The Robo Ruler Is a Combination Reference Tool and Adjustable 100-1.5k Ohm Resistor

Both a functional ruler and a programmable resistor, the Robo Ruler is a handy tool for a range of situations.

Gareth Halfacree
13 days agoHW101 / Debugging

Cyprus-based electronics design outfit Robo has built a PCB ruler with a difference: it's not just a reference tool, but a functional 100-Ohm-step decade box equivalent for figuring out the resistance you'll need in a circuit.

"When it comes to designing a product we always like to add at least a drop of innovation to it. Meet the Robo Ruler," the company writes of its latest design. "The Robo Ruler is made of the same material that most electronics boards are made of: FR-4. FR-4 is a composite material composed of woven fiberglass cloth with an epoxy resin binder that is flame resistant. Specifically, the Robo Ruler is made of FR4-Standard Tg 140C."

PCB rulers aren't anything new, of course, and the Robot Ruler ticks many of the boxes of its predecessors and rivals. There are metric centimeter markings to the face, with variable-height millimeter marks to make it easier to see where a measurement lies at a glance. The markings go complete to both edges, allowing the ruler to be used to measure from flat up against a starting point, and the rear of the ruler includes references for surface mount component and solder pad sizes, wire gauges from 26 to 10 AWG, and trace widths from 5 to 50 mil.

Unlike most of its rivals, though, there are components to the Robo Ruler — specifically, surface-mount resistors. Using pads on the ruler designed to be compatible with crocodile clips, these resistors can be connected up like a decade box — offering from 100Ω to 1.5kΩ in 100Ω increments. "The resistors have a double role," the board's creator adds, "not just to be used in electrical circuits but also to give a tight, firm grip when you hold the ruler down. That ruler won't slip out easily."

The Robo Ruler is now available on Robo's Tindie store at $9.99, in black or white finishes.

Gareth Halfacree
Freelance journalist, technical author, hacker, tinkerer, erstwhile sysadmin. For hire: freelance@halfacree.co.uk.
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