Roll Your Own Rotary Encoders

[miroslavus] hasn’t had much luck with rotary encoders. The parts he has tested from the usual sources have all been problematic either mechanically or electrically, resulting in poor performance in his projects. Even attempts to deal with the deficiencies in software didn’t help, so he did what any red-blooded hacker would do — he built his own rotary encoder from microswitches and 3D-printed parts.

We know what you’re thinking: [miroslavus] hasn’t built a true encoder. There’s no attempt to encode the angular position of the shaft, nor is any information about the speed or direction of the shaft’s rotation captured. …read more http://pje.fyi/QGzC8P

Paul Jacob Evans

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Custom Parts Feeder Aims to Keep Pace with Pick and Place

When your widgets have proven so successful that building them gets to be a grind, it might be time to consider a little mechanical help in the form of a pick and place machine (PnP). If you’re going to roll your own though, there’s a lot to think about, not the least of which is how to feed your beast with parts.

Managing the appetite of a PnP is the idea behind this custom modular parts feeder, but the interesting part of [Hans Jørgen Grimstad]’s work-in-progress project has more to do with the design process. The feeders are to support …read more http://pje.fyi/QFlnK5

Paul Jacob Evans

Vintage Logan Lathe Gets 3D Printed Gears

In December 2016, [Bruno M.] was lucky enough to score a 70+ year old Logan 825 lathe for free from Craigslist. But as you might expect for a piece of machinery older than 95% of the people reading this page, it wasn’t in the best of condition. He’s made plenty of progress so far, and recently started tackling some broken gears in the machine’s transmission. There’s only one problem: the broken gears have a retail price of about $80 USD each. Ouch.

On his blog, [Bruno] documents his attempts at replacing these expensive gears with 3D printed versions, which so …read more http://pje.fyi/QB6PKy

Paul Jacob Evans

JST Is Not A Connector

When reading about cool projects and products, it’s common to see wiring plugs labelled “JST connector.” This looks fine until we start getting hands-on and begin hacking things together. Inevitably we find the JST connector from one part fails to fit in the JST connector of another. This is the moment we learn “JST” is not a connector specification. It is short for Japan Solderless Terminals Manufacturing Company, Ltd. A company whose history goes back to 1957 and their website (styled in 1999) lists hundreds of different types.

We can simplify to “JST connector” when chit-chatting about projects. But when …read more http://pje.fyi/Q7s92s

Paul Jacob Evans

A Sandbox for DIY Pinball Design

If you’ve always wanted to build your own pinball machine but have no idea where to start, this is the project for you. [Chris] is in the process of building a ¾ size pinball table and is currently in the waiting-for-parts stage. As they arrive, he is testing them in a sandbox he built in an afternoon. Let [Chris]’s proving ground be your quick-start guide to all the ways you could approach the two most important parts of any pin: the flippers and targets.

The field of play is a sturdy piece of particle board, and the cardboard walls are …read more http://pje.fyi/Q0RpLs

Paul Jacob Evans

Active Discussion About Passive Components

People talk about active and passive components like they are two distinct classes of electronic parts. When sourcing components on a BOM, you have the passives, which are the little things that are cheaper than a dime a dozen, and then the rest that make up the bulk of the cost. Diodes and transistors definitely fall into the cheap little things category, but aren’t necessarily passive components, so what IS the difference?

Resistors, Capacitors, Inductors, Transformers, Diodes*, and Memristors

That’s the list. Those are your passive components. Well, it’s not that easy. Also add in a bunch of types of …read more http://pje.fyi/Pw0DBw

Paul Jacob Evans

Radio Tuning The Quicksilver Way

Modern radios are often digital affairs, in which the frequency is derived from a stable crystal oscillator and varied through a microprocessor controlled frequency synthesiser. It won’t drift, and it’s exactly on the frequency dialed in. Older radios though relied on a tuned circuit, a combination of capacitor and inductor, for their frequency selection. If you were curious enough to peer inside — and we know you were — you’d have seen the moving vanes of a variable capacitor controlled by the tuning knob.

Of course, there is another way to adjust a tuned circuit: by changing the value of …read more http://pje.fyi/Pt7CZq

Paul Jacob Evans