Accelerometer Schematic:

ADXL202 Accelerometer to C Volt Output: The Air Whammy is a simple dual control voltage generator that uses a 2 axis accellerometer as the source. The whole circuit fits into a small project box (approximately 65x40mm), and is powered from a 12V AC plugpack. 

Switched-capacitor IC controls feedback loop: 02/17/00 EDN-Design Ideas  /  You can implement a simple control loop with a constant setpoint over a wide range of control by using a switched-capacitor filter. The circuit controls motor speed over 1 to 200 Hz or 60 to 12,000 rpm. In Figure 1 , a National LMF40CIWM four-pole lowpass...