akbarza
Full Member level 2
Schmitt trigger thershold in a circuit
hi
from site: **broken link removed**
the subject is about schmitt trigger threshold. with looking the image( that i attached it), the below text is written:
The above diagram reproduces the basic Schmitt trigger circuit of Richard Piotter. It consist of two inverters (NPN and PNP) which give a double inversion to the input signal. The output of the second stage is fed back and summed with the input signal and a resistor to ground. Think of those resistors as forming a voltage divider which determines the input voltage required to cross the 0.6 V threshold of the NPN base emitter junction to turn the transistor on of off. With the values given the positive going threshold is 1.95 V and the negative going threshold is 1.34 V assuming a Vcc of 5V. The output signal at the PNP collector is non-inverting with respect to the input signal.
please explain to me how the values 1.95v and 1.34 are obtained?(the value of right -below resistor is 47 k)
thanks
hi
from site: **broken link removed**
the subject is about schmitt trigger threshold. with looking the image( that i attached it), the below text is written:
The above diagram reproduces the basic Schmitt trigger circuit of Richard Piotter. It consist of two inverters (NPN and PNP) which give a double inversion to the input signal. The output of the second stage is fed back and summed with the input signal and a resistor to ground. Think of those resistors as forming a voltage divider which determines the input voltage required to cross the 0.6 V threshold of the NPN base emitter junction to turn the transistor on of off. With the values given the positive going threshold is 1.95 V and the negative going threshold is 1.34 V assuming a Vcc of 5V. The output signal at the PNP collector is non-inverting with respect to the input signal.
please explain to me how the values 1.95v and 1.34 are obtained?(the value of right -below resistor is 47 k)
thanks