Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[cassf1]

Hi

Can anyone tell me a quiet ESC for graupner speed 700bb turbo running on 12v I have a mtroniks viper 25 in at the moment but the noise is very loud. Its ok in neutral but as soon as the stick is moved it starts and stays until its over powered buy the motors groan.

Thanks guys

[stallspeed]

The last time this subject came up,I was sitting at my workbench beside the computer with a loose motor,a similar speed controller and high revving motor. I switched on power,revved the motor and heard the low throttle screech.

The screech came from the paper that the motor was sitting on.When I picked up the motor the noise disappeared.All that is required is vibration dampening.

[jimtrellis]

The screech came from the paper that the motor was sitting on.When I picked up the motor the noise disappeared.All that is required is vibration dampening.

Screeching paper?? You can't be serious!

[Shipmate60]

Some of the earlier high frequency ESC's did make a high pitched hum when the motor was on low revs.
The newer ESC's however don't usually have the same amount of noise problem.

Bob

[stallspeed]

The screech came from the paper that the motor was sitting on.When I picked up the motor the noise disappeared.All that is required is vibration dampening.

Screeching paper?? You can't be serious!

Not the Sun or any right wing tabloid,just a piece of A4 photocopier paper that the motor was sitting on.

[craftysod]

I have a viper marine 15 that makes a hell off a racket,
changed for cheap china esc,no noise at all.
As Bob says the earlier batch of esc's suffered from high pitch scream

[Martin (Admin)]

Some of the older speed controllers are non "high frequency" (pulsed, controlled square wave, "chopper" or "crowbar") types.
 The old Hitec Sp-6/10A was a "voltage controller" if memory serves....

[stallspeed]

There is nothing wrong with your memory because I remember reading that before....it aint true.
The Hitec one just chops at the ~50Hz radio signal frequency.

[andygh]

I'm still using one of them there ancient Hitec jobbies, quiet as a mouse (or is it moose?)

[stallspeed]

The 6/10 can't handle a 700bb turbo  

The audible frequency is created by the motor windings vibrating at harmonics of the chopping frequency.
If the motor is directly bolted to an L-bracket then mounted in a boat hull then an effective musical instrument with one string is created.

Anti-vibration grommets or a patch of pvc foam in the right place will sort the problem.

[jimtrellis]

The audible frequency is created by the motor windings vibrating at harmonics of the chopping frequency.

So not the A4 paper, but a one-stringed musical instrument now?
I hope someone knows what you're talking about and can perhaps explain it to a techno-moron like me, because it makes little sense at the moment.

[andygh]

The 6/10 can't handle a 700bb turbo

No  , it's great on my 385 though

[cassf1]

Hi

Thanks for replies

Thanks Stallspeed this is not due to vibration though i have tried with motor out and starting up while holding just motor in hand
This marine viper 25 is new it about 5 weeks old.
Noise is very loud its not just a little buzz or i could live  with it
Anyone using a 700bb that makes no noise? What ESC

[Martin (Admin)]

Try ringing Mtronics, see what they say.
 I'm sure we're all interested to hear what they say.

[OMK]

I hope someone knows what you're talking about and can perhaps explain it to a techno-moron like me, because it makes little sense at the moment.

Take the line: "The audible frequency is created by...". Audible frequency meaning a range of notes detectable by human hearing.
And... "...vibrating at harmonics of the chopping frequency.". Harmonics meaning an exact multiple of the original frequency.
For instance, the note "A₄" on a piano is the string vibrating the air, back and forth, 440 times each second. 440 times per second is the resonant frequency (or just frequency) for that particular note.
Making sense so far?
Eight keys to the right of the A₄ is the A₅ key - the exact same note, but one octave higher. A5 vibrates the air 880 times each second, which an exact multiple of A₄... in other words, a harmonic. The next harmonic (the second harmonic) vibrates at exactly 1,760 times each second... and so on.
In order to vary the motor speed it's not just a case of adjusting the volts from zero to 12. Instead the voltage is sent at a constant 12 volts, but only in very short, very fast bursts'. The longer the burst = the faster the motor, vice-versa. Each burst is repeated over and over, sent at a steady and constant speed, usually anywhere around 10-thousand times per second and upwards -- the chopping frequency. This frequency is well within human hearing range so the whining sound you hear is the actual voltage pulse being switched on and off 10,000 per second. Some designers shift their chopping frequency way out of human audio range. The whines, farts and wheezes are stilll there only you can't hear them.
Stick all that lot inside a boat without at least some form of engine damping, and bingo... instant amplified chopping frequency.
I lifted this from Reader's Digest: "How to make yourself sound a real smart a**e.".

cass1: Mtronikcs 15A ESC?
Yuk!... bleugh!... spit-spit!
To have a stab at answering your question, try ACTion, or even Dawnmist.


Incidentally, 'Harmonic' is derived from 'harmony' (peace, man). When your motor is purring like a pussy is when it is said that your ESC is in harmony with your receiver, which in turn is in harmony with your transmitter. Ergo, the sound of that motor whine is music to these ears.
(Lifted that from Reader's Digest, and all).

[stallspeed]

The audible frequency is created by the motor windings vibrating at harmonics of the chopping frequency.

So not the A4 paper, but a one-stringed musical instrument now?
I hope someone knows what you're talking about and can perhaps explain it to a techno-moron like me, because it makes little sense at the moment.

Pass current through adjacent wires and there is a mechanical force of attraction between them.Switch the current on and off (alternating current)then the wires will vibrate at the alternating frequency.The higher the current the greater the force force with which they vibrate.- It's GSCE level science.If you want an idea of how strong the force is connect a 25metre drum of 1mm² to a 12 volt battery and the sudden switching surge of 25 amps is enough to make loosely wound turns jump.

Wires in motors vibrate with considerable force but with no amplitude,much like a trumpet mouthpiece or phonograph needle without a horn.

The noise comes from the motor being fed AC at audible frequency but even more so from anything the motor is affixed to that resonates.

[jimtrellis]

Pass current through adjacent wires and there is a mechanical force of attraction between them.Switch the current on and off (alternating current)then the wires will vibrate at the alternating frequency.The higher the current the greater the force force with which they vibrate.- It's GSCE level science.If you want an idea of how strong the force is connect a 25metre drum of 1mm² to a 12 volt battery and the sudden switching surge of 25 amps is enough to make loosely wound turns jump.

Wires in motors vibrate with considerable force but with no amplitude,much like a trumpet mouthpiece or phonograph needle without a horn.

The noise comes from the motor being fed AC at audible frequency but even more so from anything the motor is affixed to that resonates.

I'm sure this is all very impressive to those who are impressed by such things, but I get the feeling that the guy only wants to know if you have any practical experience of a speed controller which doesn't do this. I don't think he's in for a GCSE Science exam.

[malcolmfrary]

I get the feeling that the guy only wants to know if you have any practical experience of a speed controller which doesn't do this

From a practical point of view, the only controllers that are guaranteed to not produce motor noises are mechanical resistance controllers.  Sadly, they are not guaranteed to work as hoped for with any particular motor. 
Motors, like loudspeakers, consist of a lump of iron with wire wrapped round it that can move and a strong magnet that can't.  Both motor and speaker get fed with a varying amount of current.  It should therefore come as no surprise to find that they both make a sound in response to that varying current.  The only big difference is that the speaker has a paper cone attached to the moving part to move more air, the motor doesn't, un less you count the hull that it is fixed to.
A lot of the modern ESCs have shifted the whine beyond normal human hearing range or vary it with speed to minimise the problem, but, as stallspeed and PMK have both said, there may well be something in any particular motor to resonate with the waveform generated by the ESC.
If you know why a problem is happening, you can do something about it, if not you are just groping about hoping that magic will happen before the money runs out.

[cassf1]

Hi

Wow impressive fellas a science lesson and a music lesson from one post by the end of this i might be able to build a good musical instrument maybe even play a tune.

I'm not complaining though cause as malcolmfrary  says if you know what causes the problem might be able to fix before money runs out and
and this is the important part for me, so as jimtrellis says I'm hoping some one is using ESC with 700bb that does not make a sound.

Thanks