Frequency doubling circuit for automotive control system

For use in an automotive vehicle having electronic circuitry utilizing a-c information signals occurring at a frequency related to the angular velocity of a vehicle wheel, a pulse-generating circuit comprising:

• a sensor, positioned to provide frequency-indicating output signals varying in frequency as a function of variations in the angular velocity of the vehicle wheel;
• a differentiating circuit, connected to receive the frequency-indicating output signals and to produce both a positive-going signal and a negative-going signal during each complete cycle of the sensor output signal;
• a one-shot multivibrator circuit, including a first semiconductor switch having input, output and common connections and connected to be normally conducting, a capacitor coupled between the input and common connections of the first semiconductor switch such that upon discharge of said capacitor the switch is rendered non-conductive to generate a rectangular wave output pulse during the non-conductive period of the first semiconductor switch, and a resistor coupled to the capacitor to provide a path for charging the capacitor after each discharge to regulate the time duration of the rectangular wave output pulse from the one-shot circuit;
• a diode, having its anode coupled to the capacitor in the one-shot circuit and its cathode coupled to the differentiating circuit;
• and
• a second semiconductor switch, having input, output and common connections and having its output-common path coupled in parallel with said capacitor, and having its input connection coupled to the same point of the differentiating circuit as is the cathode of the diode, to complete a discharge path for said capacitor upon receipt of each positive-going signal from the differentiating circuit.