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Discussion Starter · #1 ·
Following are 3 picture of the noise at the battery and after a JMCB filter. Yellow is at the battery before the JMCB filter and purple is after the JMCB filter. The JMCB filter is NOT the BMW variant. I am in the process of determining if the $135 (Sierra) for the BMW variant really solves the problem.

1st picture is at the battery with the key OFF.

2nd picture is with the ignition ON but motor not running.

3rd picture is the bike RUNNING.

The older JMCB filter removes the high frequency junk but there is significant low frequency content remaining.

Are there other solutions? All suggestions welcomed...
 

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I get an annoying low level whine through my bluetooth connection when listening to audio from the bike while the engine is running. It's most noticeable when playing mp3's via a flashdrive in the usb port. This is because the volume needs to be higher for this source than the others.

I'm wondering if this filter reduces/eliminates this whine. Since I've been told its not just my bike and that it can be heard by most folks when turning up the volume on a quiet passage of mp3 sourced music on their 14/15 RT's, could you try to confirm if this helped?

Thanks,

Tom
 

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Discussion Starter · #3 ·
Is the whine a high or low frequency? The JMCB filter did reduce the high frequency noise but not the low. It is an inexpensive solution. The noise issue I am attempting to solve is the low frequency stuff. I will be checking out the use of a typical AC EMI/RF filter and will post the result. Could be a cheap, ~$5, solution (read about it on a forum somewhere...) for the high frequency stuff....

The issue will be putting a filter between the source of the whine and the audio device passing it. The source is most likely the alternator and it appears that bluetooth is part of the Alpine unit (the BT antenna is connected to it).

All my audio is hardwired and passes through a Motochello MC-200 comm system (CB, SAT/FM, iPhone). I get no whine whatsoever with the system. My only use of BT is between a Valentine One and an iPhone. All MP3 music is via the iPhone.
 

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It's a higher frequency whine (to my ears), definitely not a low (~100hz) hum. This is good news if a cheap, easily installed filter solves this problem.:)

Can you post a link to the filter you used and describe how you installed it (or better yet pictures)?

Thanks
 

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Discussion Starter · #5 ·
It should be here by next week.

Here is the filter.

Basically it will be 2 wires in (power and ground) and 2 wires out (filtered power and ground). The 3rd wire on the input is for a shield (adds caps between the shield power and ground) if needed or tied to ground (adds a cap to the output)

Here is the original forum where I found the concept. See BillA's reply and picture...

I will need something like this to solve the low frequency noise. ~$50 versus the $135-ish for the JMCB BMW version of the filter...

...it is a process...
 

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Discussion Starter · #6 ·
Just noticed that the parts I ordered are on a sloooooow boat from China - literally! So it might be a while before I get them - late July. Now that I have scoped the power on my RT, this part isn't as important in solving the low frequency issue.

In the interim, I'll work on low frequency options versus just or an all out purchase of the JCB03-RPLW versus what I currently have JCB03-RPLF. :think:
 

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I don't think the EMI/RFI filter is the solution. EMI is defined as frequencies from 150kHz to 30MHz. RFI is defined range is 30MHz to 1GHz. The low frequency component from your scope trace is 50Hz, which I assumed was at idle. Does this hum occur if your listening to music from your iPhone when its not charging? Noise might be intoduced when its charging. This may help to isolate the cause.
 

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Discussion Starter · #8 ·
It is just a low order (1st) passive filter (20dB/decade). Per a few graphs I investigated, the knee is below 10K Hz. It is down ~5dB at 10K and ~11bB by 20K Hz (6dB/octave). This could be enough for the high frequency whine. For most, it will easier than playing with caps. It is simple, inclosed and cheap...

I am not looking at this as my solution to the low frequency noise. DC to DC convertors might be the solution and would account for the dollar difference between the two J&M filters (about the cost + markup of the converter). If I still need a high frequency filter, then I will use the above.

Currently the only time the low frequency noise is an issue is when I key (press the PTT) on the CB. I hear it and it is also being transmitted. The noise changes frequency with RPM.

This just got me thinking. There is 4Vdc on the mic line - most likely the source of the noise on transmission. Sure would be nice to remove the DC voltage - but that would be internal to the JMCB. Hum...:think:

...or maybe just a highpass filter on the mic line before the audio isolator...
 

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Discussion Starter · #10 ·
No not yet. Just ordered a dc to dc converter from Jamesco. $20.

But thanks for responding. In repling to you I thought of a few other things. Spent a few more hours in the hot garage with a scope. Got nowhere. But I did power the CB from a lab supply, to futher isolate the noise source. The net result was that the CB worked ok on the lab supply even with the motor running.
 

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No not yet. Just ordered a dc to dc converter from Jamesco. $20.

But thanks for responding. In repling to you I thought of a few other things. Spent a few more hours in the hot garage with a scope. Got nowhere. But I did power the CB from a lab supply, to futher isolate the noise source. The net result was that the CB worked ok on the lab supply even with the motor running.
Stupid question, I know, and one you've probably considered. But - if you're working indoors, any chance you're picking up that 60 Hz from fluorescent lights?

JayJay
 

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Discussion Starter · #13 ·
DC to DC helps with low frequency noise as shown in the picture attached.

Yellow = DC to DC output
Blue = RTW input

The high frequency content remains but the low frequency content is gone!!! The high frequency will be removed by the J&M filter I have or the line filter I ordered which is on a veeeeeery slow boat from China.

I could not listen to the CB as Jamesco send me the 24Vdc output (SKE15A-24) versus the 12Vdc output version (SKE15A-12) I ordered. :mad:

The SKE15A-12 is a 1.25 amp 12Vdc output with 9-18vDC input. 2 inputs and 2 outputs.

So it appears that the $20 DC to DC coupled with a $5 line filter can create a nice ~$25 noise solution. Beats the $159/135 solution from J&M...

KISS... :D

I will update once the correct part arrives...
 

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DC to DC helps with low frequency noise as shown in the picture attached.

Yellow = DC to DC output
Blue = RTW input

The high frequency content remains but the low frequency content is gone!!! The high frequency will be removed by the J&M filter I have or the line filter I ordered which is on a veeeeeery slow boat from China.

I could not listen to the CB as Jamesco send me the 24Vdc output (SKE15A-24) versus the 12Vdc output version (SKE15A-12) I ordered. :mad:

The SKE15A-12 is a 1.25 amp 12Vdc output with 9-18vDC input. 2 inputs and 2 outputs.

So it appears that the $20 DC to DC coupled with a $5 line filter can create a nice ~$25 noise solution. Beats the $159/135 solution from J&M...

KISS... :D

I will update once the correct part arrives...
J&M should be embarrassed.
 

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Discussion Starter · #16 ·
Attached are scope screen shots taken with the correct part.

Yellow = battery, output of ChargeGuard
Blue = output of DC to DC
Purple = output of J&M filter

First picture shows high frequency riding on top of lower frequency at the battery but the low frequency is NOT present at the output of either the DC2DC or J&M - just some high frequency stuff.

Second picture shows the high frequency on top of the lower frequency (all the yellow lines) but at a timebase to show the high frequency of the DC2DC and J&M outputs. I am not sure what this high frequency is but it isn't an issue for my application.

A test between the J&M, with the RTW engine running, and the CB in Effay's Jeep, the low frequency issue is gone! In general about 90% better than without the DC2DC.

:dance:

I'll add a few pictures for the wiring of the DC2DC shortly...
 

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Discussion Starter · #18 ·
Final configuration (for now anyway :wink:)

1st picture
Yellow = RTW Alternator output
Blue = Power at the input to the JMCB filter

I have a DC2DC connected to the RTW battery (via a ChargeGuard). Following the DC2DC is a power-line filter then the JMCB filter.

All other electronics (V1, V1 Bluetooth and MC200) are directly off the battery via the ChargeGuard.

2nd picture from bottom (front of RTW on left): MC200, ChargeGuard, DC2DC with power-line filter on top (directly soldered to DC2DC output pins).

All that remains is a bit of noise from the DC2DC switching as shown on the last picture. High frequency (150KHz+) and low amplitude (<100mV). This is not an issue for the JMCB or other electronics.
 

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Final configuration (for now anyway :wink:)

1st picture
Yellow = RTW Alternator output
Blue = Power at the input to the JMCB filter

I have a DC2DC connected to the RTW battery (via a ChargeGuard). Following the DC2DC is a power-line filter then the JMCB filter.

All other electronics (V1, V1 Bluetooth and MC200) are directly off the battery via the ChargeGuard.

2nd picture from bottom (front of RTW on left): MC200, ChargeGuard, DC2DC with power-line filter on top (directly soldered to DC2DC output pins).

All that remains is a bit of noise from the DC2DC switching as shown on the last picture. High frequency (150KHz+) and low amplitude (<100mV). This is not an issue for the JMCB or other electronics.
You should send a note to BMW showing how you fixed their problem. :stir:
 

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Discussion Starter · #20 ·
I'm sure they see it as J&M's problem! J&M has a solution if you order a new unit or want to pay $160/135. Not sure how well it works. But my $25 solution appears to do the job. Plus, it gave me a neat little project to use my new scope on. Bought a 4 channel, great price versus the availble 2 channels, thinking that I would typically use just 2. Used all 4 numerous times. Nice scope. Beats my 35+ year old CRT 20MHz B&K!!!
 
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