then the horn blows. I always wondered why it speeded it - the same thing happens when I press the bell activation button

[Anonymous]

lionelsoni

Bob, your latest post is as clear and concise as anything I have seen on the subject and is very helpful. Just a couple of more questions:

Are there any concerns about running modern locos (with their electronic sound systems etc.) on old transformers with the "compensatory voltage" boost in the whistle circuit? Shouldn't they tend to speed up? Or even sustain damage if already being operated near the high-end of their voltage range?

The other major remaining issue, as you have noted, is whether modern transformers, which apparently do not have the voltage boost will drive the old air whistles -- without damaging anything?

Anyone want to speak to these issues?

Thanks again, Bob. Super job!

wolverine49

[johnandjulie13]

Hello Bob:

Thank you for the clarification. I appreciate the information. Now, I just need to get my hands on an old postwar engine/tender so I can take it apart and see how all those parts work!

Regards,

JO

[lionelsoni]

The first thing the control does is to insert the 5-volt winding and rectifier in series with the track voltage. The 5-volt winding increases the voltage while the rectifier reduces it by removing the negative half-cycles entirely. The resulting waveform has a strong DC component, which operates the relay, connecting the whistle motor to the track supply. Everything on the track, the locomotive motor, the relay coil, and the whistle motor, all see the same modified voltage. Then the control moves farther and connects the resistor in parallel with the rectifier. This allows much of the negative half-cycles to bypass the rectifier. The DC component decreases, but the relay, already operated, stays operated. The motors see more voltage.

All things being equal, a Diesel will be more likely to speed up when the control is completely operated, since, as you observed, there is no whistle-motor load. There is no provision for adjusting the compensation to match the specific locomotive; and the design was probably developed at an early time with air whistles in mind. To quote the VW service manual, "The two 5-volt compensating windings are normally out of the circuit but are switched in series with the circuit whenever the whistle controller is operated to compensate for the voltage drop in the rectifier and the additional load of the whistle motor." However, there is considerably less total voltage put out in the intermediate position, which was intended to be passed through quickly. This reduced voltage happen to match a particular locomotive; but I suspect that most Diesels would slow down.

I would think that a traditional transformer would have no trouble producing enough jDC to operate any electronic whistle. What a modern "transformer" would do with a traditional whistle relay, I cannot say.

[Anonymous]

lionelsoni,

Bob, you are on a roll again today!

Maybe I could understand this better if you would describe the sequence of events that are supposed to happen with an "ideal train" when one presses the whistle button.

Assume a perfectly operational post-war air-whistle, and a ZW transformer with a perfectly-functioning rectifier circuit, etc.

I know that the ZW has both a "compensating winding" (to add about five volts to the throttle setting) and a two-position switch for the whistle circuit, although the fact that the whistle button slides through two positions may not be immediately obvious to the operator..

Also assume: a modest load, such as 4 freight cars, running smoothly along a (hypothetical) infinitely long stretch of straight-and-level track; at a constant mid-range throttle setting of 11 volts AC.

Now press the whistle button. As the moveable contact in the whistle button encounters the first of the two fixed contacts, what happens? That is, does the whistle relay immediately get a shot of DC? At approximately what voltage? What does the whistle-motor get as the relay passes some current to start and sustain it?

Next, what happens when the whistle button is pushed beyond the first contact and engages the second? Is it now engaging BOTH the first and second contacts? Which component (relay or whistle motor) gets AC, which gets DC and how much?

I'm sure you see where I'm trying to go with this. Obviously the whistle motor needs to draw some level of power to start and run. If the compensating windings kick-in to supply the locomotive motor with approximately the amount of power that the whistle motor requires, the train should neither speed up nor slow down. (As you have said, the Lionel engineers presumably had to "guess" an average-useful value for this,) Is the relay holding "closed" against gravity) on "pure DC at this stage?

In a phrase, what is supposed to happen and in what sequence?

(In actual practice, the train could either speed up (a little) slow down (a little) or stay at the same speed while the whistle motor runs, as you have also stated.)

Now consider the exact same scenario, except subsitute a postwar diesel locomotive that uses a simple DC "bicycle horn" powered by a battery and has no "horn motor." Therefore, it doesn't require any of the ongoing transformer power to drive the sound mechanism, although it does require a small shot of DC to activate and then hold the relay closed. Nevertheless, although it doesn't "need" it , it the diesel receives a compensating shot of approximately 5 volts AC. Therefore, shouldn't the diesel then always tend to speed up, at least a little?

Or, when running a diesel, is there some way for the operator to manipulate the ZW's two-position control button to circumvent the unneeded AC voltage boost?

If I could read the diagrams for the above circuits, I think I would not need to ask these questions, but I can't , and assume that some of the other readers may not be able to either.

If you can clarify this, we might then move on to the issues of using post-war electo-mechanical whistles with modern transformers, and vice-versa -- there are a lot of possible combinations.....

Thanks in advance.

wolverine49

[lionelsoni]

I'm glad you liked the yard throat. Thanks.

1. Yes, it is pulsed at first and, yes, it is at 60 hertz, too fast to notice. When the control is moved all the way, however, most of the missing parts of the waveform are restored. Whether the locomotive speeds up or slows down or neither depends a lot on the load on the transformer. The 5-volt boost and the resistor around the rectifier are just Lionel's guesses at what will keep the typical train moving at about the same speed.

2. A relay is an electrically operated switch. It has an electromagnet that attracts a metal armature to operate the switch. The one used for whistles is, as I described, specially modified to respond to DC but not to AC. There is only one relay; and the older locomotives that use relays have only whistles or horns. It is possible to make a relay that responds only to one polarity of DC; but it would be delicate and expensive.

3. A control that is outside the transformer can be built in one of two general ways: It may simply allow the train to slow down when the voltage is reduced during whistle blowing, since it has no way to boost the voltage to compensate for that lost by the rectifier. Or it can be designed to waste a little power to slow the train down a little even when the button is not pressed, so that there is no difference in speed (or not much) between blowing and not blowing the whistle.

[johnandjulie13]

Hello Bob:

Thank you for the explanation. BTW, I liked your O27 switch setup that you used to set up a freight yard. I have a couple of follow up questions to clarify your comments:

1. When the whistle knob is activated, is there in a sense, a pulsed current?
If the rectifier removes the negative part of the sine wave, then there would be a pulse of current, then nothing, another pulse, then nothing,and so on. Is that accurate? I guess at 60 cycles per second this would not be noticeable in the movement of the engine.

2. I do not know what a relay is. But I am assuming it is "triggered" by the magnetic field of the "DC" current. Is this accurate? Would the engine/tender have two relays, one for the whistle and one for the bell? Each one configured for the appropriate field?

3. If the transformer provides a 5V boost, how does a sound activation button work? Do the diodes in the button provide additional current? Do they draw additional power from the transformer?

Thanks in advance. I am learning a great deal.

Regards,

JO

[Jumijo]

Bob,

I have a new MRC Pure Power Dual transformer. Pure sine wave. It won't blow a mechanical air whistle, and slows down the train when a whistle/horn button is pressed. Can anything be done to fix these issues?

Jim

[lionelsoni]

The DC component of any voltage waveform is simply the average over time of the instantaneous voltage. The symmetry of pure sine wave makes that average zero, so that it has no DC component. With some difficulty, you could add a constant voltage to a sinewave, so that the sum would have a DC component. But the easier method used by traditional transformers is as follows:

When you move the whistle control, it first puts an additional 5-volt transformer secondary winding in series with the normal output and a rectifier in series with that. The rectifier removes the negative halves of the AC cycles, while the 5-volt winding increases the amplitude of the remaining, positive half-cycles to compensate for the loss of the negative ones. The resulting waveform does have an average value, that is, a DC component. As you move the control farther, it puts a resistor around the rectifier, allowing the negative half-cycles to rejoin the waveform, but at a lower level than the positive ones. So the DC component becomes smaller but does not go away completely.

In the locomotive's tender, a "slugged" relay responds to the DC component of the waveform and operates, closing a contact that connects the whistle motor to the track power. In a Diesel, it connects the horn to the dry cell. The purpose of the strong DC component at first is to get the relay operated. Since it takes much less voltage to keep a relay closed after it is operated, the DC component can be reduced after the initial operation.

The slugged relay has a thick copper ring at the end that attracts the armature. That ring acts like a shorted transformer secondary winding and cancels the AC component of the magnetic field produced by the relay coil near that end of the relay. However, it cannot cancel a DC field. So the relay operates only when there is a DC voltage component and ignores the AC component. Modern electronics-rich locomotives use other, fancier circuits to accompli***he same thing. They have the advantage that they can sense the polarity of the DC component and distinguish between positive for whistle and negative for bell.

[phillyreading]

Welcome JO,
An easy way to describe how the electrical current flows for the whistle is to say that it is pulsating DC as straight AC & DC don't mix. You will need to understand what an oscilliscope is & the pattern of AC to understand what it means by pulsating DC or transformer/AC converted DC. Basically AC goes with a positive charge 60 times a second & also goes with a negetive charge 60 times a second referred to as hertz or cycles, pulsating DC fluctuates to the positive side 60 times a second but does not go negative otherwise it would be AC. Pure DC can only be battery voltage. [8D]Hope that this helps as this info is from my high school days.
Lee Fritz

[johnandjulie13]

I am new to the boards and have enjoyed reading the posts. They have been very informative. I have recently read with interest about adding a bell/whistle activation button to a transformers output terminals. However, I am wondering how the voltage change causes the engine (or tender) to make the appropriate sound?

My electronics knowledge is very limited. My understanding is that the activation button will superimpose a dc current onto the ac to trigger the appropriate sound. Is this correct? How does this cause the engine to make the appropriate sound? Also, is it true that this technique is the same for today's high tech engines as it was for engines built 60 years ago?

Thanks in advance for any feedback. I have just started getting involved in the hobby. I am currently planning a small outdoor (G gauge) layout as part of a new patio we are installing this summer and I am planning an O gauge layout for our basement. This way, irregardless of the season, I can have some trains running.

Regards,

JO