Nominal Voltage Drop for 167 Whistle Controller Choke Coil?

4-5 volts for initial "pickup" of the whistle solenoid, 2-3 volts holding for the 167.

ADCX Rob posted:

4-5 volts for initial "pickup" of the whistle solenoid, 2-3 volts holding for the 167.

But isn't the choke out of circuit for the pickup and hold portions of the button's travel (positions 3 & 4)?

• Position 1 (Button not depressed): Choke only
• Position 2 (Affects a “make before break”): Choke + rectifier
• Position 3 (Pickup surge): Rectifier only
• Position 4 (Button fully depressed, holding position): Rectifier + full AC across 1-2 ohm shunt

I'm dropping 5V+ AC when in Position 1 and wondering if it should be that much.

Rob,

I have those service sheets too - but they don't say what the nominal AC drop of the choke all by itself is, hence my question.  

Below I pieced together the “known” nominal values from the service documentation as well as four unknowns.  Below I assume the supply is 10V AC, x is the coil’s nominal AC voltage drop, y and z are AC voltage drops at various positions not defined in the service sheets nor is the n DC V)

• Position 1 (Button not depressed): Choke only, (10-x V AC, 0V DC)
• Position 2 (Affects a “make before break”): Choke + rectifier (10-x-y V AC, nV DC)
• Position 3 (Relay pickup surge): Rectifier only (0V AC, 3-4 V DC)
• Position 4 (Button fully depressed, relay holding position): Rectifier + non-choked AC across 1-2 ohm shunt (10-z V AC, 0.6 V DC)

I was originally interested in x, but y, z, and n would be useful to know as well.  Or perhaps not. 

If my thinking is clear, to compensate for a PW whistle's motor x should be somewhat greater than z.  To compensate for an electronic whistle (which the 167 wasn't of course designed for) x should roughly equal z.

Since the choke is in series with the load (train)., isn't the voltage drop going to vary depending on the load?

The specs are in the transformer section of the service manuals.

CharlieS posted:

Since the choke is in series with the load (train)., isn't the voltage drop going to vary depending on the load?

Good point - although that does muddy the problem a bit more.

JTrains posted:

CharlieS posted:

Since the choke is in series with the load (train)., isn't the voltage drop going to vary depending on the load?

Good point - although that does muddy the problem a bit more.

That is, of course, by design.