Johndc120 Posted January 21, 2020 Share Posted January 21, 2020 Some help required. Subject - problems with sprog and stay alive decoders I have fitted several locos with TCS chips and large capacity stay alive. I use a digitrax zephyr to test my stock and they all run correctly and the capacitance keeps the locos going for a decent length of time. On the exhibition layout we have a sprog permanently attached to the layout. It runs other locos with no trouble however as soon as you put a loco with a large stay alive on the track the sprog shuts down (detects short) Has anyone else had a similar experience and is there anyway around this without reducing the capacity of the stay alive? TIA John Chivers Link to post Share on other sites More sharing options...
Crosland Posted January 21, 2020 Share Posted January 21, 2020 Are you putting the loco on the track whilst the power is on? Exactly how big are the stay alives? 1 Link to post Share on other sites More sharing options...
grriff Posted January 21, 2020 Share Posted January 21, 2020 I'm also interested in this question since I have a SprogII and am intending to fit a large Stay Alive from DCC Concepts (ZNSSA). They don't quote a capacity. 1 Link to post Share on other sites More sharing options...
Johndc120 Posted January 21, 2020 Author Share Posted January 21, 2020 2 hours ago, Crosland said: Are you putting the loco on the track whilst the power is on? Exactly how big are the stay alives? It’ll do it either way, if you power up with the loco on the track then it shuts down and also if the loco is on the cassette and you plug the cassette in it shuts down too. the capacitors are 6800uf so they are pretty big. I’m wondering if I need to up the size of the resistor to restrict the inrush current Link to post Share on other sites More sharing options...
Nigelcliffe Posted January 22, 2020 Share Posted January 22, 2020 6800uF is "middling" in capacitor sizes. But, what in-rush and discharge diode control do you have ? TCS' own modules (the KA series) are up to at least 160,000uF equivalent, and are fine with the inrush resistors on the KA modules. I think that's around 100ohm, so the in-current would be in the region of 150mA. - Nigel Link to post Share on other sites More sharing options...
Crosland Posted January 22, 2020 Share Posted January 22, 2020 Yes, I would try increasing the resistor. The SPROG does shutdown very quickly to protect itself, but has a longer delay on power up to cope with inrush current, which can be surprisingly high with even modest capacitors. 1 Link to post Share on other sites More sharing options...
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