Phonohorn

3D modeling is similar to drawing in the sense that you must have a plan before you start.

Challenge:Take a small sound and make it bigger

The challenge is to make a circuit where a sound is output and then to design an acoustic amplifier to enhance the signal.

Part List for circuit

• Coin cell battery
• Coin cell battery holder
• Momentary push button
• Small speaker
• UM66T

The UM66 IC is a sound generator. The IC is a CMOS LSI designed for using in door bell, telephone and toy applications. The IC is preprogrammed to generate certain frequencies. When powered, the melody generator is reset and melody begins from the first note.

Circuit:

Design Questions

• What kinds of shapes might amplify our signal?
  

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• What do most wind instruments have in common?
  

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If you are starting with a cone:

• what kind of cone should you design? Perhaps a wide cone, one that goes from small to large
• What should the thickness of the material be? Why?
  

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• How do you enclose the electronic components?
  

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• How can you attach the horn to the enclosure?
  
  Drawing by Joseph Weissgold
  

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• Where should the button be placed?
  

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Soldering

Build the circuit so that you have an idea of how large your enclosure will need to be:

123D Design

45 minutes to model, 2-3 hours to print

The Phonohorn

1. Open Autodesk 123D Design and create a new project.
2. Select the Polyline tool. This tool allows you to create sketches with straight lines.
   
3. Change your view to Top View and lick on the Sketch Plane to specify the starting point:
   
4. Draw from left to right making this horizontal line somewher between 25mm and 40 (This will eventually be the widest part of the horn). To draw a line click the starting and ending points:
   
5. Move 50 mm down and 7m from right to left. When done press ENTER:
   
6. Select the Spline tool so that you can make a curve. Click on the first point to connect the lines then cick and drag to make the curve. Press ENTER when done:
   
7. Zoom in:
   
8. Select the Polyline tool and click on the end of the curve to connect the lines then move to the right by 2mm. Click to end the point. You can enter numbers in the field to specify the dimension:
   
9. Move down 1.75mm and click:
   
10. Move left 1 mm click and then connect the next line to the end of the 7mm segment:
    
11. Select the face and click Revolve:
    
12. Select the 50mm segment as the axis:
    
13. Enter 360 for the degrees of the rotation:
    
14. Click on the wide part of the horn and shell. Make the wall thickness 1.5mm:
    
15. Select the cirlce sketch tool and specify a starting point:
    
16. Create a circle with an 11mm diameter:
    
17. Extrude the sketch:
    
18. Click on the eye to temporarily hide the sketches:
    
19. Click on the Snap tool then the top face of the extrude cylinder:
    
20. Click on the face at the small end of the horn:
    
    
21. Click on ungroup to separate the snapped parts for editing:
    
22. Move the snapped cylinder in far enough to make a hole:
    
23. Click on Combine:Subtract :
    
24. Click on the horn:
    
25. Click on the cylinder:
    
    
26. Press ENTER:
    
27. Create a box 20mm x 2mm x 20mm:
    
28. Copy, paste and rotate the copied box by 90°:
    
29. Select combine and merge:
    
30. Select both boxes:
    
31. Press ENTER:
    
32. Click on the Snap tool and select the top face of the combined boxes:
    
33. Click on the rim of the horn:
    
    
34. Click on Combine:Subtract and select the horn first, then the boxes and press ENTER:
    
35. Create a rectangular sketch 40mm x 40mm:
    
36. Extrude the sketch:
    
    
37. select edges of the box, tweak, filet and chamfer:
    
38. Copy the maniputed box and paste and move twice:
    
39. Add a box so that you can get a flat plane:
    
40. Select the Polyline tool and click on the box. Then click two point across the objects close to the plane:
    
41. Click on Modify:Split Solid:
    
42. Select the first solid, then select the line to split the object:
    
43. Press ENTER:
    
44. Select the top part and delete it:
    
45. Repeat the process.Click on Modify:Split Solid. Select the second solid, then select the line to split the object:
    
46. Press ENTER:
    
47. Rotate so that you see the bottom:
    
48. Select the bottm face of the third object:
    
49. Shell with a 1mm wall thickness:
    
50. Select the Measure tool:
    
51. Click on both iside edges to measure the new width. WRite it down. Press ESC . Select the Measure tool again and measure the same dimension on the top face of the middle object. Write down this number as well:
    
52. Open a calculator and enter the first number minus .5 and divide that number by the second number. Divide what you want (the first number-.5) by what you have (the second number)to get the scale factor
53. Select the middle object and change by non-uniform scale. You want the height to end up around 1mm. Make sure the first object has a height of about 1mm. Use the Snap tool to attach object 1 and 2 together. Then select Combine:Merge:
    
54. Show sketches and measure this part of the sketch:
    
55. Create an ellipse whose diameter is 2x the measurement of the sketch+1:
    
56. Extrude the cylinder:
    
57. Snap the cylinder to the box:
    
58. Adjust the placement of the cylinder to make a hole, Then Select Combine:Subtract and remove the cylinder from the box:
    
59. Create the hole for the button:
    
60. Snap, adjust and subtract:
    
    
    
61. Export your parts and print