DC isolating circuit for TDM transmission system - has dial triggered by capacitor and discharging capacitor through primary winding

摘要

The dc isolating circuit, for TDM transmission systems, avoids using an optoelectronic coupler and its associated relatively complex circuitry. The circuit includes one capacitor (1) a resistor (2) and an input trigger diode (3). The input trigger diode (3) is coupled in series with the primary winding of a transformer (4). This series combination is connected in parallel with the capacitor (1) charged over the resistor (2) from a 110V dc source. The trigger diode has bidirectional characteristics and can be eg a diac or antiparallel thyristors. The 110V applied to the input charges the capacitor. At a given point the capacitor voltage triggers the diode. The diode discharges the capacitor through the primary winding.