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The magazine was considered a lot of different devices preheating of the cathodes of the picture tube to the high voltage supply on anode. Almost all of the previously described devices after this warm-up restores factory default settings enable the filament. However, in my opinion, not take into account that when filament voltage is above the nominal (6.3 V) at least 0,2...0,3 V, the lifetime of the tube is greatly reduced.

Not coincidentally, the overestimation of the voltage is considered to be the main cause of the output tubes out of action until the warranty period expires. Therefore, it is necessary to strictly control the value of the voltage supplied to the filament. Given that the shape of the filament current the CRT is far from sinusoidal, ordinary voltmeters to measure in such case do not fit.

For this purpose, I propose a simple attachment to any the ohmmeter which can measure the RMS voltage of any shape with quite sufficient accuracy.

Schematic diagram of the device shown in the illustration. OPTRON EIA-13 replace the CES-9 - EIA-12. The resistor R1 is selected so that the input voltage optocouplers did not exceed the certified value, in our case it is equal to 5.8 V.

The console is calibrated with the constant flow stabilized voltage to the input with simultaneous measurement of the output resistance of the optocoupler. In case use the console to control only the filament voltage of the kinescope her it helps to calibrate at one point (6,3 In).

Author: C. gemkow, Oktyabrsky, Bashkortostan