ELECTRICAL DEVICE UNIT FOR HIGH-FREQUENCY WELDING OF PLASTICS Russian patent published in 1994 - IPC

FIELD: plastic welding. SUBSTANCE: direct-current voltage source is made in the mentioned device with non-transformer input on the basis of unregulable semibridge of bridge semiconductor converter with a power pulse transformer and with a low-power saturable transformer in the feedback circuit. The radio-frequency oscillator is made as single-circuit transistorized LC - self-excited oscillator according to Hartley or Colpitts circuit at least with two power amplification stages and with the scheme of protection from misalignment overload. Besides, the latter is made as output resistive attenuator. The radio-frequency oscillator is provided with a thermal relay located in the zone of the oscillator maximum heating. The thermal relay is included in the control circuit of the oscillator supply. EFFECT: facilitated manufacture. 2 cl, 3 dwg