I wanted to find an equation that calculated a whistle's frequency based on its cavity dimensions. I hypothesized that volume is a factor, but length is more important for frequency, while the cross-sectional area is responsible for amplitude. I printed a set of eighteen whistles with two body styles. Most of the lengths overlap, but I wanted to record frequencies for enough devices to draw a conclusion before I attempt a specific frequency based on the equation.
I graphed the different whistle sizes and measured their frequencies. My hypothesis about cavity size lowering frequency was correct, but my other guess about length being a significant influence was disproved. Volume seemed the critical issue, so that I can reconfigure the shapes to something more convenient.
My TuningWhistles emitted tones, but they were not reliable. I wanted a way to control their frequency precisely, so I installed a threaded insert that let me reduce the cavity volume by inserting a bolt. I could not detect any difference, so I modeled an L-Shaped whistle with a solid portion that I could drill from the inside to increase the cavity volume.
The L-shaped whistles with the drillable section were a lot of time and effort for a toy, so I gave up on the idea. Cylindrical whistles would use plastic more efficiently, so I revised the design to use circles. The prints were lower-pitched than the rectangular ones because of the larger interior. The first two whistles had an internal diameter of 19mm and 24mm.
I completed the TuningWhistles project by making four large black whistles for the low tones of the DTMF frequency range, and four slim white whistles for the high frequencies. I randomly paired them up and shot a demonstration video.
DM Ray came back on the show to promote his upcoming Kickstarter for the fantasy comic The Madcaps. He selected Legend (1985), and we were surprised to find it less problematic than we had assumed, but also more confusing than we remembered. The script was the product of two men writing it for years, and in the process, they forgot to include all the world-building we needed to realize their vision.
The rest of the summary posts have been arranged by date.
First time here?
Completed projects from year 1
Completed projects from year 2
Completed projects from year 3
Completed projects from year 4
Completed projects from year 5
Completed projects from year 6
Completed projects from year 7
Completed projects from year 8
Completed projects from year 9
Completed projects from year 10
Completed projects from year 11
Completed projects from year 12
Disclaimer for http://24hourengineer.blogspot.com and 24HourEngineer.com
This disclaimer must be intact and whole. This disclaimer must be included if a project is distributed.
All information on this blog, or linked by this blog, is not to be taken as advice or solicitation. Anyone attempting to replicate, in whole or in part, is responsible for the outcome and procedure. Any loss of functionality, money, property, or similar, is the responsibility of those involved in the replication.
All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.
Comments to the blog may be utilized or erased at the discretion of the owner. No one posting may claim property or assets based on their post.
This blog, including pictures and text, is copyright to Brian McEvoy.
 |
| Eighteen whistles with different volumes |
I graphed the different whistle sizes and measured their frequencies. My hypothesis about cavity size lowering frequency was correct, but my other guess about length being a significant influence was disproved. Volume seemed the critical issue, so that I can reconfigure the shapes to something more convenient.
 |
| Graphs showing the measured frequencies and dimensions |
My TuningWhistles emitted tones, but they were not reliable. I wanted a way to control their frequency precisely, so I installed a threaded insert that let me reduce the cavity volume by inserting a bolt. I could not detect any difference, so I modeled an L-Shaped whistle with a solid portion that I could drill from the inside to increase the cavity volume.
 |
| Heat set insert in a 20mm whistle |
The L-shaped whistles with the drillable section were a lot of time and effort for a toy, so I gave up on the idea. Cylindrical whistles would use plastic more efficiently, so I revised the design to use circles. The prints were lower-pitched than the rectangular ones because of the larger interior. The first two whistles had an internal diameter of 19mm and 24mm.
 |
| Internal view of cylindrical whistle |
I completed the TuningWhistles project by making four large black whistles for the low tones of the DTMF frequency range, and four slim white whistles for the high frequencies. I randomly paired them up and shot a demonstration video.
Testing four pairs of tuning whistles
DM Ray came back on the show to promote his upcoming Kickstarter for the fantasy comic The Madcaps. He selected Legend (1985), and we were surprised to find it less problematic than we had assumed, but also more confusing than we remembered. The script was the product of two men writing it for years, and in the process, they forgot to include all the world-building we needed to realize their vision.
Critical Affection: Legend (1:21)
The rest of the summary posts have been arranged by date.
First time here?
Completed projects from year 1
Completed projects from year 2
Completed projects from year 3
Completed projects from year 4
Completed projects from year 5
Completed projects from year 6
Completed projects from year 7
Completed projects from year 8
Completed projects from year 9
Completed projects from year 10
Completed projects from year 11
Completed projects from year 12
Disclaimer for http://24hourengineer.blogspot.com and 24HourEngineer.com
This disclaimer must be intact and whole. This disclaimer must be included if a project is distributed.
All information on this blog, or linked by this blog, is not to be taken as advice or solicitation. Anyone attempting to replicate, in whole or in part, is responsible for the outcome and procedure. Any loss of functionality, money, property, or similar, is the responsibility of those involved in the replication.
All digital communication regarding the email address 24hourengineer@gmail.com becomes the intellectual property of Brian McEvoy. Any information contained within these messages may be distributed or retained at the discretion of Brian McEvoy. Any email sent to this address, or any email account owned by Brian McEvoy, cannot be used to claim property or assets.
Comments to the blog may be utilized or erased at the discretion of the owner. No one posting may claim property or assets based on their post.
This blog, including pictures and text, is copyright to Brian McEvoy.
Comments
Post a Comment