Month: September 2016

Books You Should Read: Poorly Made In China

September 9, 2016 by 110 Comments

This book is scary, and honestly I can’t decide if I should recommend it or not. It’s not a guide, it doesn’t offer solutions, and it’s full of so many cautionary tales and descriptions of tricks and scams that you will wonder how any business gets done in China at all. If you are looking for a reason not to manufacture in China, then this is the book for you.

The author is not involved in the electronics industry. Most of the book describes a single customer in the personal products field (soap, shampoo, lotions, creams, etc.). He does describe other industries, and says that in general most factories in any industry will try the same tricks, and confirms this with experiences from other similar people in his position as local intermediary for foreign importers.

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Very Simple PC Frequency Counter Works Up To 100MHz

September 9, 2016 by 32 Comments

We all use 74 logic in our projects as general purpose logic interfacing glue. These chips have become as ubiquitous as a general-purpose op-amp, or even as passive components. In most cases we’re not demanding much of them, and power requirements aside an original 74 chip from the dawn of the series could probably do the same job that we’re putting a more modern variant to work on.

It is easy therefore to forget that 74 logic is a field that has seen continuous improvement and innovation reflecting the developments elsewhere in electronics, and the most modern 74 versions hide some impressively high specifications.

A good example comes via a project from [Scott, AJ4VD], a very simple frequency counter that uses a single 74 series chip at its business end, and counts to over 100MHz. The chip in question is a 74LV8154 dual 16-bit counter which he is using as a prescaler to deliver a rate more acceptable to an ATMega328 microcontroller that does the counting. As he points out, the accuracy of a frequency counter is only as good as its gate timing, and he ensures as accurate a seconds-worth of pulses as he can with a 1PPS signal derived from an inexpensive GPS receiver. The 328 makes its counting available to a host computer via a serial port, and can be easily read through a terminal. He’s built it dead-bug style on a piece of unetched PCB, on which the simplicity of the circuit is evident.

There was a time when a project like this one would have required multiple integrated circuits including a probably quite expensive purpose-built prescaler. Cheap glue logic has now advanced to a stage at which it can be done instead at commodity prices, and we like that.

We’ve featured a few 74-series counters before, including this old-school one and this one also using a 74LV8154.

Life On Contract: Estimating Project Time

September 9, 2016 by 51 Comments

You sit there, irritation bubbling deep within as minute forty-five of the meeting ticks past on the clock in the corner of the office. Fight or flight is in a contest with your attention span as you struggle to keep an interested look on your face while they drone on. Real work could be done in this time. Maybe if you go to the bathroom you could sort of… fast forward the meeting. Panicked thinking continues for a bit until your awareness snaps back to the babble of words in the room.

“How long will it take you to do this?” the manager asks.

“A couple of days maybe?” You reply in turn. The manager nods and you take your escape. Little do you know that you have failed.

The project swerves out of control. Two days on the dot the manager is there expecting results. How? How did this happen again? It felt right! Two days is all you’d need to do such a simple project. It ended up taking a week.

The next meeting you say two weeks just to be sure. Everyone nods gravely, upset that something would take so long, but the work must be done. Two days later you sheepishly wander into the manager’s office with a completed project. He looks pleased but confused. The next meeting, he insists that you can do it in half the time. You and your fragile pride bowl ahead only to deliver late. The mystery!

This was my life until I started bugging the more experienced around me. I learned a lot from them and I ended up distilling it down into a few rules.

  1. There Is No Other Unit Than Hours
  2. Be honest.
  3. Get Granular.
  4. Promise a Range. Give a Deadline.

Why?

Why does someone want a time estimate? What are they going to do with this information? When working on a contract job it often feels like sticking a foot in a trap when a time estimate is given. Are they going to hold me to this? What if it goes wrong? After all, we are not fortune tellers. Unless the manager is extremely bad or you show yourself to be extremely lax in your duties, it is unlikely that a time estimate will be used against you.

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Raspberry Pi Radio Streaming Service Guts Yamaha Shelf System

September 9, 2016 by 9 Comments

There are dozens — dozens! — of options to meet your music and streaming needs these days.  Looking to make something of his own that retains that 90’s vibe of having a dedicated stereo system but with modern wireless integration, [thk4711] turned an old Yamaha hifi into a Raspberry Pi streaming client.

As far as the case goes, a few modifications allowed [thk4711] to use all of the existing buttons, and a quick-swap of the back-plate and screen gave him a better enclosure than one he could fabricate himself. The power supply proved to be the most difficult part of the project due in part to some “digital noise” interference between the digital and analog components while they were wired to a common ground. This was solved by implementing two transformers, a LM2596 voltage regulator and a LT1084 low-noise power supply to smooth things out.

The Raspberry Pi 2-centered device supports internet radio, Spotify connect, Airplay, USB and auxiliary inputs.

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Overhauling The ESP8266’s Flash Memory Handling

September 9, 2016 by 11 Comments

If you’ve ever corrupted a flash memory on a power failure, you’ll be glad to hear that the ESP8266 SDK implements a very secure and almost infallible read/write management for its flash memory. The catch: It’s also very wasteful. For a single memory block of stored data, three memory blocks of physical flash memory are occupied. [Peter Scargill] enlightens us with a better solution.

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Hackaday Prize Entry: Boots And Cats And Boots And Cats

September 8, 2016 by 13 Comments

Electronic drums are pricey, but the drums themselves are actually very easy to make. By simply putting a few piezos on some rubber mats, you can make a set of electronic drums. The real trick, and the expensive bit, is in the drum module. This module has inputs for the high hat, snare, toms, and bass drum to turn the repetitive thwaking of a stick on a rubber mat into drum sounds.

For his Hackaday Prize entry, [Jeremy] isn’t building a set of electronic drums. He’s building a drum module, complete with touchscreen interface and a GUI.

This isn’t [Jeremy]’s first go at building a drum module – his first implementation was RaspiDrums, an add-on for the Raspberry Pi that used accelerometers instead of piezos. The software works well enough with a USB sound card to serve as a set of real electronic snare.

Now [Jeremey] is moving up to a full kit, and the power of the Raspberry Pi means he can easily add a touch screen to his device. Right now the efforts are going into building a GUI using Gtkmm, and wrapping everything up into a front panel that makes sense and is easy to use. The drums themselves are a solved problem, making this Hackaday Prize entry a fantastic polish on an already great project.

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Cityscape Infinity Table

September 8, 2016 by 21 Comments

Redditor [ squishy0eye] lacked a coffee table and wanted an infinity mirror. So, in a keen combination of the two, she built an infinity mirror table the resembles a nighttime cityscape.

Skimming over many of table’s build details, [squishy0eye] paused to inform the reader that an MDF base was used underneath the mirrors, with a hole drilled for the future power cable. For the top pane, she overlaid privacy screen mirror film onto tempered glass, turning it into a one-way mirror. The bottom pane is acrylic plastic due to the need to drill holes to hide the cables for each ‘building’ — the same mirror film was applied here as well. Wood was cut into rectangles for the building shapes and super glued around the holes and in the corresponding spots underneath to prevent any bowing in the acrylic. A small gap was left in each ‘building’ to run the 5050 non-waterproof LED strips around and back into the hole for power.

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