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BC, BC, BC High Current Transistors NPN Silicon Features. Base NPN Epitaxial Silicon Transistor Absolute Maximum Ratings Ta=25 C unless otherwise noted Symbol Parameter Value Units VCER Collector-Emitter Voltage at RBE=1K? : BC 45 V: BC 60 V: BC V. BC BC VCEO. Vdc. Collector – Base Voltage. BC BC BC VCBO dimensions section on page 4 of this data sheet. ORDERING. DATA SHEET. Product specification. Supersedes data of Apr Oct DISCRETE SEMICONDUCTORS. BC; BC; BC

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I assumed that’s what he had in the junkbin.

A forced beta of 20 is usually datashete. This is perhaps the easiest to understand, because it’s as intuitive as the common emitter switch, but you only have to calculate the load resistor.

Common emitter switch This is the traditional “Transistor-as-a-switch” configuration, and is similar to what you have right now. If you want to pass at most 20 mA through the collector, aim for 2 mA through the base, and you end up with a base resistor of about 2. It would be awesome if we could, it would make many circuits simpler, but it’s simply too unreliable to be of any practical use. You calculate the resistor value bcc637 looking up the voltage drop across the LED for the current you want, then observing that the voltage drop across the resistor will be the datssheet from the Arduino pin minus 0.

Just to be clear, your suggested circuit will put way too much current through the LED, and it will be poorly controlled. The transistor will draw the absolute minimum amount bc37 base current necessary to keep the right amount of current flowing through the collector.

transistors – BC as switch with Arduino – Electrical Engineering Stack Exchange

Look at this spread from the datasheet:. Emitter follower This can be seen as a current booster. As you can see, there is no base resistor. This can be seen as a current booster. Datadheet little warning however: I’d sure like to see the documentation that claims this is the recommended value.


ChetanBhargava He’s reading the minimum hFE, it goes up to If the 5V rail drops before the power to the Arduino, perhaps if they are powered from separate rails, all the current to the LED will come b637 the base, and thus from the Arduino.

Essentially you’ll use one of these circuits:. Sign up or log in Sign up using Google. I’m glad you’ve done the calculations, that’s a good start. This is datahseet the way to do it.

Post Your Answer Discard By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies. Look at this spread from the datasheet: The voltage V CEbetween the collector and emitter, is called the saturation voltage and is usually small enough to be neglected. The goal is to drive enough current datahseet the base to make this happen.

The datasheet for the BC shows it as less than mV up to a collector current of mA. The voltage at the emitter will closely track the voltage at the base, only 0. Thank you for the explanation, well i’m student in the area so i lack the expertise.

BC637 Datasheet

The gain of the transistor is not well defined probably between 80 and If your board has an unregulated input with a lot of ripple, you can use it directly. Rodrigo Peetz 10 3. Will it work the way I planned? That’s how I select transistors. Post as a guest Name. Essentially you’ll use one of these circuits: Email Required, but never shown. Essentially I stopped reading there.



There must be hundreds, thousands of instructions out there on how to drive a LED with an Arduino, and the best method will be slightly different depending on the voltage drop across your LED. This is a classic mistake. RodrigoPeetz Yes, no one will blame you or think less of you for assuming that you can use the transistor in the way you wanted.

ChetanBhargava i salvaged this from one circuit and its laying in my bin. Then you pick a base resistor to make sure the transistor is saturated.

BC – BC NPN High Current Transistor

The voltage at the collector does not have any say in the current through the LED, which is another benefit. Home Questions Tags Users Unanswered. Why not add 3 common emitter switch? I don’t have much experience with electronic components, and I would like to ask someone with more datsheet than me to check if my calculation is correct.

(PDF) BC637 Datasheet download

It is better dafasheet add a series resistor on the LED – the forward voltage of a blue LED is probably around 3V, so the resistor drops 2V and at 22mA it would have to be about 91 ohms. It seemed superfluous at the time, but it makes a better answer. This works if the voltage drop across the LED is small enough that you have some “headroom” left across the resistor.

This is no omission from my part, and it is one of the benefits of this configuration: MOSFET switch This is perhaps the easiest to understand, because it’s as intuitive as the common emitter switch, but you only have to calculate the load resistor.