Signalling circuit arrangement for comparing two alternating voltages

摘要

The signalling circuit arrangement for comparing constant or simultaneously changing amplitudes or phase lengths of two alternating voltages has two threshold value switches (SW1; SW2) which convert the alternating voltages (U1; U2) into square-wave voltages (Us1; Us2) and which are connected on the output side to one transformer (Tr1, Tr2) each. The secondary sides, having opposite directions of winding, of the transformers are each connected via a resistor (R20 and R22) to the base of a transistor (T5; T6) and at the other end in each case to a pole of a direct voltage source. The transistors are connected in series with a capacitor (C1) which is located in an oscillatory circuit, the capacitor being arranged between the transistors. At the output of the oscillatory circuit, a display and evaluation device is provided which only receives a signal if the negative edge of the square-wave voltage is to be compared, and thus the amplitutes of the alternating voltages to be compared, lie within a predetermined tolerance range. <IMAGE>