I am driving a blue led with a pnp transistor as schematic1.I am trying to bypass the transistor without removing it as schematic2.Is it OK?

schematic1 Schematic1 schematic2 Schematic2


1 Answer 1


Yes you can do like Schematic 2. The LED will light till the battery wears down.

  • \$\begingroup\$ What about the transistor? \$\endgroup\$ Commented Sep 19, 2017 at 1:08
  • \$\begingroup\$ If only one leg of the transistor is connected and the rest is hanging in the air it does nothing. You could clip it out if you wanted to. \$\endgroup\$ Commented Sep 19, 2017 at 1:16
  • \$\begingroup\$ When measuring voltage on emitter or base pin with multimeter,why am i reading voltage on these pins? \$\endgroup\$ Commented Sep 19, 2017 at 1:22
  • \$\begingroup\$ Because when you connect the meter to those parts that are hanging in mid air you are changing the circuit. Your meter is not a purely passive device and it adds some resistance according to its input impedance. That causes some current to flow leaking through the transistor and/or the resistor. \$\endgroup\$ Commented Sep 19, 2017 at 1:30
  • \$\begingroup\$ If so, is it impossible to see practically if voltage available on pins which are hanging in mid air? \$\endgroup\$ Commented Sep 19, 2017 at 1:34

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