Transistor preamp to drive one LED

Leonard Jeffrey's picture

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Joined: Oct 22, 2021

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Transistor preamp to drive one LED
October 22, 2021 - 9:11pm

I am trying to build a 9 volt powered circuit that amplifies an audio signal around line level. The load is one or more LEDs. It must not use any op amps. Preferably one or two transistors. A level pot before or after the transistor is OK. 

Sourav Gupta's picture

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Joined: Feb 12, 2018

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What is the specification of the input?

Leonard Jeffrey's picture

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Joined: Oct 22, 2021

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A stereo line level input. Music coming from an audio mixer, for example.

Sourav Gupta's picture

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Joined: Feb 12, 2018

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Look for Vu meter circuit using transistor. It will work.