I hate dating myself, but back in the 1950's, I had a Lionel train set with what I recall to be a Model Z transformer. This train control had a lever on a spring-loaded switch on both sides of the transformer (two separate circuits) that enabled a whistle located in a locomotive tender or diesel B unit to sound.
I am curious about the electronics involved. What actually occurred to cause the whistle to sound without affecting the speed of the locomotive? The circuit was presumably DC, with the center rail of the three-rail O-gauge track providing the power, while the outer two rails completed the circuit through the steel wheels of the locomotive.
Also, if memory serves, one pushed forward on the transformer switch to have the whistle sound on either circuit A or B, and pushed backward to have the train reverse. Is my recollection correct?
RJ Emery near Santa Fe, NM
What you describe sounds like a Lionel ZW, and yes the control levers do work as you describe.
Lionel trains normally are run on AC, although the postwar ones will work on either AC or DC.
The whistle or horn is controlled by something called a slugged relay, which is unaffected by AC, but closes when powered by DC.
The whistle control switches a copper-oxide rectifier into the circuit, in parallel with a resistor. This arrangement allows a small amount of DC leakage into the AC waveform-just enough for the relay to close.
ben10benThe whistle or horn is controlled by something called a slugged relay, which is unaffected by AC, but closes when powered by DC. The whistle control switches a copper-oxide rectifier into the circuit, in parallel with a resistor. This arrangement allows a small amount of DC leakage into the AC waveform-just enough for the relay to close.
Any idea where there may be a further discussion of that feature and application along with how the reverse switch effected a change of direction? I am totally unfamiliar with the electronics involved but would like to understand more specifically as well as how Lionel trains in the 1950's operated in general.
The designation ZW also rings a bell, so I appreciate the correction.
http://cs.trains.com/trccs/forums/p/80974/963192.aspx#963192
Bob Nelson
The Postwar Handbook has some fairly good explanations and of course the wiring diagrams for the various transformers.
I've noticed with my RW-110 that the train has a burst of speed when the whistle is activated. When I repaired the transformer I replaced the copper-oxide disc w/ a newer model rectifier diode sold for the task. I understand why this occurs, but how well does the shunting resistor compensate for the increased voltage?
Bob
Tucson, AZ (aka the Ol' Pueblo)
Home of the Mt. Graham & Arizona Eastern Boiler Shops
Bob,
submmbobThe Postwar Handbook has some fairly good explanations and of course the wiring diagrams for the various transformers.
Which handbook is that? Are copies still available?
I've noticed with my RW-110 that the train has a burst of speed when the whistle is activated.
I seem to recall the same burst of speed with the ZW, I think when there was no whistle enabled locomotive running on the tracks. Still, it is a puzzle to me how a DC spike over an AC waveform would produce such an effect. Too many decades have gone by to reproduce the effect.
The 5-volt winding approximately compensates for the diode initially, before the switch connects the shunting resistor. When the transformer is set to 12 volts RMS, the winding bumps this up to 17 volts RMS; but the diode removes half of this waveform, dropping the RMS voltage back to 12 volts, for no net voltage change. At higher transformer voltage settings, the RMS voltage drops a little; at lower settings, it rises a little.
Then, when the switch connects it, the shunting resistor restores part of the removed half of the waveform, both boosting the RMS voltage and reducing the DC component. The amount of this boost depends on how much current the train is drawing. It is meant to compensate approximately for the increased current drawn by the whistle motor; so locomotives with battery-powered horns instead of whistles are likely to speed up when the horn blows. You may be able to avoid this effect by disconnecting the resistor, or by simply moving the whistle control only part way.
RJ - the handbook I am referring to is Greenberg's Repair and Operating Manual for Lionel Trains 1945 - 1969. It is still in print and available for around $25. I find it very useful and wish the prewar version were still in print.
Bob - I've noticed the train doesn't speed up as much if I only push the whistle button part way. Although the whistle only blows momentarily. If the shunt resistor was removed would there still be enough holding current to keep the relay closed as long as the button was being held down?
I don't understand why your whistle blows only momentarily. The greatest DC component exists before the shunting resistor is connected. At the 12-volt setting, it is about 5 volts and should operate your relay very solidly and keep it operated. Is it possible that your relay is closing but that the whistle is not getting enough voltage to run?
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