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Coolbank Stuart Whine--any solutions?
Posted: Sat Feb 08, 2025 7:28 pm
by ColemanCollector
Probably my biggest disappointment with the Coolbank Stuart is the annoying whine as soon as it moves.
Any solutions out there? I'm assuming the ESC's are the culprit?
As a frequent driver of old bangers during my lifetime, the solution for a noisy transmission was "turn up the radio!", but that's not even an option for the Stuart given Coolbank's lacklustre sound amplifier. Help, please!
Mike.
Re: Coolbank Stuart Whine--any solutions?
Posted: Sat Feb 08, 2025 8:50 pm
by Herr Dr. Professor
I would guess that the whine comes from the gearbox, not the ESCs, but I could be wrong. I did put a 4 ohm speaker in my little M5 because I had one around. It did bring up the engine sound volume a little bit, and I do think the engine sounds are pretty good. (Of course, when money is tight, I suddenly become more satisfied with what I already have.
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Re: Coolbank Stuart Whine--any solutions?
Posted: Mon Feb 10, 2025 8:51 am
by Estnische
Check for Poms. Downunder we usually find that is the cause of annoying whining sounds. (Grabs helmet and ducks to bottom of trench>>>
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Re: Coolbank Stuart Whine--any solutions?
Posted: Mon Feb 10, 2025 2:18 pm
by ColemanCollector
Funny, after I wrote that post I had an irresistable urge for jellied eels, bubble and squeak, and some spotted dick. Instead, I had a poutine, back bacon on a bun, followed by some tarte au sucre. Felt much better!
So, fiddled with the Stuart a bit more. With motors disconnected, no whine. And by whine I mean a high-pitched sound like when a heart monitor flatlines (I guess it's really the patient...). With motors plugged in, the whine starts as soon as there's motor movement with low gear speed. No increase or change as speed increases.
So it's not gear whine, but electrical noise from the motors(?). I'll try the usual motor noise reducers like another one or two more capacitors per motor, and twisting the motor leads. Hoping a bit of sound deadener over the motors and a better speaker/speaker venting will help hide the whine. I have a 4ohm speaker Prof, so I'll give that try as well.
Mike.
Re: Coolbank Stuart Whine--any solutions?
Posted: Mon Feb 10, 2025 3:57 pm
by Exhibitedbrute
The speaker is truly crap but when I get round to mine I plan ripping everything out and starting again
Re: Coolbank Stuart Whine--any solutions?
Posted: Mon Feb 10, 2025 9:52 pm
by tankme
ColemanCollector wrote: ↑Mon Feb 10, 2025 2:18 pm
Funny, after I wrote that post I had an irresistable urge for jellied eels, bubble and squeak, and some spotted dick. Instead, I had a poutine, back bacon on a bun, followed by some tarte au sucre. Felt much better!
So, fiddled with the Stuart a bit more. With motors disconnected, no whine. And by whine I mean a high-pitched sound like when a heart monitor flatlines (I guess it's really the patient...). With motors plugged in, the whine starts as soon as there's motor movement with low gear speed. No increase or change as speed increases.
So it's not gear whine, but electrical noise from the motors(?). I'll try the usual motor noise reducers like another one or two more capacitors per motor, and twisting the motor leads. Hoping a bit of sound deadener over the motors and a better speaker/speaker venting will help hide the whine. I have a 4ohm speaker Prof, so I'll give that try as well.
Mike.
It's ESC whine. The ESC portion of the control board emits a sound frequency from the MOSFETs. That's why Clark advertises ultrasonic FETs on his site as they don't emit sound in the audible spectrum. Most ESCs from the 70,s, 80's, and 90's sounded that way. Ultrasonic MOSFETs are now cheap enough to be used in most electronics, but my guess is that Coolbank saved a tiny amount of money by using standard MOSFETs on the board.
Re: Coolbank Stuart Whine--any solutions?
Posted: Mon Feb 10, 2025 11:21 pm
by Tiger6
Motors will whine and buzz when subjected to a PWM signal from the ESC's - especially the small can motors in the Stuart.
Re: Coolbank Stuart Whine--any solutions?
Posted: Tue Feb 11, 2025 12:19 am
by Herr Dr. Professor
So I went to Wikipedia's entry on "MOSFET." There are MOSFETs, MOS-FETs, MOS FETs, MOS transistors. You can just have a FET or be a MISFET or even get IGFET.
Wow, this clarifies why every Tuesday the other modelers ask why it takes me so long to do simple modifications on electronics. Then there are AM, PM, and even PWM. Maybe I ought to stick to RTR.
"...the metal–oxide–semiconductor field-effect transistor (MOSFET, MOS-FET, MOS FET, or MOS transistor) is a type of field-effect transistor (FET), most commonly fabricated by the controlled oxidation of silicon. It has an insulated gate, the voltage of which determines the conductivity of the device. This ability to change conductivity with the amount of applied voltage can be used for amplifying or switching electronic signals. The term metal–insulator–semiconductor field-effect transistor (MISFET) is almost synonymous with MOSFET. Another near-synonym is insulated-gate field-effect transistor (IGFET)."
https://en.wikipedia.org/wiki/MOSFET#Operation
Re: Coolbank Stuart Whine--any solutions?
Posted: Tue Feb 11, 2025 1:34 am
by ColemanCollector
Tankme wrote:
[/quote]
It's ESC whine. The ESC portion of the control board emits a sound frequency from the MOSFETs. That's why Clark advertises ultrasonic FETs on his site as they don't emit sound in the audible spectrum. Most ESCs from the 70,s, 80's, and 90's sounded that way. Ultrasonic MOSFETs are now cheap enough to be used in most electronics, but my guess is that Coolbank saved a tiny amount of money by using standard MOSFETs on the board.
[/quote]
Thanks for the confirmation! Like HDP, I go for most of my life never having heard of a MOSFET, and then WHAMO! Twice in just a week or two.
So I guess the best approach on the Stuart is to turn it up to eleven! Mini amplifier is in the mail.
Mike.
Re: Coolbank Stuart Whine--any solutions?
Posted: Tue Feb 11, 2025 1:34 am
by ColemanCollector
Double post...
Mike.