This PCB Reference Ruler Is Ideal for the Raspberry Pi Enthusiast
Having failed to find a PCB reference ruler that ticked all the boxes, Ian Dunn created his own — with an eye on the Raspberry Pi.
Raspberry Pi enthusiast Ian Dunn is the latest to enter the world of PCB reference rulers, launching a crowdfunding campaign for a pocketable guide to both general electronics and the Raspberry Pi's general-purpose input/output (GPIO) port.
"The moment I learned about PCB rulers I had to have one. But no PCB ruler that I could find on the internet was quite what I wanted, so I made my own," Dunn notes. "I put quite a bit of time and effort into perfecting this ruler, and I think the end product is really nifty. So, it seemed like a shame not to share it.
"I crammed every piece of information about the Raspberry PI and electronics that I could onto the ruler. My goal was to put every pinout and formula that I use from time to time but I don't quite remember in one easy place. It's exactly the right size to fit into a shirt pocket, and it's very attractive. The finish is lead free ENIG (Electroless Nickel Immersion Gold.) The circuit board material is FR-4 with green solder mask."
The 15cm/6" ruler includes 1mm and 1/16" markings for general measurement, the 40-pin Raspberry Pi GPIO header pinout, gauges for wire diameters from 10 to 28AWG, trace widths from 10mils to 80mils and .25mm to 2mm, and Ohm's Law on the front. The rear includes a guide to reading resistor color codes and pin-outs and package markings for an LED, bipolar junction transistor, field-effect transistor, USB 2.0 plugs, and RJ45 T-568B, along with references for font heights from .75mm to 4mm and formulae for resonant frequency plus capacitive and inductive reactance.
"These rulers are rather expensive to manufacture in small batches, so I need your help," Dunn explains of his crowdfunding campaign. "At minimum, I can sell the prototype batch that I already have manufactured, but I would really like to manufacture 1000 or more rulers."
The campaign has already blown past Dunn's modest $200 funding goal, with a few weeks left on the clock. The rulers are available to order priced at $8 from the Kickstarter campaign page, with delivery expected in April 2020.