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Post by jwar on Oct 17, 2014 17:47:32 GMT -5
Wondering if a capacitor could be installed on engines with older decoders to make it act like a keep alive. Would be nice if I or we could add an component ahead of the decoder (perhaps between track power and decoder), to prevent short engines from stalling on insulated turnouts as the keep alive will run a second or more after power disruption, Also helps with dirty track of which is not a concern for me.
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Post by Mark R. on Oct 17, 2014 20:07:23 GMT -5
A keep alive module (commercial unit or home brewed) can be installed on any decoder. It MUST be installed on the inboard side of the bridge array of diodes on the decoder for two reasons .... 1 - If it was between the decoder and the track, it would just constantly drain back into the track, and 2 - capacitors are a DC component (polarity sensitive) so they must be on the rectified side of the decoder. This site shows how to install one on a good variety of decoders .... www.members.optusnet.com.au/mainnorth/alive.htmMark.
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Post by jwar on Oct 18, 2014 12:52:31 GMT -5
Thank you Mark..extremely informative and thanks for the reply. There is a capacitor (has a different terminology, works the same for AC) for AC voltage between 3 and 40V, What is your valued opinion of this with a diode prevent drain back to track, installed on the AC side between the decoder and the track. Wondering if this could be a simplistic fix, and if the manufactures are keeping it complicated for decoder sales Again Thanks Mark
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Post by Mark R. on Oct 18, 2014 13:25:36 GMT -5
The trouble with a bi-polar capacitor is it is physically much larger than a polarized capacitor of the same value. A bi-polar capacitor is essentially two polarized capacitors wired in reverse series in a single package. A bi-polar capacitor is used more as a filtering device as opposed to a storage device.
The aftermarket stay alive modules use super-capacitors which have a capacitance hundreds of times higher than a normal AL capacitor. I'm sure if there WAS a simpler way to do it, we would be doing it by now.
Mark.
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Post by jwar on Oct 18, 2014 14:03:59 GMT -5
Well it was one of those morning awaking light bulb moments. LOL Again thanks Mark, I learnrd a lot from ya
John
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