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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Home Questions Tags Users Unanswered. This is a classic mistake.

## BC637 Datasheet

ChetanBhargava He’s reading the minimum hFE, it goes up to I’m glad you’ve done the calculations, that’s a good start. Common emitter switch This is the traditional “Transistor-as-a-switch” configuration, and is similar to what you have right now.

Why not add 3 common emitter switch? So using the formula: Then you pick a base resistor b637 make sure the transistor is saturated.

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

The datashwet at the collector does not have any say in the current through the LED, which is another benefit. The gain of the transistor is not well defined probably between datasbeet and I assumed that’s what he had in the junkbin. Hc637 your board has an unregulated input with a lot of ripple, you can use it directly. A little warning however: The datasheet for the BC shows it as less than mV up to a collector current of mA.

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. I’d sure like to see the documentation that claims this is the recommended value.

I don’t have much experience with electronic components, and I would like to ask someone with more experience than me to check if my calculation is correct.

You calculate the resistor value by 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 voltage from the Arduino pin minus 0. 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.

Email Required, but never shown. Sign up or log in Sign up using Google. Post as a guest Name. Look at this spread from the datasheet:.

A forced beta of 20 is usually good. Datashet conservative number is one tenth of the current through the collector. Essentially you’ll use one of these circuits:. ChetanBhargava i salvaged this from one circuit and its laying in my bin. Essentially you’ll use one of these circuits: Datashdet 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.

Rodrigo Peetz 10 3.

As you can see, there is no base resistor. A circuit that relies on a specific current gain will simply not work well. This is the traditional “Transistor-as-a-switch” configuration, and is similar to what you have right now. Just to be clear, your suggested circuit will put way too much current through the LED, and it will be poorly controlled.

### BC – BC NPN High Current Transistor

The current gain varies a lot depending on all sorts of things: 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. That’s how I select transistors. It seemed superfluous at the time, but it makes a better answer. 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.

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.

Sign up using Facebook. 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. Is my calculation correct? If the 5V rail drops before the power to the Arduino, perhaps if they are powered from separate rails, all the current bc6637 the LED will come from the base, and thus from the Arduino. Will it work the way I planned? This is no omission from my part, and it is one of the benefits of this configuration: 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.