Passive Phone Amplifier

I have been looking at various Passive Amplifier Designs on line and trying to find one to make. Using my CNC software (Carbide Create), I designed the a Transistor Radio style Amp. I have uploaded a SVG file for those who wish to make one. Unfortunately I was unable to upload the Carbide create file as it is not supported by Instructables.

1" x8" x 24" Wood (in my case I chose Walnut)

1/4" Dowel Rod

Soda Can

Wood Glue

Stain (optional)

Spray finish, Lacquer or Polyurethane

CNC Router

CNC Router Bit - 1/8" Compression Bit

Handheld Router and Table

1/4" Half Round Router Bit

Double sided tape

Sandpaper - 150, 240 & 320 grit

Start by designing the radio in Carbide Create. For those familiar with Carbide Create it was a fairly easy task as it was just a series of rectangles and circles. Then use the Fillet, Boolean and Linear Array tools while laying out and complete the design.

The toolpaths were created as follows

• Pocket toolpath for the Speaker Holes, Knobs, Display background & Station Number.
• Drill toolpath for the grill holes and guide holes.
• Contour toolpath for the outlines.

When the design is completed simulate it in Carbide Create or your Cadd program to double check the design. Tweak the design until you are satisfied, then save the file.

Now it is time to cut the radio on the CNC router. In this case a Shapeoko CNC was used. The file may have to be broken up into several individual files if your CNC table will not cut 23" wide material. Start by securing the wood to the CNC router bed using Double Sided tape. With the wood secured, set thee zero point on the router and began cutting.

Prior to final assembly, use a 1/4' half round router bit in a table mounted Router to round over the front, of the front side, the back of the back side and both sides of the inside of the handle. .Sand the front and back faces of the Radio starting with 150 grit end ending with 320 grit. With the initial sanding complete dry fit all the parts to insure they all line up correctly.

Start by cutting the 1/4" dowel into two 1" pieces. Glue and insert the dowels into the holes in the back side. Cut the bottom off of the soda can leaving about 1/4" on the side. Insert the soda can bottom in the groove in the back side but do not glue it. Apply glue to the back side of the middle piece, align the dowels and assemble the two pieces. Use clamps to hold the two pieces tight till the glue dries. When the glue is dry remove the clamps. Apply more glue to the front side of the middle piece. Align the front piece with the middle and clamp tightly taking care to keep the sides aligned smoothly. If you desire to paint the knobs a different color do not glue them in place yet. Allow glue to dry.

The assembly can now be sanded on the sides to insure smooth transition between the 3 sections.

Stain and finish the radio as desired using stain, varnish, lacquer, etc. as desired. In this case Lacquer was used on the radio and black paint on the knobs. If the knobs were painted separately, they can be glued to the side when the finishing is complete.

Options for futures builds are as follows:

• No handle on the top - Most table top radios don't have handles.In addition. this will make the sanding after gluing must easier.
• No Knobs
• Make Knobs from larger dowels
• Drill a hole ion the back side to allow a battery cable top be inserted
• Make the slot for the phone a little deep to allow the phone to sit in deeper
• Use a round over bit in the CNC vs router the front and back separately