Sound Reactive LEDs, Need help.

[Quinny13]

https://www.danielandrade.net/2005/12/06/howto-blinking-leds/#prettyPhoto

The link above is to a sound reactive LED circuit that i am trying to make, I am using a 12v power supply and 4 LEDs (a green 2.9-3.1v, a blue 3-3.2v, and a yellow and red both 1.9-2v), i plan to connect the circuit to my iPod. But i need help figuring out what resistors to use as limiting resistors and where to put them.
Any help is greatly appreciated.

 

[ronv]

How about 120 ohms between Vcc and the first LED.

 

[audioguru]

As I told you in your PM to me, the circuit was an Instructable designed by a little kid who knows NOTHING about electronics.
It is too simple so it might damage your iIPod or speaker amplifier, it might damage the transistor and it will probably burn out the LEDs.

It might light the LEDs on very loud parts of the program.

Here is my circuit. It uses an audio power amplifier to drive the LEDs with no damage to anything:

 

[Quinny13]

audioguru, thanks for the help, I'm not too sure i understand the LED portion of this schematic, is it possible to connect 4 leds(green,blue,yellow,red) or would that require substantial modification of the circuit? Due to simplicity and my lack of experience is there anyway to modify the schematic i pmed you to make it "safer" for my devices?

 

[Quinny13]

**broken link removed**
would it be possible to connect the 4 leds and a resistor to this? and also power the device with a 12v battery?

 

[ronv]

AG is right it is not a very good circuit but if you add another 120 ohm resistor between the +Plug and the base of the transistor it should kind of work. You might change the transistor to a 2N22222 it might blink a little better.

 

[audioguru]

audioguru, thanks for the help, I'm not too sure i understand the LED portion of this schematic, is it possible to connect 4 leds(green,blue,yellow,red) or would that require substantial modification of the circuit? Due to simplicity and my lack of experience is there anyway to modify the schematic i pmed you to make it "safer" for my devices?

The Instructables schematic is garbage!

My circuit can safely drive many pairs of LEDs that have similar voltages. Connect your red and yellow LEDs back-to-back reversed in parallel with a series resistor and connect your green and blue LEDs back-to-back reversed in parallel with a series resistor. Use Ohms Law to simply calculate the resistors.
With a 12V supply the output of the LM386 swings about 5V peak so the resistor values are (5V - 2V)/20mA= 150 ohms for the red and yellow LED pair and is (5V - 3V)/20mA= 100 ohms for the green and blue LED pair.

The LM386 power amplifier can drive up to 10 pairs of ordinary little 20mA LEDs.

 

[audioguru]

**broken link removed**
would it be possible to connect the 4 leds and a resistor to this? and also power the device with a 12v battery?

The PHOTO has no schematic and has no specs.
A CCFL might be a 120V AC or 240V AC Compact Fluorescent Light bulb so LEDs cannot be used with that driver module.

 

[Quinny13]

So would this be an accurate representation?

 

[Quinny13]

minus the fact that i connected the wires to the wrong lead of the battery

 

[audioguru]

View attachment 75136
So would this be an accurate representation?

The backwards battery will probably blow up the LM386.
The capacitor values must be correct.
The 100 ohm trimpot can be 10k or 20k ohms so it does not short-circuit the music source and kill bass sounds.