I hope this helps.
Joe Fugate had some info in the past regarding fast clocks. I only managed to find one of the threads. Here it is: http://www.trains.com/trccs/forums/337033/ShowPost.aspx
Send him an e-mail as he might have acquired more info since then.
"I like my Pullman Standards & Budds in Stainless Steel flavors, thank you!"
Is there anybody out there that knows how to build a fast clock for HO? If so I would like to see a schematic and list of parts
Thank You
rmayer