The 2N3904 is a common NPN bipolar junction transistor used for general-purpose low-power amplifying or switching applications.

Circuit 8: The non-inverting circuit uses a pair of complementary NPN type ( 2N3904) and PNP type (2N3906) transistors.

Circuit 7: How to design a 13.56mhz sine wave power amplifier circuit with 2N3904.Circuit 6: 2N3904 Sample Circuit-Amplifier.CatalogĬircuit 1: Thermostat controller composed of LM75 intelligent temperature sensor and 2N3904 transisitor Hope these circuit diagrams are helpful to you. These circuit diagrams are basically beginner-friendly types. Due to this biasing current, 2N3904 goes to the saturation state and the LED turns ON.In this blog, Apogeeweb has prepared 8 simple 2N3904 circuits for electronics enthusiasts. When the switch is closed, the base of the transistor is biased, and current flows to the base of the transistor. Due to this, 2N3904 remains in the cut-off state and the LED does not glow.

And no current flows to the base of the transistor.

When the switch is open, the base of the transistor is not biased. The required resistor value can be easily calculated using Ohm’s law. Proper biasing of the base ensures adequate base current to turn ON the transistor.Ī resistor of 220 Ohm is connected between the load(LED) and the collector terminal to protect the LED from overcurrent. The base of the transistor is biased using a 10 K Ohm resistor(R3) in parallel to the 1 K Ohm resistor(R2) plus base-emitter junction resistance(in series). The complete circuit is powered via a 5 V supply. In the circuit diagram given above, 2N3904 is used as a switch to turn ON/OFF an LED connected at the collector terminal.

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