Passive Amp

This project we aimed to make a passive amp for our phones. We had to measure our phones with a pair of calipers and translate that how ever we wanted to start our design. Since my only speaker is on the top of the phone with the volume rocker being on the right side, I decided to make mine laying on it’s left side.

The base sketch was just a basic rectangle that was just slightly bigger than my phone to make room for the phone itself.



Next I made a line at 15degrees off the origin axis. I wanted to phone at a bit of an angle to make it like a desk clock.



Next I used a sweep to take extend the walls up and made an extrusion on the bottom to add a floor to the amp.



Next I created a sketch on the front face to make room for the screen and the speaker. To have everything align properly I needed to actually constrain it from the center of the floor. Looking straight at the face was like having the floor drop down at the from by 15 degrees.

Next I made the block for the megaphone portion and trimmed up the space for the phone a bit so that it would still align correctly. This part actually took two tries, the first print was off by quite a bit and I got a new attachment for my phone that made it thicker as well.



Next I made the block for the megaphone a little longer and added the hemisphere shape that I wanted to loft back to the oval for the speaker.



After some trial and error I was able to loft it. The big issue I was having is that it did not like that I was trying to pick a part of the geometry that was hidden under other surfaces. To fix this I made another extrusion for the speaker from the back and lofted the hemisphere to the new oval.

Next I added some fillets to the tops and a chamfer to the bottom. Most of the fillets were just there for style but the ones on the inside of the slot were made to keep any sharp edges from my screen. At this point the amp was functionally finished but I wanted to try and make it as a car mount, but that did not work in the end. The PLA plastic does not have enough rigidity to hold up a phone with a vent mount.

The Next set up modifications were all done to just the clip I tried to make. First I made a small circle on the back in the place that I thought would balance it out the best. I then made sections in the circle and extruded them with an outward taper. Next I extruded the circle potions on the outside as a cut with a slight taper as well. Finally I cut a profile into the side to have that side taper as well. The reason I did it this way was to get the taper in the space between the clips, I was expecting the PLA to be a bit stronger but it was too thin to support my phone. In the end the amp works slightly but there is a little too much space between the phone and the amp. I plan to put some padding in it to help with that and it was designed that way to start since it was supposed to be a car mount.


The part file can be found here:

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