MAS.863: How To Make (Almost) Anything


Final Project

Fab Radio w/ Found Materials

This radio, created in collaboration with Dana Gordon, is an experiment in the fabrication of consumer electronic products. The frame is made of press-fit, laser-cut plywood and covered with thin front and back face-plates. Any found material can be used for the fabric, which covers the top of the radio and the speaker. Here, we've used a souvenir from a trip to India. The electronics, including knobs and power jack, are mounted on a single circuit board at the base of the radio. The whole product is designed to be easily and quickly assembled from fabricated components.

There are numerous examples of individuals producing circuit boards or electronic kits in quantities of hundreds or thousands, but few target a general audience. By carefully designing the appearance and construction of the radio's case as well as its electronics, we have arrived at a consumer product that can be manufactured in similar quantities. With access to a laser cutter, an individual could manufacture and sell this radio on a scale sufficient to provide significant income. We hope that this example will help inspire the creation of fabrication-based, consumer electronics small businesses.


Early design sketches for fab-able products made using found materials. Sketch by Dana.
My notes from Neil's suggestions for doing demodulation of AM radio signals in a microcontroller. The antenna would be differentially connected to the ADC, with a voltage divider (pull-up and pull-down resistor) on one side to keep the signal between the rails. By using a low analog reference (AREF) voltage and the 20x internal gain, it should be possible to distinguish the radio waves. By sampling at the frequency to be tuned (by configuring a timer to overflow at the right rate), and alternately adding and subtracting readings, you could, in theory, cancel out the carrier wave. I'm not convinced the ADC can sample fast enough, and I also worry that the resulting data will depend heavily on the phase of the samples (which will likely drift over time). Also, I don't know how you avoid crosstalk from other AM radio stations, whose carrier frequencies are similar to the one you want.
Prototype of the interior frame for the radio. A found soft material (e.g. old t-shirt or map) will be stretched over the curved surface. The frame is held together with press-fit struts. The prototype is in cardboard, but the final object will use plywood or another hard material.
A prototype of the radio structure. The speaker will fit in the large circle, to be covered by another found soft material. The two smaller holes are for the volume and tuning knobs.
Prototyping mess. It receives and plays radio! It's a chance for me to test the advantages and disadvantages of milled PCBs vs. breadboarding vs. commercial board. The red guy is a Seeeduino, which I used because it can run at 3.3V (needed for the TFM-1010).
Breakout board for the TFM-1010 FM receiver module from SparkFun: fmbreakout.sch, fmbreakout.brd. This uses the Airoha AR1010 IC and can be controlled via I2C (TWI) from a microcontroller.

Simple audio amplification circuit using an LM386 (built-in 20x gain) w/ a 0.1 uF capacitor to remove the DC current from the incoming signal. Will be replaced with a milled PCB. I omitted the volume potentiometer for now, so it's really loud. There's also lots of static, but that's probably because the new Media Lab building is a big metal box.

Gluing my old map to the curved cardboard radio frame.
Glueing the paper speaker cover to the back of the cardboard front panel.
Finished prototype and tools.

Redesigning the structure. The front panel has bigger holes that fit the potentiometers. The front frame has a hole that's slightly smaller than the speaker and will hold it in place.

Download: radio4.svg (Inkscape).

Two new boards: one for the ATmega88 and the other for the amplifier (LM386). I've added a volume knob and another potentiometer than can be used for tuning.

Download: atmega88-2.sch, atmega88-2.brd
Download: amplifier2.sch, amplifier2.brd

The guts of the radio. This will all be combined onto a single PCB.

Integrating the three circuits into one PCB. The potentiometers should align with the holes in the front panel, and the power jack with a hole in the back.

Download: combinedsmall.sch, combinedsmall.brd

Soldering components onto the combined board.

Laser-cut 1/4" plywood in a pressfit structure for the radio frame.

Download: radio-0.25-inch-plywood.svg, strut-0.25-inch-plywood.svg (Inkscape)

Dana glueing the found material onto the frame.
The inside of the radio with speaker in place.
Last minute surgery after soldering the speaker to the board.
Souvenir from my trip to India, now in a useful form.