Hi I am using a bluetooth module and giving output of it via differential to single ended using TPA6138 and it output given to audio output via aux or RCA analog. And I am having a tick tick sound when we hit advertising mode on the Module.
Advertising mode is like discoverable mode. It is like getting motorboat sound and surprisingly it is synchronizing with the LED's. I also have turned off the LED's by giving LED turn off command. Still I hear the tick tick sound. I guess it is in the ground because of ground isolation. How do we get the noise off the ground loop. Or is it the module creating the noise. It is actually a high frequency noise from the output of the bluetooth module the differential output.
TIP: I guess the sound is in the ground. I have analog and digital ground separated via 0ohm. I replaced it with ferrite bead it reduced it very lightly. Its random high frequency sound which is not going. Any advice would be appreciated. I tried a lot like taking the output audio running it via LOW pass filter also tried a second order band pass nothing worked.
Advertising mode is like discoverable mode. It is like getting motorboat sound and surprisingly it is synchronizing with the LED's. I also have turned off the LED's by giving LED turn off command. Still I hear the tick tick sound. I guess it is in the ground because of ground isolation. How do we get the noise off the ground loop. Or is it the module creating the noise. It is actually a high frequency noise from the output of the bluetooth module the differential output.
TIP: I guess the sound is in the ground. I have analog and digital ground separated via 0ohm. I replaced it with ferrite bead it reduced it very lightly. Its random high frequency sound which is not going. Any advice would be appreciated. I tried a lot like taking the output audio running it via LOW pass filter also tried a second order band pass nothing worked.
What are you using as an LED flasher circuit? That is the noise you're hearing - specifically, you are hearing the timer capacitor discharging or recharging.
You must isolate your logic from all audio circuitry. Logic grounds are dirty compared to audio grounds. The logic must have its own power supply filter capacitor. Isolate both sides of the logic power supply from the audio supply with resistors. Find the largest value resistors that will allow the logic to operate correctly.
The ideal solution is to have a separate power supply for the logic. You can use the same power transformer winding, but use a separate rectifier and filter capacitor for the logic. Do not connect the grounds together in any way. This works best.
You must isolate your logic from all audio circuitry. Logic grounds are dirty compared to audio grounds. The logic must have its own power supply filter capacitor. Isolate both sides of the logic power supply from the audio supply with resistors. Find the largest value resistors that will allow the logic to operate correctly.
The ideal solution is to have a separate power supply for the logic. You can use the same power transformer winding, but use a separate rectifier and filter capacitor for the logic. Do not connect the grounds together in any way. This works best.
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It is actually an Bluetooth Module. BC127. It says in its data sheet that it has to be placed at the edge specially the antennae for maximum range connectivity. But main was not to place any copper layer or analog ground in the top nor bottom layer. So i left it with no grounds copper template in that particular region. The noise is coming from the bluetooth module itself.
Either it's hooked up wrong, or else the module is crap.
Your timer circuit cycles whether the LED flashes or not. That's why you hear it whether the LED is on or off.
Digital and audio grounds should be kept completely separate, if at all possible.
This is why I prefer to design my own stuff. It's easier than trying to work around the deficiencies of commercial designs. Hacking someone else's design is often harder than doing it from scratch.
I'm building a preamp right now that has modest digital control, including a flashing LED for standby mode. The digital circuit is noisy as hell, but nothing comes through the audio chain. That's because I did it right the first time, instead of trying to save a few pennies or using a cheap module from ebay.
Your timer circuit cycles whether the LED flashes or not. That's why you hear it whether the LED is on or off.
Digital and audio grounds should be kept completely separate, if at all possible.
This is why I prefer to design my own stuff. It's easier than trying to work around the deficiencies of commercial designs. Hacking someone else's design is often harder than doing it from scratch.
I'm building a preamp right now that has modest digital control, including a flashing LED for standby mode. The digital circuit is noisy as hell, but nothing comes through the audio chain. That's because I did it right the first time, instead of trying to save a few pennies or using a cheap module from ebay.
Isolates the grounds, somewhat.
Artie's right. The larger the resistor, the better.
Your "120 ohm ferrite bead" is 120 ohms at a frequency much higher than the time constant of your circuit. It won't filter out the lower frequency components of the noise. Look at the datasheet.
Can you use a relay to isolate the grounds? That's what I'm doing. I think it really makes it simpler, and offers better results.
Artie's right. The larger the resistor, the better.
Your "120 ohm ferrite bead" is 120 ohms at a frequency much higher than the time constant of your circuit. It won't filter out the lower frequency components of the noise. Look at the datasheet.
Can you use a relay to isolate the grounds? That's what I'm doing. I think it really makes it simpler, and offers better results.
Provide a schematic or block diagram of your setup and maybe I can help you.
As far as logic circuits, my designs only drive relays or LEDs. The audio and logic grounds are completely isolated. The audio circuits are switched by the relays.
I don't know why anyone would do it any other way. There is no reason, no excuse for an LED or logic chip to share a ground with the signal ground. That's just lazy.
As far as logic circuits, my designs only drive relays or LEDs. The audio and logic grounds are completely isolated. The audio circuits are switched by the relays.
I don't know why anyone would do it any other way. There is no reason, no excuse for an LED or logic chip to share a ground with the signal ground. That's just lazy.
Do you have a completely separate power supply for the TPA613? Did you try the 10 ohm resistor?
Are you using their breakout board? I can only ASSume that the breakout board has the grounds parsed properly. Does the breakout board have separate logic ground, signal ground, and shield ground? Hook these up properly and your problem will likely be solved.
Are you using their breakout board? I can only ASSume that the breakout board has the grounds parsed properly. Does the breakout board have separate logic ground, signal ground, and shield ground? Hook these up properly and your problem will likely be solved.
I tried DC-DC Isolator even that dint work.
Ok so I have Bluetooth module connected to 5V and Digital ground. The output differential is going to TPA 6138 which is differential to single ended Output of this as single ended going to volume IC TPA 6130 which is Analog ground. Output I am giving to Aux output.
Voltage regulator 24V to 12V via linear regulator, 12V to 5V linear and 5V to 3.3V linear.
Ok so I have Bluetooth module connected to 5V and Digital ground. The output differential is going to TPA 6138 which is differential to single ended Output of this as single ended going to volume IC TPA 6130 which is Analog ground. Output I am giving to Aux output.
Voltage regulator 24V to 12V via linear regulator, 12V to 5V linear and 5V to 3.3V linear.
I tried 3 different switchmode (class D or T) poweramp boards from Parts Express, and two of the three got ugly one pushed near or into clipping (overdrive). The first one (Sure AA-AB32155, TA2024 2 X 15W) broke out into very high frequency oscillation bubbles, on the 1kHZ sinewave, just short of clipping. That would fry your tweeter and probably sound horrible. The second one went into a 2-3 HZ oscillation when pushed to clipping. It appeared to be a thru hole components version of the one good board (same switchmode chip). The 3rd one (TPA3116D 2 X 50W into 4 ohm) appears to work fine, even when pushed pretty far into clipping. Since all 3 boards came without any documentation at all, I can't tell you why each board did what it did. These boards/designs are apparently not very well tested, if at all. I was using the Yuan-Jing 100W voltage boost converter board, driven by a 12 volt power supply in all cases. The booster board converts 12VDC to anything up to 35volts. I had set it for 24VDC, and it appeared to work great with the one board. The board you have may just be a bad design and not be fixable without documentation. All tests were done with an 8 ohm load resistor.
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