Abstract: A peak holding circuit comprises a capacitor for holding signal charges corresponding to a peak level of an input signal, and a current amplifier circuit comprising transistors connected in a triple darlington manner for supplying an output current corresponding to the held charges. An emitter of a transistor in the first stage out of the transistors connected in a darlington manner is connected to a collector of another transistor through which a collector cut-off current flows which is approximately equal to a collector cut-off current flowing through the transistor in the first stage. The other transistor has its emitter connected to ground. Therefore, the collector cut-off current flowing through the transistor in the first stage is cancelled, so that fluctuations in output current can be prevented even if a large reactive current is not allowed to flow through a transistor in the final stage out of the transistors connected in a darlington manner.

Abstract: A hydraulic brake system in which oil pressure control valves are respectively interposed between a master cylinder as well as an oil pressure source for generating a fixed oil pressure, and corresponding brakes. Each of the oil pressure control valves includes a valve casing having a first input port communicating with the master cylinder, a second input port communicating with the oil pressure source, an output port communicating with the corresponding brake, and an oil pressure chamber communicating with the output port. A spool is slidable fitted in a bore in the valve casing with a pressure receiving face at one end thereof confronted to the oil pressure chamber, for bringing the second input port and the oil pressure chamber into communciation on a side contracting the oil pressure chamber and for bringing the first input port and the oil pressure chamber into communication on a side expanding the oil pressure chamber.

Abstract: A locking device for a connector assembly wherein a completely fitted or locked condition of connectors thereof can be confirmed clearly at a glance by way of an electric circuit. One of the connectors to be fitted with each other by the above locking device is provided with a locking plate for movement between a locking position and a releasing position, a holding element for holding the locking plate at the locking position, and also a means for confirming the connector fitted condition comprising a short-circuiting element and a pair of short-circuiting terminals so as to be connected with each other for assembling electric connection between the short-circuiting terminals.