Variable frequency control circuit

Claim 2

A control circuit for providing drive pulses of variable frequency and constant pulsewidth from a D.C. power source to a load comprising variable frequency pulse generator means operative to provide output pulses of a selected frequency and drive pulse switching means connected to receive said output pulses and operative in response thereto to pass drive pulses of constant pulse width through said load from said D.C. power source, said pulse switching means operating to vary the frequency of said drive pulses in response to variations in the frequency of said output pulses.

Claim 3

The control circuit of claim 1 wherein said variable frequency pulse generator means includes a capacitor, a variable charging circuit connected between said D.C. source and said capacitor for charging said capacitor at a preselected rate, and semiconductor means connected to fire and provide an output pulse when said capacitor reaches a determined charging point, and capacitor discharge means connected to said capacitor and to said drive pulse switching means, said capacitor discharge means being operative by said drive pulse switching means upon receipt thereby of an output pulse to discharge said capacitor.

Claim 4

The control circuit of claim 1 wherein said drive pulse switching means includes a monostable multivibrator having first transistor means connected to receive said output pulses, said first transistor means being rendered conductive upon receipt thereby of an output pulse, second transistor means connected to be rendered conductive upon conduction of said first transistor means, and multivibrator capacitor means connected between said first and second transistor means and operative upon conduction of said second transistor means to charge to increase the conduction of transistor means, said multivibrator capacitor means operating upon reaching a determined charge to decrease the conduction of said first transistor means until termination of conduction thereby.

Claim 5

The control circuit of claim 3 wherein a multivibrator capacitor discharge means is connected to said multivibrator capacitor means, said second transistor means being operated by the decrease in conduction of said first capacitor means to decrease conduction of said second transistor means until termination of conduction thereof, said second transistor means operating subsequent to the initiation of decreased conduction therethrough to cause said multivibrator capacitor to discharge through said multivibrator capacitor discharge means.

Claim 6

The control circuit of claim 4 wherein said multivibrator capacitor discharge means includes diode means operative to discharge said multivibrator capacitor means to a set discharge level.

Claim 7

The control circuit of claim 4 wherein said second transistor means operates to reverse bias said multivibrator capacitor means to rapidly discharge said multivibrator capacitor means through saId multivibrator capacitor discharge means.

Claim 8

The control circuit of claim 6 wherein said variable frequency pulse generator means includes a capacitor, a variable charging circuit connected between said D.C. source and said capacitor for charging said capacitor at a preselected rate, and semiconductor means connected to fire and provide an output pulse when said capacitor reaches a determined charging point, and capacitor discharge means connected to said capacitor and to said drive pulse switching means, said capacitor discharge means being operative by said drive pulse switching means upon receipt thereby of an output pulse to discharge said capacitor.

Claim 9

The control circuit of claim 7 wherein said variable charging circuit includes a logarithmic potentiometer

Claim 10

The control circuit of claim 7 wherein said capacitor discharge means includes a diode having an anode connected to said capacitor and a cathode connected to said second transistor means, said diode being biased into conduction upon the conduction of said second transistor means.