TIP31 Sound reactive LEDs

[Softmuppen]

I want to build the famous TIP31 Led circuit but I'm having some trouble. I've purchased the required components but I'm unsure of the actual circuit.

I've made a scheme for my circuit. I'm wondering where i should put my resistors and what Ohm-value they should have.

View attachment 61923

My second question is about the 3,5mm stereo connector. I've bought a connector but I'm unsure where my cables are supposed to be. My guess is that the left and middle pin is for right/left audio and the right pin is ground, am I right?

View attachment 61924

Thanks in advance!

 

[House0Fwax]

That socket looks like a 'switched mono' type, not a stereo unit.

 

[Softmuppen]

So it will not work for the circuit? I must use either right or left channel, i cant use mono?

 

[audioguru]

The circuit is an Instructable that was designed by a 10 years old kid who knows NOTHING about electronics:
1) The base of the transistor and/or the amplifier might burn out because it is missing a series current-limiting resistor.
2) The transistor and/or amplifier might burn out because the voltage might cause avalanche breakdown of the reverse-biased emitter base junction because a diode is missing.
The transistor and/or LEDs might burn out because a current-limiting resistor is missing.

You show a mono socket but it can be used to show the output from one of the two stereo channels. If you short the two stereo channels together into mono then the amplifier will probably burn up.

 

[Softmuppen]

Do you have a suggestion for a better circuit with a 12 volt power supply? I will order another 3,5mm connector.

 

[audioguru]

With only 12V then you cannot use four 3.5V white, blue or bright green LEDs in series because then their supply must be about 14V plus 2V for their current-limiting resistor. RED LEDs can be used because they use only 2V each.

It is simple to add a series base resistor, add a diode in series with the emitter and add a current-limiting resistor in series with the LEDs in that wrong circuit.

 

[Softmuppen]

Im using a 12V LED Strip. Should i use any resistor then? I Cant get the circuit to work.

 

[audioguru]

I don't know if your LED strip has built-in current-limiting resistors.
If you made the circuit as shown then maybe you burnt out the transistor, the LEDs and the amplifier.