10/7/2023 0 Comments Transistor 2n3904![]() These transistors may come with straight or preformed leads.If you need a little beefier NPN transistor, look at our PN2222 which can support up to 600mA and if you need more than that, check out our TIP120 Darlington transistor which can handle up to 5A. Using two 100 ohm 1/4W resistors in parallel would be another approach. 2N3904 0. Power through the that resistor is P = 60mA * 3V = 180mW so a 1/4W resistor will work, though a 1/2W would be a better choice for long-term use. The example assumes an LED voltage drop of 2V, so R = (5V – Vled) / 60mA = 50 ohms. This value may vary a bit depending on what LEDs are being used. ![]() The 50 ohm resistor sets the overall current for the 3 LEDs. The 4.7K resistor on the base is there to limit the current out of the uC pin to safe levels and the value is not overly critical. This simple circuit allows you to drive all three LEDs off the same uC pin. 2N3904: 45Kb / 8P: NPN switching transistor 1999 Apr 23: KODENSHI KOREA CORP. You could use 3 pins on the uC to drive the 3 LEDs, but that is a waste of pins unless you have pins to spare. The 2N3904 is common general-purpose low-power NPN transistor used amplifying or switching applications. PINNING PIN DESCRIPTION 1 collector 2 base 3 emitter Fig.1 Simplified outline (TO-92 SOT54) and symbol. DESCRIPTION NPN switching transistor in a TO-92 SOT54 plastic package. The indicator consists of 3 LEDs which each draw 20mA of current.Ī uC pin can easily drive an LED at 20mA, but this circuit will require 60mA which is outside the range of the typical uC drive capability. NPN switching transistor 2N3904 FEATURES Low current (max. We have an LED indicator that we want to drive. NPN transistors are generally used in low-side switching applications where they are connected between the load and ground. These can be very handy when you need to boost the output of a uC pin to drive something that it can not drive directly. The 2N3904 is a common NPN BJT used in the applications of general-purpose switching or low-power amplifying applications. The 2N3904 are a good inexpensive general purpose NPN transistor for low power amplification and switching and should be part of every parts bin.
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