Wednesday 10 September 2008

More DCC Decoder Trials

Back in February I ran a few DCC Decoder Trials, the outcome being that Zimo and CT were considerably better on small motors than Lenz Mini Silvers.

Over the summer, I've added more Zimo and CT chips to my locos, and been very happy.

With various forums singing the praises of cheaper chips, I thought it worth trying a couple on locos which don't see regular running, so I've added a couple of cheaper decoders into the testing.
A Digitrax DZ125, intended for a Hornby Class 24 owned by the local Scalefour group and a TCS M2 for a 7mm scale Sentienel. Both chips cost half the price of a Zimo or CT. The Digitrax is sold as a small decoder for N, the TCS is a tad bigger, but I understand TCS have similar functions in a smaller package.

Neither has any comment in the manuals about coreless motors, so I'm not inclined to risk my £30/piece small coreless to them, and anyway, they are quite chunky decoders so if I had room for the decoder, I'd have room for a bigger motor !

Test locos were therefore fitted with a Mashima 1016 open framed (my standard test loco) a Mashima 1216 flat-can (the 7mm Sentinel), and a pancake motor (Class 24 diesel). I tried the chips in each to see what the results would be.

I had a fiddle with decoder settings:
TCS seemed best to leave the BEMF function on and not try to use the "dither" control. Best results were obtained if I only altered the speed curve.
With the Digitrax, I fiddled extensively with the motor compensation settings when trying to make the Class 24 run well, and a significant improvement was noted.

Slow speed starting was OK, but not spectacularly good. With the Class 24 both struggled, the Digitrax "wobbling" slightly faster and slower, the TCS smoother but not quite as capable at the crawl.

Of the locos, the 4mm Railbus (Mashima open framed) is keeping the TCS. The 7mm Sentinel will have the Zimo, plus 1000uF of capacitors for an uniteruptable supply. The Class 24 diesel will keep its Digitrax.

Control is reasonable with these decoders, but it falls a long way short of Zimo, CT in slow speed motor control.

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