Just saw this from Iowa Scaled Engineering (ProtoThrottle), tiny size, $19. Maybe something for the HO crowd?
https://www.iascaled.com/store/Run-N-Smooth/CKT-DCCSA"The Run-N-Smooth PowerKeeper is a micro-size stay alive module that improves the running quality of N-scale and space-constrained DCC locomotives. With integrated protection circuitry and built using micro capacitors, the Run-N-Smooth PowerKeeper provides a simple, easy, and safer alternative for small installations.
While not a stay-alive in the traditional sense (these will not provide multiple seconds of sound+lights+motor over dead track), the Run-N-Smooth PowerKeeper will provide a noticeable and much needed insurance against rail and wheel oxidation, mild dirt/grime and slight tracking imperfections. With N-scale’s smaller wheel-to-rail contact area combined with it’s lighter weight, reliable DCC operation is of greater concern than in the larger scales. With the Run-N-Smooth PowerKeeper, stalling, annoying sound drop-outs, and flickering lights can be a thing of the past!"
