High speed centrifuge and speed control circuit therefor

Claim 1

A SPEED CONTROL SYSTEM FOR MOTOR DRIVEN DEVICES INCLUDING MOTORS OF THE TYPES HAVING ROTOR AND FIELD WINDINGS COMPRISING A TACHOMETER MOUNTED TO PRODUCE AN ELECTRICAL POTENTIAL HAVING A MAGNITUDE DEPENDENT UPON SPEED, A SOURCE OF REFERENCE POTENTIAL, MEANS FOR RECEIVING THE TACHOMETER POTENTIAL AND THE REFERENCE POTENTIOL AND PROVIDING AN DIFFERENCE SIGNAL, AN AMPLIFIER CONNECTED TO RECEIVE SAID DIFFERENCE SIGNAL AND PROVIDING A FIRST OUTPUT SIGNAL WHEN THE DIFFERENCE SIGNAL IS ABOVE A PREDETERMINED LEVEL AND A SECOND OUTPUT SIGNAL WHEN THE DIFFERENCE SIGNAL IS BELOW SAID LEVEL, A SOURCE OF POWER FOR DRIVING SAID MOTOR, MEANS FOR CONTROLLING THE POWER APPLIED FROM THE SOURCE TO THE MOTOR IN RESPONSE TO SAID FIRST SIGNAL TO CONTROL THE SPEED OF THE MOTOR IN A DESIRED DIRECTION, SWITCHING MEANS INCLUDING A CIRCUIT COMPRISING A COIL CONNECTED IN PARALLEL WITH THE CAPACITOR AND IN SERIES WITH THE RECTIFIER RESPONSIVE TO THE SECOND SIGNAL FOR REVERSING THE DIRECTION OF CURRENT IN THE FIELD WINDING AND APPLYING