Reverse polarity flyback switch

Claim 1

A driver circuit for N coils of the type having respective first and second terminals, and wherein said coils are controllably energized by an external source of electrical power, comprising: N control switches each coupled in series between a first terminal of an associated one of said coils and a first common junction, said first common junction being normally connected to a positive reference terminal of said electrical power source, said control switches being adapted to controllably connect said coil first terminals to said power source positive reference terminal in response to said externally supplied control signals, said coil second terminals being connected at a second common junction, and said second common junction being normally connected to a negative reference terminal of said power source; N flyback diodes each having a cathode connected to a respective coil first terminal and an anode connected to a third common junction, and said third common junction being normally connected to said power source negative reference terminal; and a switch connected between said third common junction and said diodes, said switch being biased to a first position in response to said first and third common junctions being connected respectively to said power source positive and negative reference terminals and a second position in response to said first and third common junctions being connected respectively to said negative and positive reference terminals, and wherein said flyback diodes are electrically connected to said third common junction when said switch is at said first position and said diodes are electrically disconnected from said third common junction when said switch is at said second position.