Testing a Lionel 167 Controller on a Lionel Z Transformer ?

[MickeyDemian]

Hello All:

  In attaching a 167 controller to my Z transformer,  I was using my voltmeter to see if the whistle button activated any change in my voltmeter reading .  Far from an electrical guru I am, so I am asking if I should ecpect any change in the maximum 24.8 volts I see on my meter when I push the whistle button and have the Z at max power?  Presently there is no change or inflection.   Now the whiste rectifier disc activates a DC surge, correct?  So should I be measuring in a different current type?  Bottom line is- I am trying to see if my 167 controller will work this Xmas under the tree or be a dud.   How can i test it?  Thanks for the help and knowledge shared.

  Mickey Demian

[lionelsoni]

You need much more of a load than a voltmeter before you will see anything other than the full type-Z voltage.  With a train drawing a few amperes, there will be a drop of a few volts in normal operation.  This is due to an inductor (choke) in the 167 that will be in series between the transformer and the track.  Fortunately, the type-Z has voltage to spare.  When you push the whistle button, the inductor will be replaced by a copper-oxide rectifier.  Then, as you push it farther, the 167 will put a resistor in parallel with the rectifier, to supply the additional current drawn by the whistle motor.  Through all this, the voltage at the track should be roughly unchanged, although, with a diesel horn or a modern electronic whistle, neither of which draws much current, the voltage may rise when you bottom out the pushbutton.