Bryan Mumford, Crackpot Inventor

Original circuits for antique electric clocks

These links describe a variety of devices available for improving old electric clocks, or for making your own.

Slave Driver
An electronic Master Clock for old slave dials --- turns slave dials into functioning clocks
  or will synchronize Western Union and Self Winding clocks at the hour
Le Slave Driver
An electronic Master Clock for antique European slave dials like French Brillie and ATO
  This version outputs the alternating polarity required by many Eureopean slaves
Semiconductor switch

An electronic battery that makes Eureka, Bulle, and Brillie clocks keep quartz accurate time

Semiconductor switch

A way to make antique battery clocks more reliable

EM controller

A complete electronics package for making your own accurate electromagnetic clock