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Discussion Starter #1
I know there are keep/stay alives that you wire into your control module.. But has anyone put a capacitor ( high mF one ) in parallel with the dc drive motor in your engine.. ..
I was wondering if the cap would provide that short burst of current to get your engine over a dirty spot.. Like the stay alives do... your lights ect might flicker , but your engine would at least continue on to a clean spot..
Enlighten me electronic guru's...
 

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Keep in mind, the loco motor is DC and the decoder will reverse the polarity when
told to back up...caps don't like reverse polarity.

Don
 

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yes, it does work with reverse protection diodes ... [two caps]
about the same as having momentum turned on ...
not really worth it, from experience ..
 

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Discussion Starter #5
But... RC cars had them, I know they were more for noise ( radio interferance) . . they would use 2 caps.. 1 lead to the motors terminal and the other to the can of the motor, one cap off each terminal... believe me rc cars do alot of forward and reverse.. they were were ceramic caps if that means anything...so they did it somehow..
 

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Discussion Starter #6
OK... I guess just stick with keep alives... There are a lot of schematics out there to build them.. so will look into it more.. Biggest problem is fitting the keep alive in the engine...
 

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those capacitors weren't the stay alive versions ... they were just there for EMI suppression, sorry, either one doesn't really help on a straight dc motor [in a model train] .. DCC works differently ..

or just find out yourself when you blow up a single electrolytic capacitor on a DC layout, yes it will happen, rofl!
 

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If your thinking of doing this on a DCC locomotive, the power to the locomotive is not straight DC, is a pulse width modulated signal and on some decoders shuts off momentarily to collect back emf data. So even if you put in all the circuity to handle the + and - voltage, you still might toast the decoder. The keep alive is buried in the decoder circuitry where there is a constant DC voltage made that drives the decoder, which makes it easier to attach large caps at this point.
 

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I never felt the need for a 'stay alive' circuit...I had 10 DCC locos running on a room size HO flex track layout with more than 20 Peco
Insulfrog turnouts. Any time I had a loco stall or pause, there was a track or loco power pickup problem ...my loco
headlights never blinked otherwise. Keeping the track and loco wheels clean is mandatory for smooth operation.

Don
 
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