Abstract: In an optical pattern tracer which uses sample and hold circuits for signal processing filtering of the signal to reduce undershoot can be attained by manipulation of the sample and hold processing circuits. The present application varies the holding capacitor to produce a varied low pass filter effect.

Abstract: In an optical line tracer sudden changes of velocity can cause instability and vibration. Means are provided to limit acceleration or deceleration to a specific rate of change. Speed change signals are processed through a ramp circuit which converts the step function signal to a ramp function before application.

Abstract: In a circular scanning pattern tracing system, a dual scanning pattern is provided to detect pattern changes in advance of the system steering axis. Pattern detection pulses from both the scanning patterns are adjustable in length and the overlap of the pulses is used to determine whether the system should slow down.

Abstract: In a circular scanning pattern tracing system having a sample and hold circuit, the width of the sample pulse is made adjustable. This variable width is equivalent to a variable low pass filter in the system. The effective cut off frequency of the filter is made dependent on the system tangential tracing velocity.

Abstract: An optical pattern follower uses a photo matrix to scan a pattern. The scan pattern is determined by generating a series of point addresses storing such addresses and interrogating the matrix only when the point address in the matrix being scanned corresponds to an address in the store. The resulting signals are processed to produce direction velocity signals which cause the follower to follow the pattern at a predetermined tangential velocity.

Abstract: This invention relates to a flexible notch filter for use in a servo system to eliminate natural mechanical resonance. The filter is an improved "twin-T" type where the "in-phase" output of the filter is fed back into the filter. Varying the feedback varies the bandwidth of the filter. The improved filter further provides for attenuation control in addition to control of the center frequency of the filter. The advantage of this filter over prior art designs is that one filter may be manufactured and adapted to be used in many servo systems since the filter can be easily adjusted to effectively eliminate the natural resonating frequency of the machine in addition to reducing phase lag at frequencies below the center frequency of the notch filter.

Abstract: A circular scanning optical pattern tracer produces two impulses per cycle, one impulse in the forward direction and one in the reverse. Means are provided to utilize either one of said impulses selectively to cause the tracer to proceed in a given direction or reverse at will in accordance with the pulse selected.

Abstract: This invention relates to the protection of power transistors in an H configuration power amplifier which drives a D.C. motor. When the amplifier is switched off, it may be possible for the base terminals of the transistors to be turned "on" which results in the transistors conducting. If two series transistors conduct, the resulting short circuit may damage or destroy the transistors. This invention provides an easy and economical apparatus for protecting the transistors in the power amplifier by grounding the base input terminals of the power transistors during all times when the transistors are switched "off.