The article discusses the problem of transformation of measuring signal of differential transformer converter of universal testing machines for further processing by microprocessor controller. In order to automate the testing process, it is necessary to collect, process and transmit the measured data to an automated workplace using a microprocessor controller. Due to the fact that usually the secondary windings of the differential transformer converters produce an alternating voltage of very small magnitude, such a measurement signal cannot be processed with the help of modern microprocessor controllers without conversion. Since the analog-to-digital converter of the microprocessor controller cannot operate with alternating voltage, it becomes necessary to rectify and amplify the measuring signal. For low voltages (less than 0.6 V), the use of conventional resistor-diode rectifiers becomes impossible and there is a need for other methods of rectifying alternating current. It is proposed to use full-wave active rectifiers without diodes on operational amplifiers for conversion of the measuring signal of differential transformer converters, the main disadvantages of diode rectifiers and advantages of rectifiers on operational amplifiers are considered. The biggest advantage of a rectifier proposed for use in an automated testing system is the ability to simultaneously rectify and amplify the measurement signal with the required precision, allowing it to be processed by most modern microprocessor controllers. For the first time, an automated testing system on a tensile machine was developed using an active full-wave voltage rectifier on operational amplifiers without the use of diodes. The circuit shown in the article makes it possible to convert the signal of a differential transformer converter for further processing using the Arduino microcontroller platform. An amplifying active full-wave voltage rectifier without diodes on operational amplifiers can be used to modernize testing or measurement equipment containing a differential transformer transducer of a measuring signal. The developed electrical circuit of the rectifier was applied to automate the process of testing on the breaking machine of model P-0.5. Keywords: differential transformer converter, operational amplifier, rectifier, measuring signal converter, tensile testing machine, automated test system.
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