TRIGGERED SWEEP UNIT FOR ELECTRONIC OSCILLOSCOPES OF THE OK-17M AND EO-7 TYPES

V. M. RAZIN

(Presented by the scientific seminar of the Faculty of Physics and Engineering)

The two-beam electronic oscilloscope of the OK-17M type is intended only for observing single electrical pulses. In order to make it possible to observe periodic pulses in studying processes associated with the injection and dumping of electrons in a betatron, the author developed a unit for periodic triggered sweep. The introduction of a small number of additional elements made it possible to adapt this circuit also for operation with the single-beam electronic oscilloscope of the EO-7 type. The schematic diagram of the unit is shown in Fig. 1.

The generator of control internal triggering pulses on tube Л1 is a symmetrical multivibrator, whose oscillation frequency is rigidly synchronized with the line frequency by applying the AC line voltage to one of the grids of the multivibrator. The generator is switched on and off by toggle switch Р. Pulses from the internal source on tube Л1, or from an external source from terminal 1, trigger the cathode-coupled triggering circuit on tube Л2. The polarity of the internal triggering pulses is negative; that of the external pulses is positive. The stage on tube Л2 produces positive rectangular voltage pulses of duration 100 μsec and of sufficiently large amplitude (over 250 V).

These pulses are applied to the grids of cathode followers on tubes Л3 and Л4. The cathode follower on tube Л3 has a dual purpose. Directly from the cathode of tube Л3, through coupling capacitor C6 (terminal 2), the pulses are to be applied, for triggering the sweep of the OK-17M oscilloscope, to the cathode of thyratron Л12. It should be noted that no alterations in the circuit of the OK-17M oscilloscope are required. It is only necessary to bring out a lead from the cathode of thyratron Л12 (see the description and instructions for the OK-17M).

From potentiometer R14 (terminal 3), when working with the EO-7 oscilloscope, the pulses are applied to the “brightness modulator” terminal. From the output of the cathode follower on tube Л4 (terminal 4), positive pulses can be used to trigger thyratrons in pulse circuits of the betatron.

The unit contains a calibrator for the time-sweep scale. The calibrator is a shock-excitation generator [1] on tube Л6 with an oscillation frequency of the circuit of 500 kHz.

positive pulses from the cathode follower on tube \(L3\) are fed to the grid of tube \(L5\) through the limiting resistance \(R_{19}\). The capacitance \(C_5\) is intended to reduce the duration of the leading edge of the voltage pulse on the grid of tube \(L5\). From the anode of tube \(L5\), negative voltage pulses with a steep leading edge are fed to the grid of the shock-excitation generator, bringing the latter into an excited state.

Fig. 1

Sinusoidal oscillations from the output of the calibrator are fed to the grid of the cathode follower on the second half of tube \(L5\). From the output of the cathode follower (terminal 6), the calibration voltage can be applied to one of the amplifiers of the OK-17M oscilloscope or to the “vertical” amplifier of the EO-7 oscilloscope for calibration of the time scale.

When working with the EO-7 oscilloscope, the sweep voltage to the “horizontal” amplifier may be supplied from the anode of tube \(L6\) through the coupling capacitor \(C13\) (terminal 5). In conclusion, we note that with this accessory it is possible to investigate periodic processes with a pulse duration of no more than \(100\ \mu\text{s}\). This is quite sufficient for studying processes during the injection and displacement of electrons in a betatron.

References

1. L. A. Mesrovich, L. G. Zelichenko. Pulse Technique. Sovetskoe Radio, 1953.