I was reading a Greenberg book I just bought and it mentioned using a whistle relay to activate electromagnetic couplers. I thought this would work really well in a PW diesel switcher doing way freight ops. At my level of expertise, I can conceptualize the idea that by putting a whistle relay in a loco like a 623, you could operate the loco's couplers anywhere on the layout by hitting the whistle control on the transformer, but I would be lost as to the particulars regarding modification and installation. The reason I would do this is because I like the idea of using postwar tech to achieve something that could easily be done using modern technology. So, has anybody done this, or what do you all think?
I don't use the whistle signal; but I can uncouple anywhere. I have a little circuit that looks at the motor field voltage to discharge a capacitor into the coil of a relay which switches track voltage to the coupler. The capacitor is continuously supplied with charging current when there is track voltage, but can't actually build up a charge unless the locomotive is in neutral.
The way it works is: I stop and go into neutral for a few seconds. The capacitor charges. I turn the track voltage off and on, to shift into forward or reverse, as appropriate, and the relay operates for a second or so as the motor starts, until the capacitor discharges, and the coupler buzzes while the relay contact is closed. I pull away from the train.
Bob Nelson
I use the "teledyne" system. Where the whistle relay does the uncoupling. I love it. I've had my 623 rigged up with teledyne for a few years now. Infact, being wiring challenged, Bob Nelson helped me wire it a few years back. Thanks again Bob!
I had to fashion a bracket and insulate using a rubber washer from the front truck but it works perfectly every time.
Mike S.
In the Oct 2007 issue of CTT there is a one page article describing exactly what you want to do.
Years ago I set up a 520 to use a whistle relay to control the e-unit. Same idea, different function.
lionelsoni I don't use the whistle signal; but I can uncouple anywhere. I have a little circuit that looks at the motor field voltage to discharge a capacitor into the coil of a relay which switches track voltage to the coupler. The capacitor is continuously supplied with charging current when there is track voltage, but can't actually build up a charge unless the locomotive is in neutral. The way it works is: I stop and go into neutral for a few seconds. The capacitor charges. I turn the track voltage off and on, to shift into forward or reverse, as appropriate, and the relay operates for a second or so as the motor starts, until the capacitor discharges, and the coupler buzzes while the relay contact is closed. I pull away from the train.
cwburfleYears ago I set up a 520 to use a whistle relay to control the e-unit. Same idea, different function.
Lionel calls this "Magic Electrol"
Rob
NishSo, has anybody done this, or what do you all think?
It works great. Go for it!
Looks like 'Magic Electrol' would be a cure for e-unit buzz?
Yes, but your couplers will activate at the same time. In reality, it's one or the other.
If you use 2 solid state polarity sensitive whistle control boards(610-8633-010), it can be done.
David, first let me warn you that I have put rectifiers in my locomotives (for another purpose) so that the uncoupling circuit only has to contend with DC of one polarity. At one time I had a much more complicated circuit that could tolerate either polarity of voltage, but I don't think I have any record of that.
I will call the negative side of the locomotive's DC motor supply N and the positive side P. The circuit is, from P to N, a signal diode with anode to positive, a charging resistor, an electrolytic capacitor, and the relay coil. The coil has a signal diode in parallel with the cathode to N. This allows the P voltage to charge the capacitor, with the charging current bypassing the coil to N. There is also an NPN transistor. Its emitter is connected to N and its collector to the positive terminal of the capacitor. Its base is connected through a resistor to the positive side of the motor's field coil. So, whenever the motor is run, the transistor turns on and connects the positive side of the capacitor to N. If the capacitor is charged, its negative side becomes more negative than N, applying the capacitor voltage across the relay coil and operating the relay for a second or two.
Can you reverse the polarity on the whistle relay and trigger it with the bell button? Or would that be a different part?
I know on my Teledyned 623, both the whistle and bell button trigger the couplers. Actually the Bell button seems to do it with more juice so the action is quicker. Not sure why.
It will already work with the bell button, by design. The relay is not polarity sensitive.
Thanks, I wonder if you could install a diode on each coupler so one would open on the bell and the other on the horn?
Diodes at the coupler would work with a traditional transformer, but only if you didn't move the whistle control all the way. In the first stage, the whistle control circuit puts half-wave DC on the track. This operates the relay, which switches the same half-wave DC to the coupler. This scheme probably would not be practical with a modern "transformer" that uses some other method of superimposing the DC on the track voltage. Furthermore, you would need to construct a bell controller that worked the same way as the traditional whistle controller; or you could use a DPDT switch to swap the transformer terminals according to which polarity you need. This would be practical only with a single-output transformer, where there is no issue of which transformer terminal is common.
I don't see the need for opening only one coupler however. When you uncouple a locomotive from a train, your next step is to move the locomotive away from the train. That inevitably moves it toward whatever it might be coupled to on the other end, reclosing that coupler.
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