WTF Are Ground Loops?

March 9, 2017 by Bob Baddeley 103 Comments

These magical creatures crop up out of nowhere and fry your electronics or annoy your ear holes. Understanding them will doubtless save you money and hassle. The ground loop in a nutshell is what happens when two separate devices (A and B) are connected to ground separately, and then also connected to each other through some kind of communication cable with a ground, creating a loop. This provides two separate paths to ground (B can go through its own connection to ground or it can go through the ground of the cable to A and then to A’s ground), and means that current may start flowing in unanticipated ways. This is particularly noticeable in analog AV setups, where the result is audio hum or visible bars in a picture, but is also sometimes the cause of unexplained equipment failures. Continue reading “WTF Are Ground Loops?” →

Don’t Fear The Filter: Lowpass Edition

March 8, 2017 by Elliot Williams 31 Comments

There comes a time in every electronic designer’s life when, whether they know it or not, they need an analog filter in their design. If you’re coming from a digital background, where everything is nice and numeric, the harsh reality of continuous voltages can be a bit of a shock. But if you’re taking input from, or sending output to the big analog world out there, it pays to at least think about the frequency-domain properties of the signal, and maybe even do something about them.

Designing an analog filter to fit your needs can be a bit of a daunting task: there are many factors that you’re going to need to consider, and they all interact. It’s easy to get lost. We’re going to simplify this as much as possible by instead focusing on a few common applications and building up the simplest possible filters that work well for them.

Today, we’re going to consider the lowpass filter, and specifically a Sallen-Key filter with Butterworth characteristics and a second-order rolloff. Sound like word salad? We’ll fix that up right away, because this is probably the single most important filter to have in your analog toolbox for two very common use cases: pulse-width modulated (PWM) output and analog-to-digital conversion (ADC) input.

Continue reading “Don’t Fear The Filter: Lowpass Edition” →

Friday Hack Chat: Mechanical Manufacturing

March 8, 2017 by Mike Szczys 3 Comments

Join [Sylvia Wu], a Senior Manufacturing Engineer at Fictiv, for this week’s Hack Chat. [Sylvia’s] work at Fictiv gives her a unique viewpoint for modern manufacturing. The company connects engineers with rapid manufacturing by taking in a design and routing it to a shop that has the tools and time to fabricate the part quickly. This means seeing the same silly mistakes over and over again, but also catching the coolest new tricks as they pass by. She also spends time tearing apart consumer products to see how they have been manufactured, adding to their arsenal of available processes, both time-tested and newfangled.

Anyone interested manufacturing needs to get in on this Hack Chat. Mark your calendar for this Friday, 3/10 at noon PST (20:00 UTC)

Here’s How To Take Part:

Our Hack Chats are live community events on the Hackaday.io Hack Chat group messaging.

Log into Hackaday.io, visit that page, and look for the ‘Join this Project’ Button. Once you’re part of the project, the button will change to ‘Team Messaging’, which takes you directly to the Hack Chat.

You don’t have to wait until Friday; join whenever you want and you can see what the community is talking about.

Upcoming Hack Chats

On Friday March 17th the Hack Chat features chip design for oscilloscopes with engineers from Keysight.

Saved By The Bel — Understanding Decibels

March 7, 2017 by Al Williams 20 Comments

If you’ve hung around electronics for any length of time, you’ve surely heard of the decibel (often abbreviated dB). The decibel is a measure of a power ratio. Actually, the real measure is a bel, but you almost never see that in practice. If you are versed in metric, you won’t be surprised to learn a decibel is 1/10 of a bel. Sometimes in electronics, we deal with really large ratios, so the decibel is logarithmic to cope with this. Doubling the number of decibels doesn’t double the ratio, as you will soon see. It’s all about logarithms, and this ends up being extremely useful when measuring something like antenna or amplifier gain.

Besides antennas, decibels are often used to measure sound and light. The reason is that human ears and eyes have a logarithmic response to those quantities. Your ear, for example, has a huge dynamic range. That is to say, you can hear a whisper or a space shuttle launch. That ratio is about 1 trillion to 1, but that’s only 120 dB. This is also why potentiometers made for volume controls have a logarithmic taper. A linear pot would seem off because, for example, a tenth of a turn at one extreme will affect the apparent volume much more than a tenth of a turn at the other extreme. This holds true whether or not those knobs go up to eleven.

Continue reading “Saved By The Bel — Understanding Decibels” →

Los Angeles Hackaday Unconference Happening On 3/18

March 6, 2017 by Mike Szczys 3 Comments

Reserve your spot at the Los Angeles Hackaday Unconference on Saturday, March 18th. The Hackaday community is huge in LA and this event will fill up, so don’t delay.

The Unconference is a unique opportunity to decide the course of the day as it happens. Everyone who attends should be ready to stand and deliver at least eight minutes on a topic they find exciting right now. The energy this creates is the key to a level of involvement that can’t be matched at traditional conferences that have a divide between those presenting and those attending.

LA Joins Chicago and San Francisco

This announcement of the Los Angeles Hackaday Unconference joins two others happening the same day. Last week we announced San Francisco as a host location and the event is now full… but anyone in the area should still get their name on the waiting list. Four days ago we announced Chicago as the second location and that event will likely reach capacity today. [Shulie Tornel] and [Jasmine Brackett] are organizing things at the LA event which is being held at the Supplyframe Design Lab from 1 – 8 pm on 3/18.

Build Something that Matters

You can speak on any topic you want, but sometimes having a theme helps to get the ideas flowing. When considering your topic, keep Build Something that Matters in mind. Have you been looking into a technology, project, or idea that can make life a little (or a lot) better for the world? That would be an exquisite topic.

At the beginning of the day we’ll go around the room and get the talk title or subject from everyone there, then as a group we’ll hammer out a schedule for the day. As presentations progress, we encourage new impromptu talks to spring up, and can even split those off into a second talk space or discussion group. We’ll have food and drink on hand, as well as some interesting hardware to give out as door prizes.

The Hackaday Unconference is the ultimate idea and energy exchange in a crowd of your peers. You’ll have a hard time finding a cooler way to spend a Saturday this year. See you there!

Ask Hackaday: How Should Hackers Handle IP Agreements?

March 6, 2017 by Dan Maloney 82 Comments

My buddy Harold recently landed a new job at a great technology company. It came at a perfect time for him, having just been laid off from the corporate behemoth where he’d toiled away as an anonymous cog for 19 years. But the day before he was to start, the new company’s HR folks sent him some last-minute documents to sign. One was a broad and vaguely worded non-compete agreement which essentially said he was barred from working in any related industry for a year after leaving the company.

Harold was tempted not to sign, but eventually relented because one needs to put food on the table. Thankfully he’s now thriving at the new company, but his experience got me thinking about all the complications hackers face with the day jobs that so many of us need to maintain. Non-competes and non-disclosures are bad enough, but there’s one agreement that can really foul things up for a hacker: the Intellectual Property Agreement.

Continue reading “Ask Hackaday: How Should Hackers Handle IP Agreements?” →

Record Players Explained For The Streaming Generation

March 3, 2017 by Jenny List 68 Comments

How do you consume your music, these days? Aside from on the radio, that is. Do you play MP3 or other files on your phone and computer, or perhaps do you stream from an online service? If you’re really at the cutting edge though you’ll do none of those things, because you’ll be playing it on vinyl.

The legendary Technics SL1200 direct-drive turntable, as used by countless DJs. Dydric [CC BY-SA 2.5)], via Wikimedia Commons. — The legendary Technics SL1200 direct-drive turntable, as used by countless DJs. Photo by Dydric CC-BY-SA 2.5

A few years ago reporting on a resurgence of sales of vinyl records was something you would never have expected to see, but consumer tastes are unpredictable. Our red-trousered and extravagantly bearded hipster friends have rediscovered the glories of the format, and as a result it’s popping up everywhere. For those of us who are old enough to have genuinely been into the format before it was cool again, the sight of Sergeant Pepper and Led Zeppelin II on 12″ at outrageous prices on a stand at the local supermarket is a source of amusement. It’s good to see your first love back in vogue again, but is it really the £20($25) per album kind of good?

With the turntable having disappeared as an integral part of the typical hi-fi setup the new vinyl enthusiast is faced with a poor choice of equipment. Often the best available without spending serious money at an audiophile store is a USB device with the cheapest possible manufacture, from which the playback will be mediocre at best. We’ve lost the body of collective knowledge about what makes a good turntable to almost thirty years of CDs and MP3s, so perhaps it’s time for a quick primer.

Continue reading “Record Players Explained For The Streaming Generation” →