I am building a science project for my friend. We chose to make a VU Meter.

I am planning to make the Vu Meter as the schematic in the image:


The audio source will be 3.5mm jack output of a smartphone.

I am getting all the components except the c9013 transistor at local shops.

So can I use the 2n2222 transistor instead?

If not then suggest the changes to make it work.


2 Answers 2


The 2N2222 should be totally fine. Voltage, hFE, etc. all look equivalent for your purposes. There's nothing critical about the VU Meter design since it's merely switching the LEDs on and off.


You could also use the very common 2N3904 for this application.


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