Described in this paper is the tuning fork for self-excited oscillation to be used for accelerometer calibration up to acceleration of 1500g.
This equipment is composed of a tuning fork, capacitor as mechano-electrical transducer, Inoue's circuit, amplitude limiting circuit, power amplifier and electro-magnetic vibration exciter. Each fork is equipped with an accelerometer to be calibrated and a balancing mass.
In calibration operation, first the tuning fork vibrates when it is tapped and then a capacitor picks up the electric signal having a frequency only of vibration. The electric signal is amplified up to specified value and then sent to the electro-magnetic exciter coil. As its result, the tuning fork makes a self-excited oscillation in a constant amplitude value.
This equipment is very good for use in accelerometer calibration because this tuning fork always resonates independent of the weight of accelerometer.