Michael Sy

You can order the stayin alive kits from some manufacturer directly. But I do not know the size is small enough for you or not. Below is the information I found for your reference. LaisDcc/860009 Stayin Alive Kits Pro/Price at 12USD http://laisdcc.com/decoders/ The LaisDcc Stayin Alive Kits Pro are used to supply power to decoders during times of power interruption due to dirty track or problematic track work It will power an HO Scale locomotive with headlights on for approximately 6 to 20 seconds (depending on the locomotive and the efficiency of the motor). It includes a blue and a black wire with which to attach it to a decoder. The blue wire is the positive/DC+, the black wire is the GND. You can use it with sound decoders and mobile decoders. Dimensions: 26mm x 11.4mm x 8.8mm PS: This parts not support current version of LaisDcc Decoders. Will support with future version of decoders that will coming soon. Michael

https://sites.google.com/site/markgurries/home/decoders/keep-alive-compatibility http://www.members.optusnet.com.au/mainnorth/alive.htm http://laisdcc.com/Stayin_Alive_laisdcc.pdf You can find a very detailed description about keep alive or stay alive or stayin alive at above link.

Mick, you can use 470uF Tantalum Capacitor in parallel. But the the energy capacity in Joules is very limited.