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I have only tested DC with PWM and DCC with a DCC decoder. I haven't tried a plain DC motor on a DCC system. Imagine I could someday but don't feel any driving need to do so. I was reacting to the extensive reporting of coreless motors being destroyed by PWM control and found it to be as described above. I have seen the reports of decodered units going bonkers on DC with PWM control, some controllers worse than others such as the origin of this effort by Max, and I can envision a problem as has been described due to the decoder being confused by the PWM frequency. I wouldn't expect the 1300 controller or any other to cause trouble with a DC motor as long as the max voltage seen by the motor doesn't exceed the motor's rating. It will be interesting to see Max's results.
...the pulse peaks are at 25 volts in amplitude...
The 1300 puts out full-wave sine pulses where every other pulse is much lower in amplitude. So you might see 10v pulses interspersed with 4v pulses. As you turn up the throttle, the intermediate low pulses climb until at full throttle, they are equal to the others, and you get a standard full-wave rectified, un-smoothed DC output. Just sine pulses. Normally, this would be no surprise and would not hurt a motor or any other circuitry. But... the pulse peaks are at 25 volts in amplitude, which strikes me as inordinately high.
I wonder what the ratings label on the 1300 shows for the AC accessory and for the track voltages. Can someone provide that info?
We have to remember that many DC power packs are rated, voltage wise, fully loaded. I know Max had a grain-of-wheat bulb loading the pack but that wouldn't load it to its maximum, 1 amp or 2 amps, or whatever and if the pack isn't regulated, the voltage will be all over the place depending on the load.Is the 1300 fully regulated, putting out the same maximum voltage regardless of load or is it like most DC packs and the maximum is greatly dependent on load?I am aware that most modern, solid state packs have a regulator in them, unlike the old rheostat packs but does the 1300? I assume it's a transistorized pack.Doug
1300 is transistorized and Max promised me that he will trace a circuit diagram. I'm pretty sure is not regulated or even filtered DC.As for the voltage specs, I suppose Max might be able to load it to the maximum load and read the voltages. But the fact is that most modern locos will only used fraction of the rated amperage (both DC and DCC), so the voltage will be at the high end.
The 1300 puts out full-wave sine pulses where every other pulse is much lower in amplitude. So you might see 10v pulses interspersed with 4v pulses. As you turn up the throttle, the intermediate low pulses climb until at full throttle, they are equal to the others, and you get a standard full-wave rectified, un-smoothed DC output. Just sine pulses. Normally, this would be no surprise and would not hurt a motor or any other circuitry. But... the pulse peaks are at 25 volts in amplitude, which strikes me as inordinately high. Even though the average DC is only about 16 volts, that is still way higher than necessary for N or HO motors. And imagine what would happen if you connected a piece of electronic circuitry to the track that isn't just a simple resistive or inductive load like a motor. Would 25 volt peaks hurt it?By comparison, the Tech II 2500 is actually a PWM throttle (who knew!). I scoped it, and it puts out square pulses that start around 0.4 mSec in length and just gradually lengthen as you turn it up. But the pulses are only 19 volts in amplitude.Both of these tests were done with a 50 ma grain-of-wheat lamp load on the throttle, so it's not just "floating" with no load.-----------------------------------I'll be very eager to see info on the scoping of those other MRC packs. I hope metalworkertom will be able to chime in here with his results.I am not certain, but I sure am developing a strong theory.
A couple of pics. Not much to it.
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Topic: Railpower 1300 testing (Read 41040 times)
