Bluetooth Ground Loop Isolation

My method of eliminating ground loop noise in DIY battery powered Bluetooth Players
Parts List:
Murata NKE0505SC (5v supply) or
Murata NKE1205SC (12V supply)
Capacitor : 4.7uF
Inductor: 47uH
These should be available from any large parts house.
USB Type A Female Right Angle DIP jack
USB 3.5mm Bluetooth audio adaptor
Proto board
These are easily sourced on Ebay or Amazon or Alibaba

[@siberx4]

Word of warning: Those small monolithic isolated power supplies like the Murata one shown in the video are in general very poorly regulated, especially at light loads. The datasheet specifies a 10-15% variation in load regulation from 10% load to full load, meaning a "5V" supply could swing as much as 0.75V across its output range (generally just barely acceptable for USB devices). Worse still, they're almost always "unspecified" below 10% load, meaning the regulation is generally awful at very light loads. The Murata datasheet actually states output voltage can rise to as much as TWICE the rated value for loads below 5% (so 10V on that supply), which can easily kill a low-current device that's not expecting it - ask me how I know. Options for avoiding this include: 1. Ensuring you don't "oversize" the converter (make it just big enough for the load current of your bluetooth receiver, keeping in mind if your receiver has a low current "idle" mode when it's not connected to a device) and making sure you never unplug/replug the bluetooth receiver when the circuit is powered. 2. Adding a "dummy load" resistor to draw a bit of current all the time. The shown converter is rated to 200mA, so keeping it above 10% only requires a ~250 ohm resistor that will dissipate 0.1W, so a quarter-watt through-hole resistor would work fine here. 3. Putting in a Zener diode to shunt voltage if it rises above a certain point. A 5.6V or so Zener could do this, but Zeners aren't generally that "sharp" at low voltages like this so it might not regulate much better than the simple resistor, and is more expensive (you're also less likely to have one lying around). Also note that you might run into problems depending on what USB port you're using to power the receiver - if the data lines are connected to something else (like the vehicle), it could prevent you from breaking the ground loop depending on how the rest of the system is wired. Best to ensure you're using a cable or circuit that lacks the USB data lines completely (like the demonstration shown on a breadboard here) to avoid that issue entirely. Otherwise, this is a great alternative approach to an isolation transformer, as it will preserve the audio quality on the analog audio side of the circuit (audio transformers will typically negatively affect audio quality, especially on the high frequencies, at least a bit).

[@Twitchyii]

Thanks for this comment, helped me with some of my concerns. I've just recently spliced aux into my older Lexus by stealing the CD changer audio lines and that worked out great. I decided I wanted bluetooth, so I bought a battery powered one and that worked great. I decided I'm too fancy to have to charge a bluetooth device and press a button to turn it on each time I enter the vehicle, so I bought a higher quality 5v usb powered bluetooth receiver and tied it into my car amplifiers ACC and GND via a 12v to 5v buck converter. I'm getting noticeable ground loop when paused, playing quieter audio or audio with breaks of silence in it. If I were to replace the buck converter with a 12v to 5v isolator like the one in this video would that potentially work? Would simply a 3.5mm ground loop isolator between the aux cable and bluetooth receiver be enough? Also worth noting, the ground loop noises only play on my right channels, all of them, but none of the left channels. Not sure what thats about.

[@siberx4]

@@Twitchyii You can break the ground loop on either the 3.5mm aux side or the power side, doesn't matter which - the advantage of doing it on the power side is that it should have less effect on the audio quality compared to the analog audio side of things (unless the power converter you use introduces a lot of its own noise). One of these isolated converters as shown in the video (with the caveats I mentioned about minimum load and ensuring the data lines are not connected) should do the trick for your scenario, if the noise is in fact caused by a ground loop. Not sure why you're only hearing it in one channel, but RF works in mysterious ways so it's hard to predict where problems will manifest. Also note that it's possible your noise is caused by your buck converter outputting a noisy 5V signal rather than a ground loop. An electrolytic capacitor in the 50-500uF range across the 5V output might help with this if that's the problem in your case, or switching to a different buck converter might alleviate it.

[@RegiPavan]

Finally I found your channel, that's explaining is what I needed... Thank you!

[@ryanball2882]

Really helpful video! One of the best on youtube for getting rid of ground loop isolation. Keep making videos, your work is absolute perfection.

[@robertcartier5088]

The beauty of this solution is that, unlike other devices that try to filter out the noise that is already there in the audio signal, this method stops the noise from being created in the first place!

[@MrTangoviking]

Thank you, your idea led me to my working 12v-solution with a Mornsun B1212S-2W, coupled with a 2.2uF cap, 12v bluetooth receiver. Be advised anyone reading that pin out is different compared to module in video. Glad I checked the datasheet!

[@orionthehunter9107]

I found on ebay a isolation converter that actually has the pins marked. Input WSTECH DC9-30v Output DC 5v1A

[@brayannexon4613]

This video is an absolute godsend to me because I have been frustratingly trying to solve the ground loop in my cars bluetooth module I added. I'm going to give this a shot.

[@jabacarai4187]

Nice... i was avoiding this solution, but it is the bes one so far so... thank you!

[@tomek9966]

THANK YOU! Did it as many people on YT without capacitor and a choke and it DID NOT WORK! Parts ordered. Cheers!

[@djedvis]

Sorry for replying after 7 months, just watched this video. Could you tell me if it worked? And what capacitor and inductor you were using?

[@selvaselva1071]

Nice video demonstration man. It is very good and 100% true. Most of the people never knows this thing.

[@siamak1246]

Great. Thanks for your teaching and time.

[@MDLAV8R]

Great solution. Thanks for taking the time to help others like me!

[@codebeat4192]

Glad to found your video! Many thanks for sharing this useful educational info (and demo). I have build some amplifiers with bluetooth and all of them have this kind of ground-loop noise (but only with bluetooth). Using capacitors can reduce the noise but cannot eliminate it. I have one made and the noise is absolutly terrible, not useful but by seeing this I think I can revive the project. Many thanks!

[@nizzyamps1317]

Thanks. I hope that this is a viable solution

[@codebeat4192]

Today I started to experiment with an USB sound-card (and class-d amp) and got the same problem, other noise but noise (data noise). Because the component you recommend isolates the ground, I did a little experiment with an other powersource connected (in fact similar to this) to the sound-card instead of the USB power, only datalines connected to computer or other device like a phone. As expected the sound-card turns on (powered by the external power source) but doesn't work except when I connected USB ground again (share the ground with the external power source). Because I still need to connect both grounds, this device doesn't make any sense because the ground is the noise generator (and it is required to connect both grounds). Any idea how to solve this? Is there a way to fool the usb host so it doesn't require to share the seperated grounds or is this a dead end? Many thanks for your time and answer if you have one. ;-)

[@nizzyamps1317]

This solution works in this case because we are breaking the ground loop at the power end. In this case there are no USB data lines that are at the same ground potentials as the power supply. I would think that the only way break that loop would be to isolate the data lines. Have you try a transformer type isolation device on the data lines? That might work as the USB data ground would be connected at the computer end but the amp side would float?

[@Darieee]

Thanks, was really curious how this sounds - only heard about it up to now

[@Rayyarhs]

Worked! Thnx! I had 2 bt modules on the same power supply and when i separatet the power supplys the house disapiert 80%

[@akashbiradar2715]

this is helping me in 2021 ty brother

[@Synthematix]

Finally, a solution, thanks for this.

[@thisisyourcaptainspeaking2259]

In the case of using a common power supply to operate both modules... Remember, the bluetooth module generates an interesting step-function type noise (buzz) as the IC consumes current. These audible pulses occur in the power supply and will come through the audio channels in the case of poor grounding between the two. I suggest soldering one or more heavy and short straps between the amp and bluetooth module ground planes. I use solder wick braid for this.

[@Bobo-ox7fj]

Interesting. Do you use wick with flux? I wonder if it would be likely to corrode over time

[@thisisyourcaptainspeaking2259]

@@Bobo-ox7fj Depending on the flux type and humidity, it can but not typically with rosin flux. I have noticed bacteria can grow in rosin flux. If there's any concern and as general practice because I prefer the look of a clean pcb without flux everywhere making it ugly, I often use MEK (methyl-ethel-ketone) solvent in a small brush to wash rosin core flux off my pcb's.

[@brewster6049]

Thanks, very useful, i wanted to buy a 'integrated' Bluetooth amp for my diy boombox but now i see it's best to have separate amp and Bluetooth module. (It does get allot more expensive buying everything separate, gives me doubts) How come it's so expensive? Make me wonder about powering the bluetooth dongle separate (in case of having the batteries and things needed at hand), that would also do the job? I don't have the items yet so i can't test it.

Hi! Good job! But i have a question about the ground of BT receiver. This is not connected to common ground of amplifier and power supply? Or the BT receiver output ground is floating and not connected to ground input? Thanks!

[@nizzyamps1317]

The output (-) of the BT board is connected to the input (-) of the amplifier. So it is in fact connected to the power ground of the amplifier. However, the BT output (-) is floating due to the isolation transformer.

@@nizzyamps1317 HI! Now makes sense! Thanks!

[@stradic4000]

Hi, Thanks for your explaination. Do you know the same kind of solution for 9V to 5V and for 6V to 5V?

[@orionthehunter9107]

I hooked it up per your instructions and it hums even louder. Now if I put my hand close to the isolation converter and touch it it hums really loud. I noticed that you used a USB port to connect the Bluetooth. Would it make a difference that I removed the female port that was on the bluetooth and directly soldered the dc 5v + and - to the module?

[@ArvinG]

Is this ground loop the same for amp? I have PAM8403 module with 2x5w 4 ohm speaker connected to pc via USB(5vpower) + 3.5mm jack(input)? They do work properly about 20% of volume but more than that the speaker started popping. How come other premade pc speaker that are also powered by only PC usb don't have ground loops?

[@fuglyyyyy]

Hi, I have a similar setup, but it is entirely 12v, Is this the right kind of part? MeanWell (D/S)PU01M-12 Should I use different rated capacitor and inductor for 12v?

[@catalinzamfirache5771]

Thank you for sharing this solution. This is more expensive than the bluetooth receiver itself. The hum is because the amp and BT receiver is sharing the same power supply. I hope i can find a fix for using this receiver in car without hum.

[@dandopa1990]

Did you find a solution?

[@myelectronics4203]

have u fixed ?

[@orionthehunter9107]

I have a couple of questions. 1st- Does it matter if the capacitor is polarized or not? 2nd - is there a direction for the inductor? This is my first Bluetooth project

[@SchmurtzAlex]

Hi, What kind of inductor should I use ? 1/4W , 1/2W or 1W ? Thanks for this useful video !

[@daniiieel]

I used this circuit diagram with my B1212S-2W but I didn't get the noise out of it... How to do it?

[@ABbuggin]

I followed your schematic using a NMH1205SC (12v in, 5v out) as suggested in your list. It's a 5 pin converter (instead of 4 pins). Testing the output voltage across pins 4/6 (as labeled by Murata) produces apprx 14v. If I test the voltage across pins 4/5 or 5/6, I get apprx 7v. Funny thing is pin 5 is supposed to be 0v. I've confirmed this on two separate converters. Any ideas?

[@nizzyamps1317]

Ive just noticed (thanks to your comment) that the chip I used in the video isn't the NMH series chip, its a NKE series chip. I've corrected the comment section. The NMH1205SC will work just fine. The inductor and capacitor values are the same as the NKE1205SC. However, the pinout is just a little different. Pin 1 ans 2 are the Vin pins. Pin 1 is V+. Pin 2 is V-. So from your 12V power source, Pin 1 is +ve, pin 2 is -ve (Gnd). Pin 5 and 6 are output. Pin 5 is output V- (Gnd). Pin 6 is output V+. So you would connect your bluetooth power source to Pin 6 V+ and Pin 5 V- (Gnd). Again: Pin 1: Input V+ Pin 2: Input V- Pin 4: no connection Pin 5: Output V- Pin 6: Output V+ Pin 4 is a -5V output . You won't use it for this application. It is used for split power supply chips. The reason you are getting 7V between pin 5/6 is probably because there is not load on the output. When you hook up the bluetooth, it'll go to 5V. You can confirm this by putting a 1K resistor across 5 and 6 and then measuring the voltage across 5 and 6. It should be 5V. I hope this helped and I'm sorry for the confusion. Let me know if you have any other questions.

[@ABbuggin]

Awesome, thanks for the info. I'm actually going to use a 5v output converter instead with a linear voltage regulator. The voltage in a vehicle varies too much (12.2v-14.5v) I feel for the 12v output regulator to be reliable. I considered using a resistor, but then that may drop the voltage too much during times that the vehicle is not in use (I play my radio a lot when working on my truck).

[@nizzyamps1317]

ABbuggin yes. If you can go thru a regulated power supply first it would be best. However, those chips are pretty robust.

[@satnaamwaheguru2479]

Hello NizzyAmps CSIMC YX48D05-10 isolator, but cant find the capacitor or inductor needed, I tried to find the datasheet but no sucess, If you can advice that be great! thanks in advance for great video I was searching from long time.

[@anthonypeverill2326]

Hi, great work man. Have you ever done any work with the noise/ground loop on a tda7492 Bluetooth amp?

[@nizzyamps1317]

No, theres not much you can do in the case where the bluetooth amp is integrated with the amplifier board. That's why I usually use a separate BT module and amplifier

[@mhess427]

Very interesting explanation. I don't know a lot about electronics but I was able to follow along. I'm assuming the reason I'm hearing ground loop interference from the Bluetooth transmitter in my car is because it is powered and grounded along with the factory car amplifier. How would I go about getting rid of interference in that case aside from powering the transmitter with its own battery?

[@ecko3957]

the buzzing sound travels through the lines of the dc power supply, which is why the power supply is isolated or you have a good filter to eliminate that noise.

[@tigidongtigidig]

Please help me, I am currently building my diy portable speaker.I have 2 20w 4 ohms speakers connected to PAM8610 amplifier powered by 3S2P 18650 batteries which has an output of 12 volts. I want to connect the bluetooth receiver which only requires 5 volts to the same 12v source of the amplifier using a DC-DC step down module. And i heard a lot of people complaining about ground noise. In this case assuming that the voltage is stepped down to 5v, what capacitor and inductor should I use and where will I connect it? Please help me. I have the slightest knowledge about electronics since I’m in the medical field. And so far, your solution is the best. Please haaalp

[@crisitanleonardo8175]

Would you please tell me what size capacitor and inductor I need if I where to use a 12-12 isolator. Note. It will be for my car so it will be power by a car battery 12v

[@nowjoel2830]

Thank you!

[@jengkywengky]

Hey there! Great video.. I'm wondering if an isolation transformer on the output of the bluetooth will do the same job? Why do you think the power supply isolation is better? Thanks!!

[@nizzyamps1317]

Yes you can do that. It will work well.

[@AdvanceNowRC]

@@nizzyamps1317 Could you recommend one please?

[@alionur54]

I have a TPA3118 mono module. I modded it, decreased to 20db gain. I added a potentiometer for volume adjustment. The pot when full and zero level no noise but at middle levels i m hearing noise. How can i eleminate this problem?

[@Friendroid]

would you still need that component if you used a 5v power supply for the amp and another 5v powrt supply for the bluetooth?

[@nizzyamps1317]

If you use a separate power supply for the amp and for the bluetooth you shouldn't have this problem. The problem comes with ground loops when you are trying to use a single supply.

[@Friendroid]

NizzyAmps Thank you, using two separate batteries solved it for me. I'm using the XS3868 Bluetooth module and TDA2822 , each with a 18650 battery powerbank.

[@TimotheosBlack]

Great work! This is the answer I have been looking for. I am a newbie to electronics, do you know what value inductor and capacitor to use for a 12v dc to 12v dc isolator? Help would be greatly appreciated

[@nizzyamps1317]

from the Murata nke1212sc data sheet: L=68uH C=0.47uF.

[@robertovalinhos27]

@@nizzyamps1317 . thank you! brasil

[@blazemathews]

Hey great explanations. I have used 5v to 5v DC-Dc isolating module in my DIY bluetooth speaker I stil have ground loop. Here's how i connected the converter, The 5v power input to the amplifier and i removed the sheath a little from both +ve and negative wires and connected the DC-Dc isolating converter there and connected it to the USB Bluetooth module. Is that type of connection ok? I use PAM8403 with two 3 w 4 ohm speakers. and 1 more thing there's a slight hear beat like thump from the speakers as well. Can you suggest me the inductors and capacitors of the right value so that i solve this issue?

[@nizzyamps1317]

If I understand correctly, you have it connected properly. Not sure why you are getting the sound loop

[@blazemathews]

Thanks for your reply.What about the slight thumping like heart beat pulse what shall i do for that? Any capacitor or inductor is should use?

[@thebarronflights]

I will try this and let you know the results, though the pins you showed on the transformer were out of shot.

[@andivisio]

What is replaced part for this?coz in Indonesia there is No part Murata. Thx.

[@toto073081]

Can i get source from the voltage regulator to connect to the isolated dc dc regulator?

[@thanatoskarnage362]

can you post a parts list and where to order from. I'm fairly new to mini amps and this would solve my only real problem with my builds.

[@nizzyamps1317]

Done. Ive added a parts list to the description box

[@toddsalters]

Help, I'm trying to use a Bluetooth board and a small amp like yours but I can't get rid of the noise. The only difference is I'm using an electrolytic capacitor. I did get rid of the noise by hooking the amp and Bluetooth to separate batteries. Any input would be greatly appreciated.

[@codebeat4192]

Dude, watch the video.

[@satyabratasenapati7376]

Hi, Is there any cheapest method available for eliminating ground loop noise?Like you told by filtering it can be eliminated. I have seen most bluetooth speaker uses differential input amplifier to eliminate the ground loop noise. But in my bluetooth speaker configuration I am using single ended class d amplifier so I am not able to eliminate the ground loop noise. I mean other than DC to dc converter is any other method available . Thanks .

[@manasteel98]

How much power does your BT receiver need? I want to do the same thing you're doing, but use a chromecast audio. However I don't think 200mA from the isolator will be enough.

[@nizzyamps1317]

Tim Wellington you might not be able to use this for a chromecast audio. I haven't tried. It works well with a generic BT stick tho

[@stevenmobley5882]

Chromecast is about 2W, I think. Should be able to get a 3W DC-DC and set it up the same way.

[@GabrielRodrigues-nt7lb]

Assim, para parar a respiração ofegante é apenas adicionando outra fonte de alimentação para o módulo Bluetooth?

[@nizzyamps1317]

Sim, você pode usar 2 fontes de alimentação. I hope the translation made sense.

[@ArvinG]

Do you know any transformer for 3.7v-4.2v or will the 5v work? I wanna use a lipo batt without booster.

[@nizzyamps1317]

you'll pretty much need to be at 5V. So if you are using a lipo battery it will need a 5V regulator

[@dougpasserini]

Nice job! I've been looking for a solution like this since long time ago.... Could you please share capacitor and inductor specs?

[@gregniznik587]

The capacitor and inductor vary by the murata chip used. For this specific one the inductor is 47uH 4.7uF. If you pull up the data sheet it'll specify the values.

[@gregniznik587]

These values are for both the Murata NKE1205 and NKE0505 chips

[@hansdegroot652]

Hi. I am using these for a a few things now they are brilliant but they die very easy if you make mistakes. But I never used the inductor or cap before. I think without it sounds fine. what are they for?

[@nizzyamps1317]

yes, they are delicate. The inductor/cap is really just a filter. if you have a clean DC input, they really aren't necessary

[@satyagiet2]

I agree with your experiment using dc- dc isolator solves the problem.I have the same problem when I am supplying 3.7 volt from a common battery to both Bluetooth audio receiver & class d audio amplifier. So in your video you told that an LC filter at speaker output also solves the problem.Is it necessary in a filter less class d audio amplifier.Please comment.

[@HaimPeretz]

How much Amper the dc-dc give? I need something the clean the ground loop noise form chromecast audio that share the power with the amplifier

[@nizzyamps1317]

it gives no amplification. It is a power supply only. For your situation you would be better off with an in line ground loop isolator between the chrome cast and amplifier

[@dandopa1990]

I really need your help... I bought a bluetooth module for my car. And it have that buzz noise...I connected the Bluetooth wires to the cigarette supply.

[@casper2501]

You basically connected the radio and Bluetooth module to the same power supply which causes ground loop hum noise. You can use powerbank to power your Bluetooth module and thus isolate the grounds. :D

[@MarioSalasEspinoza]

Can anybody help me out, what should be the inductance for a NKE1212SC? I have one of those all in one 12v bluetooth modules.

[@nizzyamps1317]

Mario Salas 68uH. The cap is 0.47uF

[@jamesp2877]

What is the model number for the amplifier you're using?

[@zerk773]

What does the inductor do in this circuit?

[@f4phantomf4]

I just saw your video, and what you accomplished is exactly what I'm trying to do. I've got a bluetooth amp module powered by a 12v rechargable battery. The voltage is boosted by a boost converter for the bt module. The module also has a aux in jack. I wired the parts (the murata nke1212sc, a 47uh inductor, and a 4.7uh cap.) Between the battery and the rest of the circuit. Nothing rrally happened. Noise was similar, couldn't get music to play, then the Murata module smoked and stopped working. I checked my connections and were all fine. Any suggestions?

[@nizzyamps1317]

were you running the murata at 12V?

[@f4phantomf4]

NizzyAmps yes. I think I found my mistake. I purchased the nke1212sc version, as I knew I would be running 12v. But I didn't consider the inductor and capacitor, which I ran the same as yours. I've ordered different inductor and cap...so hopefully once they arrive it will work!

[@florenzioxiqlana5497]

I tried your solution for my system but the MEV3 stops working after a couple of minutes. I power the amplifier directly and the other components (two controllers) with the MEV3, having a load around 60 mA to 150 mA. I measured 0.06 A to 0.07 A at the input of MEV3 when running. Could you please help me to find the reason of this problem? My configuration: - MEV3S0505SC - 4.7 uF capacitor (Tantalum) - 10 uH inductor (09HCP)

[@davidschilling2949]

I'm not sure why thats happening. The MEV3 should be able to handle those loads.

[@spinnerpete]

I ordered the components, If this works I owe you a beer or three.....

[@Lankasurf]

Thanks for sharing! It took me over a year to find this solution. Great tutorial and audio example! Do you know how really cheap bluetooth speakers fix this problem?

[@nizzyamps1317]

Xantaz NL not sure how they do it.

[@rudiyang7790]

hi there thanks for sharing,.. I have a question though.. will it be the same effect (eliminate ground loop) if I'm using buck converter lm2596s instead of dc-dc murata isolation? thanks

[@nizzyamps1317]

Rudi Yang I don't think that the buck convertors are isolated. I've never tried it but I think you would probably still have noise

[@rudiyang7790]

one more question sir,.. would it be better results if I use the dc-dc isolation in bigger watts (2 watts),. because the pam8403 needs 2 watts for clean power,. and that b0505s is rated 200ma,..thank you

[@nizzyamps1317]

You only run the BT module off of the DC/DC convertor. The amp runs off your original power supply. You are isolating the power supply to the amp from the power supply to the BT module. For most BT modules 1W of power is plenty

[@rudiyang7790]

Thank you sir

[@batangenyodotcom]

Hi, can I use only the DC-DC isolator without using capacitor and inductor? Thank you.

[@nizzyamps1317]

You can, they are a low pass filter to eliminate noise but if your input DC is clean, its not always needed.

[@batangenyodotcom]

NizzyAmps thanks a lot.

[@seemoshaik]

You can try if you get an isolation DC - DC converter that is regulated internally

[@robertcartier5088]

Q: If the component truly isolates its 2 sides, why are the support component necessary? Doesn't 'no connection' inherently mean that no ripple is passed on at all? Why the extra filtering if there isn't anything there to be filtered? (In other words, I already have the B0505S-1W isolated converter, and may or may not have the inductor and capacitor, but I'm way too lazy to look for them if I don't really need them! lol)

[@nizzyamps1317]

the extra components are optional and act as a highcut filter if your power supply has some ripple

[@toto073081]

How much is the value of resistor to use?

[@poyrazoyunda6482]

thanks king 🎼🎼🎼🎼

[@nimalathilakarathna7834]

can you please explain how to connect R+,R- and L+,L- audio outputs to R,L,GND connector

[@Twitchyii]

If you're talking about the aux cable to the bluetooth receiver, its R+ to R, L+ to L then both R- and L- to GND(GND being the third wire in your aux cable, not a chassis or earth ground of some sort)

[@MrPaulSijben]

Great idea. Just built one. One question, my capacitor gets hot right away, without even any load on it ( 25V 4.7UF). Does that make sense?

[@MrPaulSijben]

never mind, it helps if you use regular capacitors and not tantalum capacitors which have a polarity....

[@sandramixon1734]

ceramic may be recommended / + review your power output capacity tolerances with their values@@MrPaulSijben

[@siegfriedgebauer4004]

hi, I'm new in electronics, so I have a little doubt. I have a project with an amplifier and a bluetooth module, both 12v so I have a 12v battery and the noise was horrible until I put a dc dc isolated 12v converter, but without a capacitor and an inductor. the capacitor must be at 16v? and the inductor make de voltage lower? Uf? uh? helps please! thanks man!

[@nizzyamps1317]

Siegfried Gebauer the capacitor should be at least 16v. I use small ceramic caps that are 50v.

[@nizzyamps1317]

The inductor doesn't drop the voltage to any significant value.

[@siegfriedgebauer4004]

ok. and the capacitor it's a 16v if the dc dc converter works at 12v? and can be 4.7uf or higher? can use a 16v 100uf capacitor for example? and the inductor?

[@siegfriedgebauer4004]

I understand the why I need a capacitor, but can you tell of why is the inductor need it. thanks and regards! ( the converter is 12v and 1w hd I don't use capacitor and inductor it will burn it?)

[@nizzyamps1317]

Siegfried Gebauer you can run the converter without the cap and inductor and see what your noise level is like. A USB Bluetooth is not very sensitive to noise so you should be good. If you are going to add the cap and inductor use the manufacturer recommended values. Better minds than ours have figured this stuff out.

[@fullwaverecked]

Nice video, but where have you been?

[@MarshallSmith27]

I have a bluetooth module that is 6v at the lowest allowable voltage what would I need to use to do this?

[@nizzyamps1317]

Marshall Smith depends on what the voltage range of the amp is. Send me a link to your particular amp and I’ll show you how to do it.

[@MarshallSmith27]

TDA7492 Amp 4.2 Bluetooth board I have a buck transformer ran to the bluetooth board because one of the zeners didn't like anything above 12v and I have a step up transformer running to the amp at 25v for max output power. www.ebay.com/itm/Amplifier-Board-TDA7492-D-Class-High-Power-Digital-2x50W-AMP-Board-w-Radiator-1x/132588090812?hash=item1ededdb5bc:g:wxcAAOSwrklVOKIJ www.ebay.com/itm/Bluetooth-4-2-Audio-Receiver-Board-CSR64215-Wireless-Stereo-Module-Replacement/172867396249?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

[@PeterRome]

Excellent video. I have a problem with my system. Basically it's a small arcade cabinet. There is one 5 volts power supply that feed a raspberry pi, a screen and a PAM8403 amp. I think I get noise because the amp is sharing the power supply with the other component. Do you think that if I add this kind of isolation tranformer between my power supply and my amp I would get rid of the noise? Also what wattage do I need knowing that my speakers are 2 times 3 watts (4ohm impedance). Thanks a lot.

[@nizzyamps1317]

No, unfortunately this isolation transformer probably won't supply enough current to run the amplifier.

[@nizzyamps1317]

you may need something like this instead: kzbin.info/www/bejne/epvRl6BjaLOWgpo

[@PeterRome]

Thanks! that what I thought (you can find isolation tranformer for several watt but they cost a fortune). I actually ordered one of those ground loop isolator this morning ;) I'll tell you if it works. After watching your video and searching on the internet I've also found out that a capacitor between Vin and the ground of the amplifier board could reduce the parasites. Is that the reason of using one here? I'll give a shot with the capacitor if the ground loop isolator does not work.. I have another question, why do you put an inductor? Thanks for your answers.

[@nizzyamps1317]

The inductor and capacitor are suggested by the chip manufacturer. They form an LC lowpass filter to make the DC signal clean. However. Ive omitted it on several occasions and not had any issues. Please let me know how the ground loop isolator works! Thanks.

[@PeterRome]

Update: I received the ground loop isolator from amazon (www.amazon.co.uk/Isolator-HAVIT-Speaker-HV-X2-Black/dp/B01IETQQQK/ref=sr_1_3?ie=UTF8&qid=1524612002&sr=8-3&keywords=ground+loop+isolator). It solved my problem. I plugged it between the output sound of the raspberry pi and the input sound of the amplifier board. No more humming, no more parasites it's quite magic. I guess it's the way to go fro people who can't use an isolation transformer due to a too high current. Thanks a lot for your help! For those interested, this ground loop isolator also works to get rid of the parasites in cars in which a bluetooth receiver is plugged in the jack aux port.

[@ProfessorOzone]

It looks like you are using an isolator followed by a filter. Isn't this redundant? Can you explain the difference? Sorry if I missed it.

[@KolfMAKER]

Thnk, this was an issue I came across. Works for me! By the way, I am suffering from low volume output of my Bluetooth receiver module (KRC86B). I think I need to combine it with a pre-amp board. Do you have any suggestion which to use?

[@nizzyamps1317]

Ernst Kolvenbag I have found a few boards that have had very low volume. Those have had a 47uF cap included instead of a 470uF cap. I suspect a counterfeit board. A real board has plenty of power to drive an amplifier without a preamp.

[@karelbousson7719]

​@@nizzyamps1317 I read this comment after having ordered a KRC86B board. I checked the capacitor and it had a 47uF one... So to be sure I went back to uncle Ali and ordered 3 more of these boards from 3 other sellers to compare the sellers and quality of the boards. 2 out of 3 boards have arrived - One has a clean electrostatic bag where the board and capacitor (470uF)/LED are separated. - The other has a 47uF and a sloppy seal on the bag. I have yet to test all of the boards, so I can find out which sellers are to be trusted 🤔

[@webten7381]

My converter gives more output than input supplied, is it normal? Like i gave 4.8volts and output is 5.2 volts.

[@nizzyamps1317]

YEs, one it has a load on it, it should go to 5V

[@codebeat4192]

What is the function of the 47 Ohm resistor, limit current?

[@nizzyamps1317]

Illumation Streambutler it's a 47uH inductor. It's used with a capacitor to reduce noise on the D.C. Outpu

[@codebeat4192]

Oh okay, never seen those before in this kind of package, only coils. Are there any benefits using these kind of inductors or is it just ease?

[@giovannispinotti]

wow! definitely going to ckech this out. has anybody tried to cut the ground loop by ereasing some ground traces on the pcb itself?

[@umairarshad1106]

i have this issue in my bluetooth speakers. i am no engineer at all so don't know anything about it. can you please tell what can i do to remove hiss/high pitch annoying sound?

[@nizzyamps1317]

If the BT speaker is already built, it would be difficult. If you are building a speaker, you can add this module to power the Bluetooth board

[@umairarshad1106]

NizzyAmps ahan! Thanks for your reply.

[@dwiki83]

do you have any alternative from the murata chips?

[@thatguythatdoesstuff7448]

Any DC to DC transformer works. Supposedly, the audio grade transformers give you a better sound, but I've seen a number of examples where a general purpose DC to DC was used and the same results are achieved.

[@catalinzamfirache5771]

Mornsun DC DC converter.

[@jj-jo6wr]

can i use Inductor: 22uH instead of 47uH?

[@nizzyamps1317]

It won't explode. you should be fine.

[@jj-jo6wr]

Can I skip the capacitor ? Can I replace 47uH with 22uH?

[@nizzyamps1317]

If you skip the cap, skip the inductor. These form a high pass filter. One won't work without the other. Generally, as long as the input voltage is clean, the output will be clan as well.

[@arunbalakrishnan8978]

DC isolator is perfect, but the cheapest way is to add a capacitor with a value of at least 2200uf.

[@toto073081]

Whre to connect?

[@arunbalakrishnan8978]

@@toto073081 In DC power

[@2roti]

I have the adaptor and the noise it's on using the earphones. No ground loop. The conclusion is that noise it's not generated in any way from any ever ground loop. Even powered by external usb pack. How to solve this? This setup it's clear it will not help.

[@nizzyamps1317]

If its a hissing sound, it may be the amplifier. Some class D amps can be noisy. Hope that helps

[@2roti]

it's exactly the noise that you have manage to solve, i think it's an interference with the PIC on the board, sound like a digital communication.

[@nizzyamps1317]

It could very well be. Can you try another type of amp board? Then you can narrow it down to either the amp board or the Bluetooth board or a bad isolation chip

[@TheMazo02]

For me it works without the capacitor and resistor

[@davidherrera6856]

Another way? I don't have isolators

[@nizzyamps1317]

David Herrera you can try this instead: www.parts-express.com/audio-system-ground-loop-isolator-kit--265-007?

[@ArvinG]

Its expensive 5 dollar each =(

[@IceJackal1984]

no, this doesn't work.