The circuit presented was found in a 1967 publication. It is a timer up to about 1 minute, triggering a relay that serves to control an external load. This circuit is feasible if the valve is obtained, since the transformer is common, serving only to power the filament. The time control is done in Rt which must have 4.7 M ohm or more. The time capacitor must have from 1 to 4.7 uF, it must be of the depolarized type for voltages of 200 V or more. The relay is high voltage (100 V or more) with 5 k ohm coil resistance. A sensitive direct current relay must be used.
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