Informações sobre o equipamento:
|Conar Coletronics Service Inc. 255 Osciloscópio|
Conar Coletronics Service Inc.
|Categoria:||Instrumentos de medição|
The circuitry of the Model 255 oscilloscope can be divided into four sections: the vertical amplifier, the horizontal amplifier, the sweep generator, and the power supply. Refer to the block diagram, Fig. 45, for the following general description of how these sections fit together to form the complete oscilloscope. The vertical amplifier receives the signal to be observed by the oscilloscope, amplifies this signal by the setting of the VOLTS/CM switch on the front panel, and applies the signal, in push-pull form, to the vertical deflection plates of the cathode ray tube (crt). A sample of the vertical signal is also made available to the sweep section for triggering. The vertical amplifier includes controls for ac or dc coupling, vernier adjustment of gain, and vertical positioning of the trace on the crt screen. This section of the oscilloscope features high gain and wide bandwidth. The horizontal amplifier is very similar to the vertical amplifier, but the circuit is somewhat simplified because of the relaxed gain and bandwidth requirements. This section of the oscilloscope must take a sweep signal, which may be generated by the sweep circuit or by an external source, amplify this signal, and apply it, again in push-pull form, to the horizontal deflection plates of the crt. The horizontal amplifier includes controls for selection of its signal source and for horizontal placement of the trace on the crt screen. The Horizontal/ Trigger (H/T) Gain control on the front panel affects the level of only the external horizontal or trigger signal; it does not vary the width of the trace in the internal or line sweep modes. The external sweep input is ac coupled, but the horizontal amplifier itself is direct-coupled to the output of the sweep circuit for best performance at very low sweep rates. The sweep generator section can be considered as three subsections: the trigger generator, sawtooth generator, and blanking subsections. The function of the trigger generator is to convert the trigger input signal into a pulse suitable for application to the sawtooth generator circuit. The triggering level is adjusted with a front panel control. The front panel Trigger Slope switch selects whether the trigger occurs on the positive-going or the negative-going portion of the applied signal. The purpose of the sawtooth generator is to generate a high-linearity sawtooth waveform for application to the horizontal amplifier. The sawtooth generator in the Model 255 is a triggered sweep; that is, it operates only when it is told to do so. The command to sweep comes from the trigger generator. Once a sweep is initiated, the sawtooth generator will ignore all further trigger pulses until the sweep and its retrace are completed. What this means to you, the user of the oscilloscope, is that the sweep is highly stable and is not affected by changes in input frequency. The use of a triggered sweep also allows horizontal expansion of the signal to a degree not possible with conventional recurrent sweep generators. At the end of each sweep, during the time that the sweep output voltage is rapidly falling toward its originating point, the blanking amplifier applies a large negative-going pulse to the grid of the crt. This causes the beam to cut off and light output from the crt to cease. Since this happens while the electron beam is being swept back to the left side of the screen for the next sweep, the retrace line is effectively blanked. The power supply section of the oscilloscope supplies all operating voltages to the other three sections. The high voltage supply develops -2000 volts for the crt electron gun, +220 volts for the vertical and horizontal output amplifiers and the blanking amplifier, 6.3 volts ac for the crt heater, and develops a regulated +5 and - 5 volts for all other oscilloscope circuitry. In addition, one of the transformer windings also supplies a small ac voltage for use in the line sweep and line trigger modes. Now that you are familiar with the overall operation of the various sections of the oscilloscope, refer to the complete schematic diagram on the separate insert sheet as we begin the detailed circuit description. You will start with the vertical amplifier.
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|Conar Coletronics Service Inc. -- 255 -- Manual de serviço|
|O nome do arquivo:||Conar-9185.pdf|
|Tipo manual:||Manual de serviço|
|Tamanho:||2.94 Mbytes (3086077 Bytes)|
|Qualidade:||Documento Scaned, a leitura parcialmente mal, não parcialmente legível.|
|Envie data:||05 Agosto 2017|
|Downloads:||29 desde 05 Agosto 2017|
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