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Smallest led controller

Hello everyone, I'm new to the forum so allow me to introduce myself. My name is Adrian and I have a Bachelor's in Mechanical Engineering. I will share as much knowledgd as I can with the rest of the forum.

I am trying to control a small strip of SMD LEDs (7 or 8) to raise and drop with the level of the music. I intend the signal to come from an audio cable and provide any additional power with a small battery. I would like the controller for the LEDs to be as small as possible

Thanks in advance for any help
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Unfortunately I can't see it available on surface mount, but an LM3916 seems to be what you're looking for.
 
Thank you Steve for your fast answer.

I had already come across that chip, unfortunately it is too big for what Im trying to do, have you seen anything smaller than that (18 pins?), what if I lower the number of LEDs that I'm trying to control?

Thank you again
 

(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
The other option would be to look at a microcontroller with an analogue input and in a surface mount package. You would require some external parts to condition the input signal. You can be as small as the available packages allow.
 
I just looked at the chip Steve suggested.

Are you looking for a bar graph type display, i.e. more LEDs light up as the audio gets louder, or just having the entire strip change in brightness with the level of the music? Steve seems to have assumed the former, and I the latter.

Bob
 
I am looking to have one strip with 7 or 8 leds. (4 green, 2 yellow and 2 red). The higher the music level the more leds light up. Is it doable? Thanks a lot for everyones help
 
The LM3916 does exactly what you're asking for, but apparently is only available in a DIP package, plus it requires some external components.

A small PIC (14-pin or so) with a built-in A/D converter would work. You'll need 8 pins for the LED outputs (unless you multiplex them, not really worth it with only 8 though since you'd still need 6 pins plus column drivers), plus an input pin for your audio signal which you'll want to filter with an op-amp buffer and low-pass filter (some resistors and capacitors).

Most of these parts can be had in really small packages if you need them.
 
Another option that has been brought to my attention is to design the circuit and have it packaged by a company. Is this viable? Or should I keep looking for something already designed?
 
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