Monthly Archives: May 2018

Free PCB Sunday: Pick your PCB

via Dangerous Prototypes


We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service. This week two random commenters will get a coupon code for the free PCB drawer tomorrow morning. Pick your own PCB. You get unlimited free PCBs now – finish one and we’ll send you another! Don’t forget there’s free PCBs three times every week:

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Be sure to use a real e-mail in the address field so we can contact you with the coupon.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.
  • PCBs are scrap and have no value, due to limited supply it is not possible to replace a board lost in the post

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App note: How to properly configure unused operational amplifiers

via Dangerous Prototypes


Good read app note from Texas Instruments about configuring unused op amps on multi amp chips. Link here (PDF)

Multi-channel operational amplifiers (op amps) are often implemented in circuits that do not require the use of all channels. Undesired behavior in an unused amplifier channel can negatively impact system performance, as well as the performance of the channels in use. To avoid degradation of both the op amp and system performance, the unused op amp channels must be configured properly.

App note: Current sense amplifiers in class-D audio subsystems

via Dangerous Prototypes


App note from Texas Instruments about output current sensing in class-D amplfiers. Link here (PDF)

Current sensing in audio subsystems are widely used in conjunction with CLASS-D amplifiers for diagnostics or to provide speaker current feedback to the DSP for speaker enhancement to emulate smartamp. The most expensive component in the audio subsystem is the speaker. The impedance of the speakers ranges from 2Ω for subwoofer to a 8Ω for stereo speakers. Exceeding the current flowing through the speakers has a potential to create excessive heat in the voice coil which can lead to permanent damage of the speakers.

Save on all active Pololu-brand products, now through Tuesday

via Pololu Blog

Over the next few days, we’re welcoming summer by discounting all active Pololu-brand products, which is almost everything we make. If you’re about to have a lot of free time on your hands, why not spend some of it building a robot? And if you’re going to be as busy as ever this summer, why not unwind by building a robot?

Check out the sale page for details!

Please note that we will be closed on Monday for Memorial Day, so orders will not ship until Tuesday, May 29.

Friday Product Post: Get the Lowdown on LoPy

via SparkFun: Commerce Blog

Hello everyone and welcome to another fantastic Friday Product Post. We have a set of some great LoRa IoT products from Pyco: the LoPy4, Pycom Expansion Board and LoRa/Sigfox Antenna Kit are all available starting today and we couldn’t be happier! On top of these three new products we also have a large Jumper Wire Kit with 700 wires ready for you to start prototyping with right away. Let’s jump in and take a closer look!

Hey, buddy! HIGH PY-VE!

Pycom LoPy4 Development Board


The LoPy4 is a compact, quadruple network, MicroPython-enabled development board (LoRa/Sigfox/WiFi/Bluetooth). It’s the perfect enterprise-grade IoT platform for your connected projects. With the latest Espressif ESP32 chipset, the LoPy4 offers a perfect combination of power, friendliness and flexibility. Create and connect your things everywhere – fast.

Pycom Expansion Board 3.0


Your Pycom module will need a way to be programmed; that’s where this board comes in! The Pycom Expansion Board 3.0 allows you to create and connect new IoT projects with your WiPy 2.0, WiPy 3.0, LoPy, LoPy4, SiPy, FiPy and GPy! With dozens of ready-to-use templates and libraries, developing a new IoT solution is now easier and faster.

Pycom LoRa and Sigfox Antenna Kit


If you use the LoRa or Sigfox connectivity on the LoPy4, you will need to connect a special antenna beforehand, otherwise you risk damaging the device. Luckily, with this Antenna Kit from Pycom, you won’t need to worry about hurting your fancy LoPy4. This universal LoRa and Sigfox Antenna Kit can also be used with LoPy, SiPy and FiPy IoT development boards.

Large Jumper Wire Kit - 700pcs


You ask for more wires, you get more wires. This is a large kit of jumper wires all cut, stripped and pre-bent for your prototyping pleasure. Included with this kit are 14 various lengths of 22AWG wire - 2, 5, 7, 10, 12, 15, 17, 20, 22, 25, 50, 75, 100 and 125mm - 50 pieces of each.

If you are looking for something a little smaller, we still have a jumper wire kit with 140pcs available as well.

And that’s it everyone! We are very excited to finally have the LoPy4 available and can’t wait to see what you make with it! Shoot us a tweet @sparkfun, or let us know on Instagram or Facebook. We’d love to see what projects you’ve made!

We’ll be back next week with even more fantastic new products!

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Inside the 76477 space invaders sound effect chip: Digital logic implemented with I2L

via Dangerous Prototypes


Ken Shirriff has written an excellent in-depth look at the 76477 sound effects chip:

The 76477 Complex Sound Generation chip (1978) provided sound effects for Space Invaders1 and many other video games. It was also a popular hobbyist chip, easy to experiment with and available at Radio Shack. I reverse-engineered the chip from die photos and found some interesting digital circuitry inside. Perhaps the most interesting is a shift register based white noise generator, useful for drums, gunshots, explosions and other similar sound effects. The chip also uses a digital mixer to combine the chip’s different sound generators. An unusual feature of the chip is that it uses Integrated Injection Logic (I2L), a type of digital logic developed in the 1970s with the goal of high-density, high-speed chips. (I wrote about the chip’s analog circuitry last year in this article.)

See the full post on his blog here.