Aristo-Craft pulse width control (PWC)

Aristo-Craft's Pulse Width Control (PWC) test measurements Vignette
Ted Doskaris
May 15, 2007
Revision GE-B

For information about PWC see the below link for Aristo's Tech Support article, "What is P.W.C.?"
(need new link to this article if it can be found)

Also, relevant to my test - see  George Schreyer's below link sub topic:
"PWC in the ART-5471 Train Engineer"
 within the "Aristo PWC Tips" page.

http://www.girr.org/girr/tips/tips3/pwc_tips.html#5471

With respect to Aristo's PWC, I decided to actually do some test measurements using an oscilloscope and multimeter to see what is actually happening with my particular equipment as the following will illustrate:

The pictures below show the results of the tests.

Aristo-Craft Ultima unregulated power supply ART-5460 and Train Engineer Receiver ART-5471 used for the PWC measurements:


Aristo-Craft PWC electrical load test train comprised of one SP GE-9, two Wisconsin Central SD45s and 32 100 ton hopper cars:


Tektronix model 2213 60 MHZ Oscilloscope Channel 1 set at 5 volts / cm, DC coupled, Sweep set to 5 microsec / cm.  (These are the settings used for the PWC measurements seen in the subsequent pictures.)


The scope waveform below shows the PWC as measured across the track rails with the test train operating at a CRAWL speed.
The digital multimeter to the left of the scope indicates an integrated value of dc voltage of 5.27 vdc which is indicative of what the locos' perceive whilst operating with the scope waveform of 14 volts peak of about 18 microsecond pulse width duration.  The Ultima amp meter indicated a 1.8 amp output value.
(Note the pulse repeat duration of 43 microseconds (e.g. 23.2 KHZ rate)  does not change for all the tests as can be seen in the subsequent waveform pictures.)

(The panel with switches and LED status indicators below the scope has nothing to do with the tests; it is my turnout remote control panel.)

The scope waveform below shows the PWC as measured with the test train operating at a SLOW speed.
The digital multimeter to the left of the scope indicates a voltage of 7.31vdc which is indicative of what the locos' perceive whilst operating with the scope waveform of 14 volts peak of about 23 microsecond duration. The Ultima amp meter indicated a 2.5 amp output value.


The scope waveform below shows how the PWC responds with the test train load removed (via a toggle switch set to off position removing track power as the train traversed a siding).
The train had been operating at slow speed as in the above test, and the Train Engineer remote transmitter was not changed or otherwise commanded. (Notice how the PWC wave form increased to 19 volts peak - whilst the mutlimeter was indicating 9.85 vdc - but the pulse width duration was about the same. Remember, the Ultima power supply is unregulated.)


The scope waveform below shows the PWC as measured with the test train operating at a FASTER speed.
The digital multimeter to the left of the scope indicates a voltage of 10.02 vdc which is indicative of what the locos' perceive whilst operating with the scope waveform of 14 volts peak of about 32 microsecond duration. The Ultima amp meter indicated a 4 amp output value.


End