Abstract: An anti-skid control system for vehicles wherein, in view of the fact that while it is desirable for a vehicle anti-skid control system to detect the speed of the vehicle body and the speed of the wheel to positively prevent the skidding of the vehicle, it is very difficult to detect the speed of the vehicle body, a plurality of control patterns for decreasing the wheel speed to prevent the locking of the wheels under an excessively large braking pressure are predetermined, whereby the selection among the control patterns is effected according to the conditions of the road surface detected by a vehicle body deceleration sensor and a reference wheel speed according to the selected control pattern is compared with the actual wheel speed to forcibly reduce the braking pressure when there is a tendency for the wheels to lock, thereby preventing the locking of the vehicle and hence the skidding of the vehicle without detecting the speed of the vehicle body.

Abstract: A combination of a linear integrated circuit supplied with voltages from a first dc voltage source and a second dc voltage source of lower power capacity and opposite polarity, a switching circuit for performing a switching action according to the output signal of the linear integrated circuit without consuming power from the low capacity dc voltage source, and a digital circuit operable by the reception of the switching signal from the switching circuit. The low level dc voltage source provides a voltage by converting the voltage supplied from the first dc voltage source.