An Arduino version of Brooks Shera’s GPSDO

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Jeff (aka K6JCA) has a great write-up on implementing the Brooks Shera Phase-Locked Loop GPSDO on an Arduino Platform:

This blog post is a continuation of my two earlier GPSDO blog posts. The first one (from a few years back) details a simple Frequency-Locked Loop GPSDO design, based around an Arduino processor. The second (more recent) blog post discusses simulating Brooks Shera’s GPSDO algorithm (from the July, 1998 issue of QST) using The MathWorks Simulink program.
This third blog posts describes my modification of my original Frequency-Locked Loop (FLL) GPSDO to be a Phase-Locked Loop (PLL) GPSDO, and it includes the hardware schematics, Simulink models, and the Arduino code I wrote to implement Brooks Shera’s GSPDO algorithm on an Arduino processor.

More details on K6JCA blog.

from Dangerous Prototypes http://bit.ly/2GmnZXF

App note: MELF resistors – The world’s most reliable and predictable, high-performing film resistors

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App note from Vishay on why MELF resistors are so successful and has no alternative in today’s application. Link here (PDF)

For more than 25 years, Vishay’s MELF resistors have successfully met the demanding requirements of the automotive industry. They offer superior SMD resistor performance in terms of accuracy, stability, reliability, and pulse load capability. The cylindrical construction of MELF devices provides an optimal power rating and pulse load capability related to the mounting space. Continuous development has led to improved long-term stability and moisture resistance, and allows high-temperature operation to + 175 °C.

from Dangerous Prototypes http://bit.ly/2DpT21a

Serial Star, a 4 in 1 USB serial and I2C converter

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Jesus Echavarria published a new build:

Here’s one of the last board I design the last year. On 2016, I develop the Dual USB Serial and I2C Converter board. Although this board works fine, it has a couple of lacks. First one, is that to use the both converters, you need two free USB ports. Is a minor problem today with USB hubs, but you need the hub and also two USB wires. And the other problem is that this board uses mini-USB connectors. Of course today you can still find it, but aren’t as common as the micro-USB wires. For this two reasons, I decide to upgrade the board, add the micro – USB connector and put a USB hub inside it. Because I choose a 4-port USB hub, I use also 4 USB serial converters. With some addons, you can select power supply value (5V, 3V3), serial levels (TTL, RS232) and GPIO functions in an independent way for each converter. So, let’s see how works this USB Serial Star, a 4 in 1 USB to Serial and I2C Converter.

More details on Designing Electronics in Spain blog.

from Dangerous Prototypes http://bit.ly/2DY54A3

Teardown of a Piezoelectric vibrating gyroscope

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Kerry Wong did a teardown of an old analog piezoelectric vibrating gyroscope:

Gyroscopes nowadays are based on micro-electro-mechanical systems (MEMS) technology. They are low cost and extremely miniaturized. A device combing both a three-axis gyroscope and a three-axis accelerometers (sometimes these devices are referred to as 6DOF devices) such as the MPU-6500 for example can be had in a QFN package as small as 3 mm x 3 mm and under 1 mm in height. Before these MEMS devices gained mainstream popularity however, larger piezoelectric vibrating gyroscopes were used in many consumer electronics devices.

See the full post on his blog.

Check out the video after the break.

from Dangerous Prototypes http://bit.ly/2DUP3ev

#FreePCB via Twitter to 2 random RTs

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Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters. Don’t forget there’s free PCBs three times a every week:

  • Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch it every Sunday, right here on the blog
  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs will be your friend for the weekend

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Check out how we mail PCBs worldwide video.
  • We’ll contact you via Twitter with a coupon code for the PCB drawer.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.

from Dangerous Prototypes http://bit.ly/2WRNgOK

Solar powered weather station

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Antalife has written an article detailing the build of his a solar powered weather station:

To expand my microcontroller and programming knowledge I have decided to try and make a Solar Powered Weather Station. My goal is to record parameters like:
*Temperature
*Humidity
*Air pressure
*Air quality (something to do with CO or CO2)
I then hope to send (wirelessly) the data to a base station and log/display it on a simple website. To make things interesting I also aim to power the data gathering station from a large supercapacitor (~100F), and in keeping with my solar tradition the supercapacitor will be charged from a solar-cell.

See the full post on his blog.

from Dangerous Prototypes http://bit.ly/2DUfh0A

Free PCB Sunday: Pick your PCB

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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

Be the first to comment, subscribe to the RSS feed.

from Dangerous Prototypes http://bit.ly/2BiIoJf

App note: Understanding the characteristics of Li-ion batteries and Richtek power management solutions

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App note from Richtek on how to work with Li-ion batteries properly. Link here

Lithium-ion/polymer rechargeable batteries, which have been widely used today, have distinguished properties, but are very delicate and have to be used with extreme care. Improper use of Li-ion batteries will bring about catastrophic consequences. The incidences of burning and explosions of Li-ion batteries have often been heard. Carefully understanding their properties and adopting a right battery management method is most essential for making good use of Li-ion batteries.

from Dangerous Prototypes http://bit.ly/2HNpSy8