Single Transistor Inverted Schmitt Trigger
Category: Transistor Logic
Designer: RANA MUHAMMAD ADNAN KHALIL
Notes
The circuit is simulated in Proteus. You can simulate this circuit in any other simulation software like LTspice or Psim. This is a very simple circuit and a very basic concept of schmitt trigger. 1. To understand this circuit, you should know how transistor acts as an inverter. 2. Very few components needed to build this circuit. A transistor and three resistors only. 3. Random input signal is applied at resistor R1. 4. Output is taken from transistor Q1 collector point. 5. On oscilloscope, yellow wave shows output and blue wave shows input which is random signal. 6. This circuit will act as a comparator with hysteresis whose thresholds for setting the output high or low will be defined by the design parameters. 7. The value of thresholds depends on voltage across resistor R3 plus transistor base emitter voltage, which is 0.7V. 8. This value can be changed by changing the value of resistor R3. 9. The working of the circuit is seen in the waveform, which is perfectly fine but inverted. The waveform can be non-inverted by applying another transistor at output. Next circuit will show non-inverted schmitt trigger.