Abstract: Low voltage switched loads, such as magnetic tape write drivers, require a power source with a regulated voltage. A voltage regulator circuit includes a switched voltage regulator having an unregulated voltage input connected to an unregulated voltage source and an enabling input. The voltage regulator produces a regulated voltage at an output when the enabling input is asserted and produces high impedance at the output when the enabling input is unasserted. A capacitor is connected between the regulated voltage output and common voltage. A controlled precharge switch in series with a precharge resistor is connected between the unregulated source and the regulated voltage output. The precharge switch has a precharging input which closes the precharge switch when the precharging input is asserted.

Abstract: Initial start up conditions for an oscillator having an inductor and capacitor coupled as a frequency determining resonant circuit are established by current generators. The current levels correlate to the steady state operating levels of the oscillator. Switching elements are actuated so as to gate the oscillator into immediate steady state operation without start up transient distortion by reconfiguring the relationship of the current sources to the oscillator elements.

Abstract: A system for reading information stored on a flexible magnetic disk is disclosed. The system involves an amplitude detector for detecting at predetermined times whether the amplitude of the read signal is positive, zero or negative. This system includes an amplifier for the differential raw data signal whose gain is variable in response to changes in the amplitude of the raw data signal which occur over a relatively long period. The output of the automatic gain control amplifier is an equalized differential signal applied to the detector and to a threshold generator which provides an output reference signal which is a predetermined percentage of the input signal, and which is capable of following relatively rapid changes in the amplitude of the input signal. A positive and negative comparator circuit continually compares the differential equalized data signal against the generated threshold reference signal.