Reimagining the Public Radio
Two weeks ago when the Public Radio exceeded its funding goal by wide margins on Kickstarter, Spencer and I knew that we had a new set of challenges ahead of us. Hand assembling these radios in our kitchen and walking them to the post office was no longer a viable option, and we knew we needed to figure out how to avoid spending all winter and spring hunkered over soldering irons. In all, this meant beginning to think about design for manufacturability (or DFM) - the creative re-engineering of a product to make it easier to manufacture at a larger scale.
The radio that will be delivered this spring to our 1,400 backers (and counting) will require a handful of changes. Some of these are related to DFM, and some are simple improvements that we want to make regardless. Over the past few weeks I’ve been quietly assembling a wish list for the new model. Here are the top four feature changes for the final hardware.
Frequency Set and Tracking
At the top of the list is designing an easy way to set each radio’s FM station before shipping it. The current model of The Public Radio uses a mechanically tuned FM IC by adjusting a small screw on the side of the radio. For smaller orders this worked fine, but for assembling thousands would be very time consuming. To make things easier we’ll be using a very similar, but digitally tuned version of our radio, and will set its station with a microcontroller housed on the PCB. In this case, after the PCBs are assembled we could place them on a jig, and program each station uniquely and electronically, before finishing the mechanical assembly and boxing the radios up. There’s a lot involved in those handful of steps, especially keeping track of each radio’s station as it were to come off of the line. Most likely, we would have to include some type of barcoding system on the PCBs themselves, in order to recognize each radio, set its station accordingly and box it up for the right customer.
Hidden UI, for Station Divorcees
One benefit of using a digital FM IC is that we can also sneak a small, somewhat hidden UI onto the bottom of The Public Radio. Remember, the Public Radio is about “radio monogamy”, it’s for those of us who listen to one station only. We got a lot of feedback however, from people who were worried about moving in the future and having to change stations. Just as your car’s digital clock might have a kind of hidden UI with a somewhat hard to find tactile switch, the Public Radio will have a similar switch hidden on its bottom, for the rare occasion when a listener would want to change to a new station. There won’t be any fancy LCD screen to tell you where you are in the frequency spectrum, just a one directional counter that increments through the FM range.
Along the way, Spencer and I have collected about a dozen portable radios that we like, and as for any FM listener reception is paramount. As a benchmark, we’re comparing The Public Radio against a military grade field receiver from County Comm. The quality is close so far, but we’re aiming for a solid win on the final hardware.
Increased Battery Life
Battery life is also extremely important to us. Early versions of the Public Radio got ~30 hours of runtime at medium volume, but we’re doing everything we can to improve that and are aiming for the final version to last 60–80 hours on a fresh set of AA batteries.
In all, these few changes mean that we’ll be significantly redesigning the inner workings of the Public Radio for the better. The overall look, however, will remain the same, and that means that any new design changes that we make — electronics or otherwise — will have to work around the physical locations of the speaker, volume knob, antenna, and battery clips.
Pricing for electronics is challenging in small quantities — things don’t really become affordable until you’re purchasing in bulk. Fingers crossed, this winter we’ll placing an order of ~2,500 units for our PCB assembly.
That being said, including the design changes on this wish list, our goal is to keep our entire BOM with electronics assembly at ~$15.00 per radio — a good challenge but not too impossible.