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vu led

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MrSmither

New Member
hi!
My father is an electronics engineer and tells me thet i can get the output of a guitar into a circuit turn on a certain number of leds (1 to 10) depending on the volume of the output of the guitar...
i have had a look round and seen that everyone uses an LM3915N circuit bored but i have a feeling that you could do it with diodes given the drop in voltage every time the curent goes though it...
can anyone give me a circuit or something to do this with diodes if possible!
thanx in advance!!
MrSmither
 

Sceadwian

Banned
The LM3915's are only 3 dollars, why would you not want to use one.

Stereo VU Meter

Uses the the diode drop of the 1n4148 to provide the bias for the transistors.
would work, but as you can see it's ridiculously more complex than an LM3915, and if you want stereo just use two LM3915's

If you add up the parts for a discrete solution it's going to be more expensive than the IC and the few resistors/caps it need to work.
 

audioguru

Well-Known Member
Most Helpful Member
I buy surplus brand new National Semi LM3915 ICs for only $1.00 each.

The scale of an LM3915 is logarithmic like your hearing's response to loudness. Using diodes is not logarithmic.
 

Sceadwian

Banned
The circuit linked tries to take that into account by gradually decreasing the base resistor. Never built it, don't want to bother trying to simulate it. The LM3915 I'm sure does it better.
 
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