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hfe is a multiplier not measured in mA. Corrected 500 ohm example to nearest standard size.
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edit approved Oct 17, 2021 at 18:19
Nick
edit approved Oct 17, 2021 at 18:19
Nick
  • 113
  • 4

  1. Yes

  2. Yes. You can calculate the resistor by calculating base required current (you will need to know 'hfe' of your transistor). But you can just try. Working range is quite high, so if you will just use 500510 Ohm for example, it should just work.

    For example, if max total current is 100mA, voltage is 5V, and hfe is 150mA150, you need 100mA / 150mA150 = 0.6mA base current, so resistor should be 5V / 0.0006 = 8.3kOhm or less.

  3. There are lots of differences, but yes, it depends on how much current you will need in the worst case. If these LEDs are usual 10mA ones, almost any BJT will work so you can take what's cheaper or what you already have.

BTW. Don't see your shift register :-)

  1. Yes

  2. Yes. You can calculate the resistor by calculating base required current (you will need to know 'hfe' of your transistor). But you can just try. Working range is quite high, so if you will just use 500 Ohm for example, it should just work.

    For example, if max total current is 100mA, voltage is 5V, and hfe is 150mA, you need 100mA / 150mA = 0.6mA base current, so resistor should be 5V / 0.0006 = 8.3kOhm or less.

  3. There are lots of differences, but yes, it depends on how much current you will need in the worst case. If these LEDs are usual 10mA ones, almost any BJT will work so you can take what's cheaper or what you already have.

BTW. Don't see your shift register :-)

  1. Yes

  2. Yes. You can calculate the resistor by calculating base required current (you will need to know 'hfe' of your transistor). But you can just try. Working range is quite high, so if you will just use 510 Ohm for example, it should just work.

    For example, if max total current is 100mA, voltage is 5V, and hfe is 150, you need 100mA / 150 = 0.6mA base current, so resistor should be 5V / 0.0006 = 8.3kOhm or less.

  3. There are lots of differences, but yes, it depends on how much current you will need in the worst case. If these LEDs are usual 10mA ones, almost any BJT will work so you can take what's cheaper or what you already have.

BTW. Don't see your shift register :-)

indentation and grammar, and additional minor things to get to 6 characters… (sigh)
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edit approved Jan 7, 2016 at 8:45
poke
edit approved Jan 7, 2016 at 8:45
poke
  • 165
  • 1
  • 4
  • 12

  1. Yes

  2. Yes. You can calculate the resistor by calculating base required current (you will need to know 'hfe' of your transistor). But you can just try. Working range is quite high, so if you will just use 500 Ohm for example, it should just work.

    For example, if max total current is 100mA, voltage is 5V, and hfe is 150mA, you need 100mA / 150mA = 0.6mA base current, so resistor should be 5V / 0.0006 = 8.3kOhm or less.

  3. There are lots of differences, but yes, it depends on how much current you will need in the worst case. If these LEDs are usual 10mA ones, almost any BJT will work so you can take what's cheaper or what you already have.

For example, if max total current is 100mA, voltage is 5V, and hfe is 150, you need 100/150 = 0.6mA base current, so resistor should be 5V/0.0006 = 8.3kOhm or less.

  1. There are lots of difference, but yes, it's depend on how much current you will need in the worst case. If these LED's are usual 10mA ones, almost any BJT will work so you can take what's cheaper or what you already have.

BTW. Don't see your shift register :-)

  1. Yes

  2. Yes. You can calculate the resistor by calculating base required current (you will need to know 'hfe' of your transistor). But you can just try. Working range is quite high, so if you will just use 500 Ohm for example, it should just work.

For example, if max total current is 100mA, voltage is 5V, and hfe is 150, you need 100/150 = 0.6mA base current, so resistor should be 5V/0.0006 = 8.3kOhm or less.

  1. There are lots of difference, but yes, it's depend on how much current you will need in the worst case. If these LED's are usual 10mA ones, almost any BJT will work so you can take what's cheaper or what you already have.

BTW. Don't see your shift register :-)

  1. Yes

  2. Yes. You can calculate the resistor by calculating base required current (you will need to know 'hfe' of your transistor). But you can just try. Working range is quite high, so if you will just use 500 Ohm for example, it should just work.

    For example, if max total current is 100mA, voltage is 5V, and hfe is 150mA, you need 100mA / 150mA = 0.6mA base current, so resistor should be 5V / 0.0006 = 8.3kOhm or less.

  3. There are lots of differences, but yes, it depends on how much current you will need in the worst case. If these LEDs are usual 10mA ones, almost any BJT will work so you can take what's cheaper or what you already have.

BTW. Don't see your shift register :-)

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BarsMonster
BarsMonster
  • 3.2k
  • 5
  • 49
  • 81

  1. Yes

  2. Yes. You can calculate the resistor by calculating base required current (you will need to know 'hfe' of your transistor). But you can just try. Working range is quite high, so if you will just use 500 Ohm for example, it should just work.

For example, if max total current is 100mA, voltage is 5V, and hfe is 150, you need 100/150 = 0.6mA base current, so resistor should be 5V/0.0006 = 8.3kOhm or less.

  1. There are lots of difference, but yes, it's depend on how much current you will need in the worst case. If these LED's are usual 10mA ones, almost any BJT will work so you can take what's cheaper or what you already have.

BTW. Don't see your shift register :-)