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The company was acquired by ON Semiconductor in 2016 and its products and technologies continue to be developed and sold under the ON Semiconductor brand. The company was known for its innovation in the development of the first commercial transistor and for its contributions to the advancement of the integrated circuit technology.įairchild became a leading supplier of power semiconductors, analog and mixed-signal integrated circuits, and other semiconductor products. Secondly, change the current limiting resistors R7- R18 from 75Ω to 180Ω.Fairchild Semiconductor was a pioneering semiconductor company that was founded in the late 1950s.

First, three LEDs are to be limited to just 2 LEDs. In this case, two replacement is necessary. However, this circuit does operate at a 9V battery. It can be used in televisions, we can use it in home appliances, can be used as a small load switch, it can also be used as an amplifier. It comes in the TO-92 package and used in a wide range of applications. This circuit operates at 12V of DC power supply. 2N3904 is NPN Bipolar Junction Transistor designed for switching purposes at 100mA and as an amplifier at 100MHz frequency. Once, transistor Q3 is set ON, the 12 transistor drives the LEDs according to the signal sent by diodes. The third part of the circuit consisting of transistors Q4 to Q15 connected with LED depends entirely upon the ON/OFF signal from transistor Q3. This DC signal enters the base of transistor Q3 and thus, activates it. After the 10♟ electrolytic capacitor filters the amplified electrical signal, diodes D1, and D2 rectify it into a DC signal. Now, this amplified signal goes through the filtering and rectification part. Furthermore, the sensitivity can also be decreased by replacing the variable resistor of 100KΩ with 200KΩ or 300KΩ. Moreover, the sensitivity of the overall circuit is adjusted through the 100KΩ potentiometer. This electrical audio signal is then amplified by the transistors Q1 and Q2. Electret microphone catches the sound from the surroundings and converts it into an electrical signal. The main part of the circuit is the transistors Q1, Q2, and Q3 that are accountable for sound detection and amplification. Here, the project consists of 36 LEDs, 15 transistors, and a combination of resistor and capacitor.

2n3904 pinout download