Making a Larson Scanner

-using the SV2 Printer

BotFactory Inc., Afnan Islam

Introduction

Ever wanted to add a touch of retro-futuristic flair to your DIY projects with a mesmerizing light source? Building a Larson scanner using the innovative SV2 PCB printer might be just the thing. Not only is this project a nod to classic sci-fi aesthetics, but it’s also a fantastic way to explore modern PCB prototyping techniques.

What is a Larson Scanner?

A Larson scanner is a dynamic lighting effect where LEDs light up in a sequence, creating a back-and-forth motion that mimics the scanning eye of iconic robots like the Cylons from Battlestar Galactica or KITT from Knight Rider. Named after Glen A. Larson, the creator of these shows, this effect adds a captivating, animated touch to any project.

Designing the Circuit Board

Design time! We crafted our circuit using KiCad and exported the files in the trusty Gerber RS-274X format. At the heart of our board is an ATtiny chip, perfectly capable of driving a bunch of LEDs, resistors, and tactile switches. Powering it is as easy as plugging in a USB cable. For programming, we’ve thoughtfully included edge connectors—you can even use crocodile clips to access the SDA, SCL, RESET, VCC, and GND lines. How convenient is that? The board itself is a sleek two-layer design printed on FR4 substrate, inheriting all the classic properties you’d expect from this material.

But hey, let’s not get too deep into the design weeds. After all, the real star of the show here is the PCB prototyping process!

Setting Up the Software

After uploading your Gerber file (the system also supports image uploads), the SV2 printer initiates a series of verification procedures. It thoroughly analyzes multiple aspects of your design and performs an internal Design Rule Check (DRC) to ensure compliance with manufacturing standards.

The software interface offers extensive control over various print parameters. Users can adjust settings such as print height, select between substrate and substrateless printing modes, modify bed temperature, and fine-tune the UV curing process, among others. These customizable options enable precise optimization of the printing conditions to suit specific materials and design complexities.

Printing the PCB

With all settings configured, it’s time to proceed with the printing process. The SV2’s multi-material printhead employs piezoelectric technology to accurately deposit conductive inks and insulating layers. Printing this two-layer board typically takes around 35 minutes, depending on your specific configurations. After the print is complete, it is advisable to cut the board to its final dimensions before applying solder paste and initiating the curing process. The cutting method depends on whether you have printed on a substrate like FR4 or have opted for substrateless printing. We have developed new ink combinations that allow for the fabrication of exceptionally strong 3D-printed boards— you can learn more here.

If you are working with raw FR4 material, you can use a range of effective board-cutting tools suitable for different levels of complexity, from CNC routers to manual hand-cutters. For this particular project, manual board cutters are highly efficient, typically completing the task in just a minute or two. It’s important to note that we have deliberately excluded a CNC cutting head from our machine design because the dust produced from machining raw FR4 can be hazardous. Moreover, incorporating subtractive processes would contradict the principles of additive manufacturing that underpin 3D printing technology.

Applying Solder Paste

Transitioning from the printing stage, the next critical step is the application of solder paste. The SV2 printer is equipped with magnetic interchangeable heads, allowing for swift and effortless swapping between different functions. The solder paste dispensing head permits precise alignment of the dispensing nozzle, which can be adjusted in multiple ways to ensure optimal deposition. Ideally, this results in solder paste being accurately applied to all the pads on the PCB.

The image on the right demonstrates the paste alignment for the PCB design within the software UI. This adjustability ensures that even if the board has been manually cut—requiring some degree of manual intervention—the system can accommodate these changes. This flexibility maintains the precision necessary for effective solder paste application.

Pick and Place

The subsequent step involves the pick-and-place process for component assembly. The SV2 printer is equipped with another specialized interchangeable head that uses vacuum tips. This configuration enables precise and efficient picking of components from cut reels, which are placed on designated trays within the machine.

The system is capable of handling up to 53 components and can perform operations in batch mode for increased efficiency. Once calibration is completed, the printer’s head autonomously moves to accurately pick and place each component onto the PCB according to the design specifications.

Images on the left show component placement calibration displayed in the software user interface. In the second image, you can see the vacuum tip positioned over the onboard camera, rotating the component as necessary for accurate placement.

Curing

The bed used for substrate placement is actually a heatbed. This heatbed is instrumental in optimizing the surface energy of various substrates during printing, which enhances adhesion and print quality. Additionally, it makes reflowing solder paste much more efficient following the previous processes. Similar to other settings, the heatbed’s parameters are highly customizable, as shown below, and can be easily reverted to their original configurations by selecting the default profile.

Final Results

With all the steps completed, the final task is to upload your program to the ATtiny2313A microcontroller. Using the Arduino IDE simplifies this process significantly. Once you’ve uploaded the code, your Larson scanner is ready to showcase its mesmerizing LED sequence, bringing your project to life.

BotFactory’s New Mexico Experience

Pushing Boundaries with QStation

BotFactory Inc., Afnan Islam