Sound Reactive LEDs in portable speaker

[AndrianStoychev]

Hi guys im really new to electronics I have some very basic knowledge , I am good at making soldering a schematic but almost no idea what does what and why. Im a DIY fan and love doing some small projects (sound related mostly)like a "Car stereo 2.1 home audio system powered by a PC PSU " and my 2 current projects are 1- a portable 2.1 channel speaker with bluetooth and 2-Stereo 2.1 home audio system (using good old 2.1 speakers amplifier board and a MP3 module board) with sound reactive LED sides.
Here is the 1 model I sold :
Here is 2.1 with LED sides so far , it was gonna be a car stereo again that why it has it in the photo but I decided to use the 2.1 amplifier and an LED power module to power the 2meteres of LED strip (around 1meter on the left and right ) and the MP3 module :

Here is the basic idea for the portable on (exept im using less batteries and different value of resistors for the RC filter):

I plan on selling the home model again and keeping the portable one or keeping them both.

And finally here is what I WANT to do but have NO IDEA how and need help with:
1.Making the LED strips in the home model blink to the ligth (they are only cold white) (I previously added an on/off switch separate from the other circuit for them)
2.And for the portable one a circuit that will run on a 5V power supply that I can add a few LEDs that either : blink to the music (like 4 or 6 or 8 leds flashing with the music ) or like a mini VU meter with 6 or 8 leds ( 2x3colors OOOOOO or 2x4colors OOOOOOOO)
Thanks in advance guys.

 

[audioguru]

You said "LED strips" but do not buy the strips already made because they are powered only from 12V, not 5V. Making your own groups of LEDs to be powered from 5V then each LED needs to have its own current-limiting resistor.

I guess you want a VU meter for the white LEDs. How many LEDs and how many levels? Two groups of LEDs for stereo?

Do you wanty each lED color to be a band of frequencies (that is a color organ) so that blue is very low frequencies, green is mid-low frequencies, yellow is mid-high frequencies and red is very high frequencies? Do you want each color to be a VU meter? How many steps? How many LEDs will be connected together?

 

[AndrianStoychev]

The LED strips are in the Home model - the amps is powered with its own transformer from the wall transforms 230V to whatever the amp circuit needs (havent measure it) and Ill just connect a 12V DC LED Power Supply to the N L end of that transformer to power the LED strips and the MP3 module. Those I want to just blink in the rhythm of the music thats played.

For the portable version ( everything in it is powered on 5V) Im not exactly sure what to make , just want it to have some kind of sound reactive LEDs for effect. Maybe something like : THIS or **broken link removed**(but with leds) or THIS

 

[audioguru]

I do not know where in the world you are and what is your kind of music. I am in North America where the beat of most music is the bass so I would use a lowpass filter to feed a peak detector that feeds an LM3915 IC. I have a VU meter in my living room using an LM3915 LED driver IC. The IC lights the LEDs in the bar mode. So that it shows sound levels from the stereo, TV and conversations its input is an electret microphone, not a cable. it does not have a lowpass filter but it shows the beat if the music I listen to.

You showed a Monster Color Organ but it is not a color organ. All colors light at the same time. A color organ has each color light with the level of its band of frequencies.

If you use an LM3915 then it shows sound levels that are 3dB apart and each IC has 10 steps. Maybe you need two ICs that are cascaded to drive 20 LEDs? How many steps do you want? How many LEDs?

 

[AndrianStoychev]

I do not know where in the world you are and what is your kind of music. I am in North America where the beat of most music is the bass so I would use a lowpass filter to feed a peak detector that feeds an LM3915 IC. I have a VU meter in my living room using an LM3915 LED driver IC. The IC lights the LEDs in the bar mode. So that it shows sound levels from the stereo, TV and conversations its input is an electret microphone, not a cable. it does not have a lowpass filter but it shows the beat if the music I listen to.

You showed a Monster Color Organ but it is not a color organ. All colors light at the same time. A color organ has each color light with the level of its band of frequencies.

If you use an LM3915 then it shows sound levels that are 3dB apart and each IC has 10 steps. Maybe you need two ICs that are cascaded to drive 20 LEDs? How many steps do you want? How many LEDs?

Both speakers are 2.1 channel so they both have a low pass filter - on the home model I dont know the cutoff frequency cuz it was a store bought filter a friend gave me , on the portable one its an RC filter with a 50Hz cutoff . Yes I want the home model to blink with the bass , the simpler the better. And for the portable one either just bliknking with the bass again (1 set of 2-3 LEDs) or something simple like THIS which to double (cuz it prob mono) for left and right signal.

 

[audioguru]

The new video sounds like it has no bass and most of the LEDs are always lighted.
Bass is almost always in mono (that is why you have only one sub-woofer and not two of them) so having two LED systems in stereo will have both doing the same things.
2-3 LEDs draw a low current so the sub-woofer amplifier should be able to power them but your power supply voltage is almost nothing at only 5V, I will calculate the output signal:

The PAM 8404 stereo amplifier produces 3.2 Whats per channel when it is clipping like crazy into 4 ohms with 10% distortion but its datasheet shows that it begins clipping at only 2 Watts. Then its output voltage is 2.83V RMS which is 4V peak which is barely enough to light some colors of LEDs. Since the voltage is so low then we must know the exact forward voltage of each LED so that we can calculate an accurate current-limiting resistor. The LEDs can be connected with two of them back-to-back oppositely so that one lights on a positive half-cycle and the other lights on a negative half cycle then one resistor limits the current for both. Try it without a complicated peak detector circuit.

 

[AndrianStoychev]

Ok lets leave the portable one for now , how about for the home model with the 12V lead strips , there are RGB LED controllers with sound reaction but they suck nad they cost alot and im using a 1 color strip (cold white) + I dont want a bunch of effects for it , just to blink in reaction to the sound ( to the bass ). What would be the easiest way to do this .
P.S. Not sure what the amp in the home model exactly outputs in terms of watts to speakers , since its recycled from old 2.1 speaker system

 

[audioguru]

We need to know the output voltage swing from the sub-woofer amplifier by calculating it from the continuous maximum low distortion power into a certain speaker impedance.
12V peak is 8.48V RMS which produces 9W into 8 ohms or 18W into 4 ohms. But do you operate the amplifier at its maximum rated output power all the time you will use the LEDs? I doubt it then the LEDs will be so dim you might not see them.

A blue or bright green LED is about 3.2V when bright and is about 2.5V when very dim. Then an amplifier that produces 9W into 8 ohms will light the LEDs brightly during sound peaks. If the amplifier produces more than 9W into 8 ohms then we must add a resistor in series with each group of 3 series LEDs. Amplifier power that is 1/10th (0.9W) sounds half as loud then its peak voltage is about 2.7V but the groups of 3 LEDs in series are very dim when the peak voltage is (2.5V x 3= ) 7.5V so you have a big problem because if you turn down the volume only a little then the LEDs will never light. A fix might be to amplify the sub-woofer output signal to the LEDs but then loud sounds will burn out the LEDs. The solution is a VU meter then some LEDs will light brightly at almost any loudness.