The Circuit Breaker principle is used on numerous type of BTM Punched Card equipment. However, 26-way cams are unique to the Bombe. Paul Kellar kindly produced these for us in his home workshop.

The circuit breakers themselves are standard BTM parts. They are arranged in pairs with their contacts wired in parallel. The position of the cams is such that one cam will make and break earlier than the other. This arrangement allows the front and the back of pulses to be individually adjusted at the ‘points’.

As can be seen below the Circuit Breaker unit is now assembled but has yet to be set up with the correct timing.

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