http://www.eio.com/repairfaq/sam/laserapd.htm
Battery Backup System for Large Aircraft.
http://www.uoguelph.ca/~antoon/gadgets/backup.htm
Small system or Receiver Backup Power.
http://www.uoguelph.ca/~antoon/gadgets/rxback.htm
http://www.xtronics.com/batterap.htm
a single LED indicates whether the battery charger s delivering a trickle charge or a fast charge, cricuit designed to charge 2-14 cells
http://www.edn.com/archives/1995/052595/11di1.htm
NiCad Battery Cycler for RX & TX.
http://www.uoguelph.ca/~antoon/gadgets/cycler.htm
http://www.shaka.com/~kalepa/desulf.htm
NiCd discharger by John Nooyen.
http://www.uoguelph.ca/~antoon/gadgets/disch.htm
http://www.solorb.com/elect/solarcirc/lvbeep/index.html
for Pinball Machines
http://www.zaccaria-pinball.com/misc/vbat/