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@Davenn, I grounded every part needed to be grounded from the start. We're good there.
@Rleo, So you think I should try removing the 18k ohm resistor all together?
I was thinking that the output (pin 4) should go to the string of LED's to power them. I'm not sure though. I've never worked with the TDA2050.
@Rleo, So you think I should try removing the 18k ohm resistor all together?
I was thinking that the output (pin 4) should go to the string of LED's to power them. I'm not sure though. I've never worked with the TDA2050.
In stereo circuits the left and right signals have information (sound) that is common to both left and right. They also have information (sound) that is exclusive to that input (left or right).
When you tie them both together (depending how you do this) you can get a result that is cancelling out the information that is common to both left and right. You may also double the common information from both left and right, which would be much higher than any signals exclusive from left or right.
The correct way to do it is like Steve said: tie commons from left and right together and to the common ground of your circuit. Tie a 47 ohm resistor one end to the Left input the other end of the resistor to the input of your circuit. Tie another 47ohm resistor to the Right signal input and the other end of that resistor to the input of your circuit.
This causes the Left and Right signals to be added together and sent to the input of your circuit. That way, all of ther information from Right and Left are introduced into your circuit.
Whew!!!
When you tie them both together (depending how you do this) you can get a result that is cancelling out the information that is common to both left and right. You may also double the common information from both left and right, which would be much higher than any signals exclusive from left or right.
The correct way to do it is like Steve said: tie commons from left and right together and to the common ground of your circuit. Tie a 47 ohm resistor one end to the Left input the other end of the resistor to the input of your circuit. Tie another 47ohm resistor to the Right signal input and the other end of that resistor to the input of your circuit.
This causes the Left and Right signals to be added together and sent to the input of your circuit. That way, all of ther information from Right and Left are introduced into your circuit.
Whew!!!
Update:
I have removed the 18k ohm resistor on pin 2 as Rleo and Davenn pointed out. Still, the LED's come on when I plug in the power adapter, and when I plugin my music sourc, the LED's aren't flashing.
The way I have the audio in set up right now is just
This is what you guys are suggesting, correct?;
I have removed the 18k ohm resistor on pin 2 as Rleo and Davenn pointed out. Still, the LED's come on when I plug in the power adapter, and when I plugin my music sourc, the LED's aren't flashing.
The way I have the audio in set up right now is just
Code:
L ----------
\_______
/
R ----------
Ground (goes to the common ground with everything else in my circuit.)
Code:
47ohm
L --/\/\/\---
\_______
/
R --/\/\/\---
47ohm
Ground (goes to the common ground with everything else in my circuit.)@Joshie: Yes, the second drawing is what everyone here is suggesting. We are not exactly agreeing on the value (47 ohms). You may want to experiment with that.
From looking at the circuit, it looks like the 18kohm resistor is adding some more bias from the +12 volt supply to the negative input of the amp. This may be needed in this circuit (or not).
It also looks like the lights should not turn on with no signal, but they should turn on when the input signal goes low. So, maybe the incoming signal needs to be bigger to switch the amp so that it will output a low signal and turn on the lights.
Anyone see this?
From looking at the circuit, it looks like the 18kohm resistor is adding some more bias from the +12 volt supply to the negative input of the amp. This may be needed in this circuit (or not).
It also looks like the lights should not turn on with no signal, but they should turn on when the input signal goes low. So, maybe the incoming signal needs to be bigger to switch the amp so that it will output a low signal and turn on the lights.
Anyone see this?
I suggested 47 ohms on the basis that your input was coming from something like a headphone output. That value is sufficient to protect the outputs. A higher value may also be acceptable, but remember that you have a capacitor in series and you probably don't want to create a low pass filter...
Guys, I am thinking maybe the circuit is wrong. I believe the 18kohm resistor should be in the circuit, but it should be going to ground (not +12). Here is why:
With no signal in, the dc voltages on the amp will be (approximately) 6 volts at pin 1 (+ input), and pin 4 at +12 volts will make pin 2 (- input) around + 5.4 volts (voltage divider 18k and 22k). C4 (22uf) is also being charged to the same 5.4 volts.
When a signal is applied and it's peak negative signal would need to drive the + pin down below 5.4 volts to switch the pin 4 output to a low output and turn the LEDs on.
When pin 4 goes low, we now have pin 2 tied to ground through both 18k and 22k resistors. C4 will keep pin 2 at 5.4 volts until it starts discharging through these two resistors. Once C4 is discharged enough to bring pin 2 below the voltage at pin 1 or the input signal goes high once again, then the pin 4 output will once again swing high and turn the LEDs off.
So, does anyone agree that maybe the 18k should be there? Only tied to ground?
With no signal in, the dc voltages on the amp will be (approximately) 6 volts at pin 1 (+ input), and pin 4 at +12 volts will make pin 2 (- input) around + 5.4 volts (voltage divider 18k and 22k). C4 (22uf) is also being charged to the same 5.4 volts.
When a signal is applied and it's peak negative signal would need to drive the + pin down below 5.4 volts to switch the pin 4 output to a low output and turn the LEDs on.
When pin 4 goes low, we now have pin 2 tied to ground through both 18k and 22k resistors. C4 will keep pin 2 at 5.4 volts until it starts discharging through these two resistors. Once C4 is discharged enough to bring pin 2 below the voltage at pin 1 or the input signal goes high once again, then the pin 4 output will once again swing high and turn the LEDs off.
So, does anyone agree that maybe the 18k should be there? Only tied to ground?
Last edited:
@sid
I've tried basically everything. I have tried the 18k resistor to +12v.. I've tried it to ground also. Both leave the LED's permanently on, not flashing to music. I've also tried it with no 18k resistor at all, and when I plugged in my phone to play music, same thing; but when I took my phone off I couldn't control the volume any more, almost like it fried my volume control. I reset my phone though and all was good.
Sadly, $20.00 in and a few weeks of digging I might have to give up :'(
I've tried basically everything. I have tried the 18k resistor to +12v.. I've tried it to ground also. Both leave the LED's permanently on, not flashing to music. I've also tried it with no 18k resistor at all, and when I plugged in my phone to play music, same thing; but when I took my phone off I couldn't control the volume any more, almost like it fried my volume control. I reset my phone though and all was good.
Sadly, $20.00 in and a few weeks of digging I might have to give up :'(
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