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Old Jun 28, 2005, 06:00 PM
KSU Flyer's Avatar
Manhattan, Kansas, United States
Joined Oct 2001
3,503 Posts
engine sound generator for electric models

Guys,

I don't know if this is way out there or not, it may have already been dicussed here too. I'm posting this based on some conversation that got going over in the parkflyer forum, and has me a bit interested.

Anyway, one of the things I miss most about my slimer days is the sound of a nice 4 stroke engine on my plane. I just liked the realism it added to my models. So, as the title suggests...How could this be done electronically.

My preference as well as others would be to have a way to have different sounding engine tones, emulating the sounds of the different full scale engines. Especially and old radial style engine. What would also be very neat is to have the sound change with throttle stick position.

One obvious restriction would be how loud could make the sound. All this would be for not if we couldn't hear it while the plane was flying around. However, most of the outrunner style motors are next to completely quiet, so you wouldn't be fighting that. My other thought is that some of these darn cell phones have such loud ringers/speaker which play sound etc., so the miniature speaker shouldn't be a limitation. For instance take a look at this link.

http://www.regalusa.com/high_power_m..._speakers.html

Ok, thats probably the simple part. We need a way to recreate the audio signal, and drive the speaker. So, I found this.

http://www.vlsi.fi/vs1011/vs1011.shtml

This link provides take you to a "Very Low power MP3 Audio Decoder IC". This would allow someone to record an engine sound of your choice, upload it to the IC's RAM, then play it. However, that may or may not work for varying throttle positions. It may work out however that as you monitor the PWM signal from the throttle stick that you could play different MP3 tracks. That is if 7.5 Kb is enough space to store much of a looping MP3.

I dunno, maybe thats out there a bit...somebody bring me back to earth.

-Mike
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Old Jun 28, 2005, 06:04 PM
KSU Flyer's Avatar
Manhattan, Kansas, United States
Joined Oct 2001
3,503 Posts
Just found this, so maybe there is already an off the shelf solution?

http://www.phoenixsound.com/index.html
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Old Jun 29, 2005, 02:12 AM
Registered User
Johannesburg , South Africa
Joined Jul 2004
151 Posts
Hi Guys

Possibly the easiest solution is to use a CMOS circuit similar to this one. Change the cap between 220pf to 1f to operate at a lower frequency and use the voltage from the motor to drive this circuit as it is voltage sensitive, low voltage = low beeps, higher voltage = high beeps. Use a Piezo sounder for the sound output.

Mark
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Old Jun 29, 2005, 02:19 AM
Registered User
Johannesburg , South Africa
Joined Jul 2004
151 Posts
oops

Opps
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Old Jul 05, 2005, 08:53 PM
Registered User
Ottawa
Joined Feb 2004
112 Posts
or, you could attach asmall piece of cardboard to the nose where the prop will flip it, just like I used to do with a baseball card in my bike's spokes back in the days that a bike was a new invention
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Old Aug 11, 2005, 09:41 AM
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Ekim's Avatar
S. Jersey, US, the 51 state
Joined Oct 2004
289 Posts
well........ as for the space issue..... if you use an ATMEL microcontroller as I am for my combat system, you buy extra flash chips whic can be read by the main controller
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Old Aug 11, 2005, 10:30 AM
Outcast outlaw
As far away from RCGroups and the AMA as possible!
Joined Aug 2004
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This is the combination I've been working on:

http://store.qkits.com/moreinfo.cfm/FK928
$20 plus shipping.

http://www.regalusa.com/high_power_m..._speakers.html
Minimum order of 500 at $3.49 each. I currently have two free samples.

I've got a .wav file of some pretty darned good gunfire. I tried uploading it several times, but it's too big (even when I zip it). I'm more interested in gunfire than engine noise...

EDIT --> According Qkits, the FK928 outputs just less than 400 milliwatts. Checking the spec sheet for the RH-16-E speaker (this is what I have two of), .3 watts (nominal) will give me 73 decibels of sound. A vacuum cleaner makes a sound of 70 decibels, so it should be pretty loud!

The real question is, will you be able to hear it at a distance, over the sound of the motor and prop?
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Old Aug 12, 2005, 04:41 AM
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Acetronics's Avatar
Le Treport, France
Joined Jun 2004
1,398 Posts
Hi, Guys

Do you have a little idea of the amplifier power and speaker weigh you need to make something "ear-able"

Seems the answer is NO ...

Alain
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Old Aug 12, 2005, 06:49 AM
Registered User
Manila, Philippines
Joined Jul 2004
1,203 Posts
I guess, its easier just to install a real Glow Engine, I love to hear the sound of Four Stroke engine.

How about a small noise maker (Thin Sheet Plastic, that make noise when propeller hit it) and install a small buffle to make sound like a four-stroke engine......I use to have a small toy gun that use this principle.

Ellion
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Old Aug 12, 2005, 08:25 AM
"MAYONNAISE"
Acetronics's Avatar
Le Treport, France
Joined Jun 2004
1,398 Posts
I think a model of the little gadget mounted aboard the JU 87 ( Diving bomber ) could be the most realistic sound available ... ( siren activated by a propeller )

seriously, an integrated circuit( HT 2830 or 2844 ??? ) was recently sold, which animated the child's toys ... Helis, Fighters, etc ...

see here : http://www.temp.eleinmec.com/issue9.htm

Birds and animals too, with different chip suffixes !!!

Alain
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Old Aug 12, 2005, 09:33 AM
Outcast outlaw
As far away from RCGroups and the AMA as possible!
Joined Aug 2004
6,601 Posts
Quote:
Originally Posted by Acetronics
Hi, Guys

Do you have a little idea of the amplifier power and speaker weigh you need to make something "ear-able"

Seems the answer is NO ...

Alain
Actually, with an electrical engineering degree, and 15 years of work experience, I DO understand how to make something "HEAR-able". But thanks for asking...
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Old Aug 12, 2005, 01:25 PM
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Acetronics's Avatar
Le Treport, France
Joined Jun 2004
1,398 Posts
Quote:
Originally Posted by Red 61
Actually, with an electrical engineering degree, and 15 years of work experience, I DO understand how to make something "HEAR-able". But thanks for asking...
That was not really a question ... I've had a good experience with my model boats ...

Alain
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Old Aug 12, 2005, 04:51 PM
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vintage1's Avatar
East Anglia, UK
Joined Sep 2002
29,689 Posts
Quote:
Originally Posted by Acetronics
Hi, Guys

Do you have a little idea of the amplifier power and speaker weigh you need to make something "ear-able"

Seems the answer is NO ...

Alain
Yes. A lot less than it takes to power an aerplnae, and, depending on the frequencies you want to reproduce, between impossibly heavy to really insiginifcantly light...
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Old Aug 12, 2005, 05:30 PM
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Gary Warner's Avatar
Dallas Tx USA
Joined Apr 1999
2,505 Posts
My idea for a motor noise generator.

Take a pager motor and attach a wire across the motor shaft (like a prop) and put lead (solder) "balls" on the ends of the wire. Place the motor assembly inside a "drum" so that the balls take a glancing blow at the surface of the drum. Use a ESC to control the RPM's of the motor, or if using a brushed motor, use a tapped motor voltage.

As the voltage increases, the pager motor runs faster. It could be fine-tuned to match scale RPM's (450-2600).

And, NO, I don't use recreational drugs.

Gary
--
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Old Aug 12, 2005, 08:19 PM
doobie doo
skewbe's Avatar
Joined Mar 2005
221 Posts
If you are going to generate noise electronically to sound like a slimer, may I ask that you use headphones?

I think some of the geared motors make a pretty cool sound fyi.
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