July 28, 2016 0 Comments AUTHOR: Donald Bell CATEGORIES: Kits, News, Project Tags: , , , , , , , , , , , , , ,

Tap Sensor Kit Blends Vintage Circuit With Fresh Design

Tap Sensor PCB with backlight
The Tap Sensor from Boldport. Photo by Donald Bell.

Boldport’s Tap Sensor project is a beautiful refresh of a project that first appeared in the premier issue of 1974’s Elektor magazine. The organic lines of the circuit board traces — a hallmark of Boldport’s design aesthetic — look right at home on this retro project, which is largely unchanged from the original ‘70s design.

The kit includes the bare board, a few stickers, a printed link to project information, and all of the electronic components you’ll need to complete the board. In order to functionally demonstrate the project you will also need three LEDs, a breadboard, some hookup wire, female-male header wires, and a 5v power supply. If you’ve completed Boldport’s Cordwood Puzzle project, you can also hook the Tap Sensor directly to it with some header wires and skip the breadboard and LEDs.

Boldport Tap Sensor Kit Contents
The Boldport Tap Sensor Kit comes with the beautiful custom PCB and all of the components you’ll need to complete the project. Photo courtesy of Boldport.

Because Boldport’s boards are so thoughtfully labeled on the underside with component outlines and reference numbers, the project basically revolves around correctly placing and soldering things, with bonus points for clean, tight work that can complement the beauty of the board.

Boldport Tap Sensor PCB detail
The bottom of the Tap Sensor PCB includes outlines and reference numbers for each of the components. You’ll have to reference the schematic, however, to figure out exactly what goes where. Photo courtesy of Boldport.

I’m tempted to call it a beginner project, if not for the fact that there’s no step-by-step guide, and you’ll have to do some dancing back and forth between the schematic to understand what component values go where. If (like me) reading resistor values aren’t second nature to you, you’ll need to look those up and label each reel. The same goes for the capacitor values. Personally, I appreciate the challenge at this point, but I would have found it frustrating a few years back when I was still struggling to wrap my head around electronics.

Completed Boldport Tap Sensor Board
Here you can see the completed. Tap Sensor board. To make it do something, you’ll need to connect it up to 5v power and wire the outputs (across the top) to something that will react to 5 volts. I went with LEDs (see below) to test the circuit, but connecting this up to an Arduino opens many more possibilities. Photo by Donald Bell.

For better or worse, the finished board doesn’t include a built-in payoff. That is, the board itself doesn’t include blinking LEDs or sonic beeps of victory to signal that you’ve connected everything properly. Instead, it’s on you to wire the Tap Sensor to both power and something for it to control. The easiest and fastest way to accomplish this is to have it control three LEDs set into a breadboard.

Boldport makes it obvious where to wire 5v and ground to the Tap Sensor board. Whether by design or oversight, it’s less clear where the outputs are. Through some trial and error I was able to get my LEDs to light up by exploring the headers at the top of the board. To understand what was actually happening, though, I had to jump down the rabbit hole of the original 1974 circuit documentation. Here’s where the real education comes in. Curious minds can learn all about how the circuit harnesses the logic gate functionality of the two TI SN7400 ICs to switch and route power across the board.

Tap Sensor Breadboard Wiring

Boldport Tap Sensor on Breadboard
Testing the Tap Sensor board using just 3 LEDs and a few hookup wires.

This is where I get out of my depth, but I think it’s great that there’s so much substance to dive into for curious or advanced makers. For more casual tinkerers like myself, it’s enough to know that the board’s top header pins act as the 5v outputs, expressed as three interdependent switches. The more you explore and play with these three sections (each made up of four pins), you can get a sense for how the logic gates trigger and cascade over from one another across the board.

Tap Sensor Schematic

The Bottom Line

The Tap Sensor kit from Boldport is a quick build that looks great and integrates well into other projects that are able to make use of its 5v output as either a trigger (Arduino) or a power source (LEDs). Because the instructions are a bit hands-off and the end result requires some additional wiring for a payoff, it’s a project better suited for those with some electronics experience already under their belt. That said, if it’s a project you’d really like to take on, the Slack support group for Boldport is friendly and helpful and includes great advice for each project.


Time to complete: 30 minutes
Type: Electronic
Best for: Makers with some electronic experience, comfortable with soldering, able to understand the basics of a simple schematic or challenge themselves to learn.
Cost: $17 ($65 Club Membership required, includes 3 additional projects, shipped monthly)
Payoff: A credit card-sized touch-sensitive board that can switch 5v between 3 independent outputs. Requires external power source and needs something to switch (LEDs, Arduino project, relays).
Skills learned: Soldering, component identification, schematic reading, breadboarding, logic gates.
Tools needed: Soldering iron, solder, flush cutters, 5v power supply, breadboard, LEDs, hookup wire, female-male header wires.

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