![]() ![]() I figured if the transistors burned out during this experiment, I could easily replace them (they were cheap) but I never needed to do that. So, I tried the approach without resistors and I was able to run the clock for hours without noticing any ill effects. And then I found someone else claiming they weren't needed because the resistors in the strip did all of the necessary work, and the output of the digital Arduino pins is only about 40 mA anyway at max (this transistor is rated for 200mA). I found others using 220 ohm resistors which brightens the display but still not matching the level of the unresisted setup. I used them and it dimmed my display (expected) but more than I was hoping. In many people's documentation regarding these transistors and LED strips with the Arduino, 1 Kohm resistors were mentioned and used. Do I really need the resistors between the Arduino output and the transistor base?ĭuring my first iteration of the project, I tried without them and it seemed to work just fine. Here's the big question, and I'm sorry if it sounds noobish. When I use this, and my code, I'm able to make a big impressive countdown clock. The 12v power supply is regulated before it makes its way to the Arduino using a 7805. The positive leads of the strips are connected to the 12v power supply. ![]() Each pin is connected to the (+) base of the transistors, whose (-) collectors are connected to ground and (-) emitters are connected to the negative leads of the strips. I'm using 2N3904 NPN transistors for each of the pins. I'm using all of the digital output pins to drive two custom seven-segment displays, constructed with 12v warm white LED strips. The project is a giant countdown clock, controlled by an Arduino UNO. Been stalking the forums here extensively recently but this is my first time posting.Įven though I've been working on hobby projects for a while and definitely understand the importance of resistors, I'm wondering if they're absolutely necessary in this case. The price for 2n3904 is 9rupess for 3pieces or 0.12USD dollars.Greetings all.The 2n3904 transistor is a low-power general purpose transistor, which had more applications at common appliances. ![]() Much higher circuit arrangements will be used at switching applications of the 2n3904 transistor.When the switch is closed the current starts to flow through the transistor base and it triggers ON and sent a signal to the LED.The 2n3904 is a low-power general purpose transistor, here we can see minimum component will be used to switch the LED using the 2n3904 transistor.The mini version of 2n3904 as a switch is the circuit above.Technically three-stage of amplification is done at this circuit to make an audio signal.As we can at the circuit both the 2n3904 transistor are connected back to back, that is the output signal from the Q2 transistor will pass towards the second transistor Q3.The amplification of the audio signal is done initially by the Q1 2sc1815 transistor, then the signal reaches the input of the 2n3904 transistor.The circuit consists of two 2n3904 transistors and 2sc1815 transistors. ![]() The figure shows the amplifier circuit using a 2n3904 transistor.In the table, we try to compare the electrical specifications of each of the transistors 2n3904 vs mpsa18, 2n3904 vs bc548, and 2n3904 vs 2n3906.Ģn3904 amplifier circuit 2n3904 amplifier circuit.The table below listed all the transistor devices similar to the 2n3904 transistor.The technical and physical aspects of all the transistors are the same.Each transistor in this list is NPN transistor equivalent for 2n3904.If you need the datasheet in pdf please click this link 2n3904 transistor Equivalent The maximum junction temperature on the 2n3904 transistor is 150☌.The noise figure of the 2n3904 transistor is 5dB.The transition frequency on this transistor is 300MHZ, it is an important factor in transistor switching applications.The power dissipation on the transistor is 625mW, this particular value indicates the power dissipation of this transistor device.The maximum collector current at 2n3904 transistor is 200mA, which means the maximum load current allowed on this transistor.The maximum current gain of this transistor will start from 30 to 300hFE, this gain value will be important at amplifier applications.The 2n3904 transistor is known as the general-purpose transistor device and technically they are designed to have low current and low power applications.If you need the datasheet in pdf please click this link 2n3904 Description ![]()
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