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enter image description here

Actually 4.8 v dc is arduino nano output. In multi sim it works but practically not, transistor is 2n2222a npn.

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Meet Hadvani
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    google "low-side switch". – The Photon Aug 24 '17 at 05:43
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    Part of your circuit is good and part is wrong. Hint: you have to shuffle battery, bulb and ground. – Chupacabras Aug 24 '17 at 06:01
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    Also, the 1 milli-Ohm base resistor is a bit low... about 6 orders of magnitude. Not to mention that the voltage at the lamp would be 4.8V - Vbe (about 0.7 V). – next-hack Aug 24 '17 at 06:29
  • What is your question? In addition to what @next-hack said, your transistor will also run very hot. You have wired it as an emitter follower. It is not configured as a switch. – Vince Patron Aug 24 '17 at 07:07

1 Answers1

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Your circuit is incorrect. And as pointed out in the comments the resistor is too small to bias the base. Here is the circuit you should be using

schematic

simulate this circuit – Schematic created using CircuitLab The resistor value can be calculated using the following formula.

R1 = (V1-Vbe)/Ib, where Ib > Ilamp / Hfemin

Frank Donald
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