Automatic identifier circuit for two different color television standards, intended for the switching of video converter stages corresponding to one or another transmission system, essentially characterized by consisting of an input amplifier stage constituted by a transistor to whose base is applied, in addition to the input signals picked up by the antenna, the wave trains at the frequency of 3.9 megahertz, existing in the frame erase periods of the signals themselves, when the receiver captures information encoded in the secam standard, polarizing said impulses the base of the transistor by means of a voltage divider constituted by two resistors mounted respectively between base and ground and between base and signal input, while the collector circuit of the transistor itself is coupled to the tuned primary of a high frequency transformer, in which are obtained the impulses suitably amplified and from whose secondary is a detection of the signals by means of a diode in series and another in derivation and an integration of those by means of a filter constituted by two capacitors in derivation and a resistance, obtaining a wave in the shape of sawtooth whose period has a duration of 20 milliseconds (Machine-translation by Google Translate, not legally binding)
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