Direct Coupled Oscillograph Amplifier

Progress in the field of direct-inking oscillographs has made the development of a d-c amplifier very desirable. This paper describes the circuits used to obtain the characteristics desired in a d-c amplifier when it is used with a direct-inking oscillograph. The combination of these circuits resulted in the development of a direct coupled amplifier which is operated entirely from an a-c source. The amplifier has a very low drift rate and, mechanically, is readily portable. The performance of the direct-inking oscillograph and d-c amplifier is illustrated with chart records showing recordings of d-c pulsations and sine waves. The treatment of the subject matter is concluded with a description of an industrial application in the use of the oscillograph with a d-c amplifier.