The schmitt triggered connection of the transistors can be explained briefly as follows: If the voltage applied to the relays does not reach zero or the maximum value, the contacts will vibrate because the magnetism produced by the relay coil is insufficient. This situation is not desired at all in the relentless periods. Because the vibration causes the sparkle (spark) to cause the contact of the relay to deteriorate quickly. The transistors are connected in a triggered manner to minimize the oscillation of the relay contacts.
The Schmitt triggered turn-off time relay circuit operates as follows: T1 is the cut-off when C is still empty when energized. Therefore, the value of the voltage at the collector end of T1 (point A) is the maximum level according to the chassis. Therefore T2 immediately passes through the relay and the receiver runs. C, which starts to charge through R1 and pot, fills up after a while to transmit T1. When the voltage at the collector of the incoming T1 (A point) decreases, the voltage at the R3 resistor (B point), which is connected to the emitter, rises. This causes the T2 transistor ( due to two electrical effects ) to go through a rapid cut.
1. The tension in the collector of T1 falls and leads to the cutting of T2.
2. The voltage developed in the R5 resistor, to which the emitters of T1 and T2 are connected, acts to reduce the base current of T2. ( Negative feedback )
If it is pressed on the button B which is in the circuit, C will discharge, and T1 will be cut immediately. This causes the voltage at collector (point A) of T1 to rise, causing T2 to conduct. As a result, the schmitt triggering method allows the relay to transmit or intercept very quickly.