vibrant violet vulpes

LED Badges — First PCB

I finished creating the first PCB for the prototypes and it seems to mostly work.

As of right now I'm still having issues with charging through the Micro USB port, I believe something is wired incorrectly. Additionally it seems to discharge the battery overnight, suggesting current is still running somewhere it shouldn't be while powered off.

PCB with components soldered on

While the soldering job isn't very pretty, it does seem to do the job. You can also see the holes in the board are shifted slightly. That was due to me not properly aligning the board when engraving it.

It's incredibly bright

When evaluating the batteries I got previously, it seems like they only store around 250mAh instead of the advertised 350mAh. While this isn't great, it's not a downgrade from the 240mAh batteries I was using before. I'm going to continue evaluating and see if the one I tested was defective, if my battery charger just isn't that accurate, or if the batteries really are that much lower capacity than advertised.

In order to properly test it, I need to 3D print the case for them. While the board was designed to make it easy, it will still take some work to find the smallest possible design that still can easily hold everything. It is designed so that the switch will be directly exposed, but the buttons will have a printed part covering them.

I also need to figure out how to design the case to most securely hold the acrylic. Hot glue was good for a prototype, but after sitting in my backpack on the flight home, it detached itself.

Next up: resolving circuit issues and designing a 3D printable case.


At times, it's useful to get information from people reading a blog post. However, requiring users to visit another site, potentially deal with advertisements or creating accounts, or other annoyances greatly drives down the number of people willing to answer a quick question.

In an attempt to make it easier for users to quickly respond, I've created a small web app called Peppershrike.

Here's an example of how it works:

It's incredibly quick and easy to use and doesn't require users to visit any other sites or fill out any other information. It's easily themeable to fit into any site. And it's free and open source software!

All you have to do is create a div to contain the survey and include a small JavaScript snippet. Here's an example, using the same code for the survey above.

<div class="peppershrike" data-id="1"></div>

<script src="" data-host=""></script>

There's an example theme for how to style it in the git repo. I'll hopefully be adding a few more default themes to make it fit in other places better without extra work.

It's also possible to add other types of questions, such as ones that will only accept numeric input.

Or if you have specific data or want to make it easier for the user, there's even a multiple choice type.

It creates a fairly simple web interface to add surveys and manage responses. Future versions will contain more types of questions and potentially things like graphs of multiple choice responses.

I'd love to hear what you think about it or if you have any suggestions for new features! Of course, here's a simple form through it to answer this. It's also there to show off you don't need to include a description, only a title.

If you're curious about the name, I mostly use bird species to title my projects. Naming things is difficult!

LED Badges — PCB design

I've been attempting to design my own PCBs for the badges.

Using the same machine I engrave the acrylic with, I can engrave copper boards to create traces and drill holes. It seems to struggle with 10mil traces but the 20mil traces pictured below all look fully intact.

Now that I have boards that seem like they should work, I need to order the parts. My current part list includes:

  • ATTINY85-20SU — the main controller (might be possible to use an ATtiny45 for cost saving, there's enough RAM and storage if I don't add any sound reactive features)
  • MCP73831T-2ATI/OT — charging regulator for the lithium battery
  • 4.7µF 0805 capacitor — decoupling USB power in for charger
  • 4.99kΩ 0805 resistor — program charging regulator to 200mA
  • Micro USB female connector — provide power to the charging regulator
  • JST-PH 2 pin right angle connector — solderless battery connection
  • 350mAh 652030 lithium polymer battery — the battery to power it

I already have the pushbutton and toggle switches from previous projects.

I also need to get a SOIC socket so I can program the ATtinys as the boards don't have space for programming headers.

Component Count Price
ATtiny85-20SU 15 $16.93
MCP73831T-2ATI/OT 10 $5.21
652030 350mAh battery 2 $11.98
4.7µF capacitor 25 $1.24
4.99kΩ resistor 250 $1.60
Micro USB connector 10 $5.79
JST-PH 2-pin connector 10 $6.80
SOIC socket 1 $7.98

Total: $57.53 (before shipping and tax)

Board Layout

After getting the parts, I can evaluate how difficult everything is to hand solder. If I can't reliably make good connections, I'll have to look into hot air rework stations, solder paste, and solder masks. With those tools I could place everything and use the hot air to solder parts together instead of having to manually align and apply solder to each tiny pad. However, they can be expensive and difficult to get correct.

In addition to board design, some cheap electret microphone and amplifier boards I ordered arrived today. I'm using them to experiment with sound reactive features. I've started working with some example code to get a feel for how well they work. From the little time I've played with them, it feels more like a stretch goal rather than a core feature.

The components were purchased from Amazon, Arrow, and Adafruit. Most items are expected to arrive by Monday, May 21st. However, the JST connectors from Adafruit may take longer but they are not essential to prototyping.

Next up: waiting for the components to arrive and assembling a test board.

Engraved Acrylic LED Badges

Hi all, I'm writing this as an update for what I plan to happen regarding the LED badges.

Based on the experience Rynwar and I had with them at BLFC, there's a huge demand for something like these. In attempting to research what other people have done, I've run across a few other similar things but nothing quite as advanced in terms of color patterns and brightness. There are a number of people who print art onto acrylic or have laser engraved acrylic using art provided by the client. I have not found anyone else using RGB LEDs to create animated effects or ones that can be recharged instead of requiring replaceable batteries. From BLFC, they seem to last for about twelve hours on a single charge on the lower brightness mode. The final product likely would contain a larger battery for even longer battery life.

So far one artist has brought up the possibility of partnering to create artwork for the badges. I'd definitely like to pursue something like that instead of having to deal with the client providing artwork which may not be ideal for the engraving or they may not have permission to use.

Looking around has provided me with interesting ideas for dual layer acrylic which allows for multiple colors at once but I'm not sure how feasible this is with my current design. I believe it would be a very cool effect to get dual color artwork or a name that could flash independently of the artwork. In continuing to improve the features I'm also evaluating whether or not sound reactive patterns are possible (and it currently does seem likely I will be able to add reactive effects).

If you're not already familiar with what they look like, here's a few photos.

I'd love to get some feedback on what people would be comfortable spending on something like this. If you wouldn't mind filling out this quick question about it, I'd really appreciate it.

There's a number of issues with the current revision such as poor user interface (a single switch that controls mode and brightness), a large and clearly 3D printed case, and general imperfections in the acrylic (it was cut quickly on a table saw).

Moving forward, there's a number of refinements that must be reached before they could be sold. I have to figure out a new interface that allows enough configuration without being uncomfortable to use, how to cut and engrave the acrylic without imperfections, and generally improve the reliability and sturdiness of it. Hot gluing the acrylic in place worked well enough for a weekend but it does not feel sturdy. Even with being careful with them, the acrylic was covered in micro-scratches from the weekend. Although these scratches are not visible unless looking at the right angle, evaluating some kind of protective coating seems worthwhile.

The internals must also be significantly improved before I could manufacture them at any kind of reasonable rate. Currently, there are a number of hand soldered components pressure fit into place combined with off the shelf boards I already had. This means the space isn't used as efficiently as possible and the wires are potential points of stress and failure. I've been looking into a PCB design which will allow for more advanced features such as a microphone for sound reactive effects and better charging indicators. After finishing this design and sourcing the required components, I'll be able to get a better idea of how much each one of these costs to produce and therefore be able to determine how much they will be sold for.

Badge Internals

I'm hoping I'll be able to figure out all these issues within a few months. Once I have working prototypes for a more refined product, I'll open preorders but I cannot guarantee a date for this yet.


  • People seem to want these
  • I'm going to look into making them for people
  • There's a number of issues I need to figure out first
  • I don't know what they cost me yet or what I'm going to charge for them
  • I'm hoping to do preorders in a few months assuming everything works out

For future updates, check here.

Hello, world!

I have a blog now! Maybe I'll actually do some useful things with it.