Abstract: The disclosure is directed to a lid latch concealed in a tamper-proof enclosure and a centrifuge interlock circuit which prevents the opening of the lid latch until the rotor has come to a full stop, and which requires electrical power to release the latch. Rotation is detected by a low level direct current applied through a sensing resistor to the brushes of the drive motor, after drive power to the motor has been cut off. Any rotation will cause rapid modulations of the current through the sensing resistor, which develop a corresponding signal voltage across the resistor. The signal voltage is amplified and applied to trigger a clamp circuit, which overrides a lid latch release device until rotary motion has ceased.