| 摘要 |
A circuit for actuating control elements, for example a fuel shutoff valve in the carburetor of an internal combustion engine or a similar control element. The circuit is responsive to engine speed and to throttle valve position as monitored via the intake manifold vacuum. When the engine idles and the throttle is closed, the fuel control valve is held open to supply normal idling fuel or fuel mixture. However, if the engine speed rises above a threshold speed while the throttle is closed, the control circuit assumes a condition of engine braking and the fuel supply is interrupted. The switching threshold is established as the voltage on a capacitor controlling a transistor, the capacitor being charged continuously and being discharged during the occurrence of voltage spikes taken from the ignition coil of the vehicle.
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