Much like the tone of the 'singing' when using address 0 to run a DC loco on DCC.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Overmod Mark R. The buzz doesn't come from the speaker. The noise comes from less than perfect tolerances in the motor creating a high frequency buzzing during the BEMF sampling period. I did not understand Tom's original observation to refer to 'buzzing' of any kind: he cited specific musical tones and even gave their scale equivalents. I'm certainly familiar with AC-drive locomotives (at full scale) producing musical tones as they accelerate, but this surely isn't from components equivalent to laminated-field or other DC motor components being subjected to modulated current.
Mark R. The buzz doesn't come from the speaker. The noise comes from less than perfect tolerances in the motor creating a high frequency buzzing during the BEMF sampling period.
I did not understand Tom's original observation to refer to 'buzzing' of any kind: he cited specific musical tones and even gave their scale equivalents. I'm certainly familiar with AC-drive locomotives (at full scale) producing musical tones as they accelerate, but this surely isn't from components equivalent to laminated-field or other DC motor components being subjected to modulated current.
Yes, the "buzzing" or whatever you want to call it DOES change in frequency as would be expected during BEMF sampling periods and a higher PWM with each speed step increase.
Mark.
¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ
Mark R.The buzz doesn't come from the speaker. The noise comes from less than perfect tolerances in the motor creating a high frequency buzzing during the BEMF sampling period.
The buzz doesn't come from the speaker. The noise comes from less than perfect tolerances in the motor creating a high frequency buzzing during the BEMF sampling period. Turning the BEMF off entirely completely eliminates the buzz. The noise if even there with the Loksound 4 version non-sound decoders.
Is it possible that there is some inductive coupling between the motor power and the speaker leads that is receiving some effective harmonic of the waveform? Rerouting conductors or harness layout might help if so.
The new Loksound5 decoders have eliminated that BEMF buzz entirely. I've been replacing my noisier Select Direct decoders with the Loksound5 Next18 micro (same V4 sound file) and the buzz is gone. The old Select goes into engines that have tighter motor tolerances and don't exhibit the buzz as noticeably.
rrinkerAlso, that is the sheet that came with the new RS-3 I got a month ago - except mine has a Loksound v5
Rapido has also stumbled in some of their recent documentation refering to a Select when the locomotive actually has the V5. For anyone not familiar with ESU decoder model designations they may have some difficulty.
Good Luck, Ed
Note there is a section in there on BEMF noise. Also, that is the sheet that came with the new RS-3 I got a month ago - except mine has a Loksound v5 and it';s not CV48 to change the horn/prime mover/bell, nor is the value for CV124 applicable to a V5, the value of 16 controls some function output, not variable frequency BEMF.
I like to have this Atlas handout handy to refresh my memory on ESU Select options:
http://download.atlasrr.com/DCC/Cheat%20Sheet%20for%20%20Atlas%20Gold%20Series%20Diesels%20with%20LokSound%20Select%20v15.pdf
Hz my ears!
Ω+y Ed
Note the values used for Loksound 5 are different - the value of 4 is still for the prime mover delay, but 16 is not related to the BEMF. My new Atlas RS-3 has a v5 decoder in it.
Annoying the instruction sheets included witht he model do not reflect this - for example, the horn selection CV is different, the instruction sheet shows the v4 (or maybe it's Select) option, which is not the right CV to change on the loco. Usign the V5 instructions and the Alco 244 project file information for the V5, I was able to figure out which value was needed for the M3RT1 which is what horn was used on my prototype (even though Atlas still sticks on a hood mounted single note hooter).
Mark R.Try setting CV124 to a value of 20, then do the Auto BEMF setting. If the loco pauses too long before moving off for your tastes, set CV124 to 16 instead.
Thanks, Mark! That did the trick!
I ended up settling on a value of "16" for CV124. However, now that I see from the Loksound manual what the different bits adjust, I may play around with that value a little bit.
I ran the automatic motor turning feature as you suggested and that improved the motor control at speed step 001. The value for CV124 was set to "4". (The default is "24") That meant that the adaptive regulation frequency was enabled rather than the constant regulation frequency.
Anyhow, thanks for the suggestion, Mark.
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
Crandell,
The audible humming is with F8 muted. With F8 engaged I don't hear it as much for obvious reasons but it's still there. The motor frequency is set to 40kHz (vs 20kHz)
Tom, don't roll your eyes....does muting accomplish anything? This is absolutely something to do with drive freq or BEMF...?
That really doesn't address or answer my question. I neither opened nor removed the shell from the chassis but only reset it. It seems it has more to do with the BEMF since the humming disappeared when it was turned off. And, prior to the reset, the BEMF was engaged but there was no humming emanating from the Loksound decoder/locomotive.
Try setting CV124 to a value of 20, then do the Auto BEMF setting. If the loco pauses too long before moving off for your tastes, set CV124 to 16 instead.
Aside from fiddling with the CVs, I did discover something that greatly reduces the "buzz". What I found what that the plastic motor cradle (on Atlas engines) touches the inside of the shell and the shell amplifies the noise. I cut the sides off both the front and rear plastic cradles so it was now the same width as the motor itself. With the cradle no longer contacting the shell, the buzz was reduced almost to the point of not being heard.
On a couple Atlas engines, I took it a step further. I cut both screw mounts completely off the bottom of the motor cradle, then installed the motor / cradle using a blob of silicone. This eliminated the solid mount to the chassis (which also transmitted the buzz to some degree) and gave the motor a "softer" insulated mount from the chassis.
Both those modifications reduced the buzz to the point of having to put your ear right up to the engine to still detect it.
This evening I reset the Loksound Select decoder in my Atlas RS-3 road switcher and reprogrammed it. It was a very quiet decoder before the factory reset. Now it hums noticeably.
I've heard a similar hum on a few TCS decoders but only at low speeds and it quickly dissipates after speed step 010 or so. The hum from the Loksound Select, however, is more prolonged and never goes away.
Here's the breakdown of the hum in Hz and the equivalent note value...
Speed step range | frequency:
Not surprising, when I turn off BEMF the hum goes away. I also have and had DC-mode turned off.
So, what would change to cause the BEMF to hum noticeably when it was quiet before? I also performed the automatic motor turning feature but the humming persists.
Thanks,