Sonar flasher speed control

DETAILED DESCRIPTION This and other objects are realized and the limitations of the prior art are overcome in this invention by utilizing the first electrical pulse, which is used to initiate the sonar pulse, to control a first and second transistor so as to discharge a capacitor each time the first pulse occurs.
The capacitor is charged through a series adjustable resistance, from a regulated voltage so that after each discharge of the capacitor the voltage builds up as an exponential ramp voltage as a function of time.
The ramp voltage is compared continuously with a fixed reference voltage, which is provided from a regulated voltage source.
Whenever the ramp voltage is greater than the reference voltage a second voltage pulse is generated by the comparator.
The duration of the second pulse is a function of the speed of the motor.
For example, if the motor slows down, so that the period between the pulses is lengthened, then the capacitor has a longer time to charge after each discharge so that the ramp voltage reaches a higher value of voltage.
Therefore, the time, during which the ramp voltage is greater than the reference voltage, is greater and the second pulses are of greater duration.
A transistor amplifier is provided in series with the motor, and an integrator circuit is provided between the voltage comparator and the power amplifier so that during the second voltage pulse the current to the motor increases.
Thus by varying the time duration of the second pulses, the speed of the motor can be adjusted.
The slower the motor speed the longer the duration of the second pulse and the longer time is available for the increased current to flow through the motor, so the motor speeds up.
On the other hand, when the motor speed is too fast, the second pulse is of shorter duration and therefore less current flows through the motor, causing it to slow down.
This feedback from the motor shaft serves to provide a control so as to maintain a constant speed.