App note: MOSFET power losses and how they affect power-supply efficiency

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Here’s an application note (PDF!) from Texas Instruments on MOSFET power losses and how they affect power-supply efficiency:

Power-supply efficiency is a critical criterion for today’s cloud-infrastructure hardware. The efficiency of the chosen power solutions relates to system power loss and the thermal performance of integrated circuits (ICs), printed circuit boards (PCBs), and other components,which determines the power-usage effectiveness of a data center.
This article revisits some of the basic principles of power supplies and then addresses how MOSFETs—the power stage of any switching-voltage regulator—affect efficiency.

USBuddy: USB development tool

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Jakub has designed and built a USB breakout board with current monitor, an open hardware tool – USBuddy:

Do you sometimes develop with USB? I do. So I need to access data lines, bus voltage and I’d like to easily monitor the current too. I made myself a small companion (43.5 mm × 22.5 mm, 9.5 g) to do that. Just a simple breakout board with one connector in and one out. And a little extra to make things easier. I call it USBuddy.

Project info at Kaktus Circuits blog. It’s also up on Tindie.

Free PCB coupon via Facebook to 2 random commenters

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Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. The coupon code usually go to Facebook ‘Other’ Messages Folder . More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three times every week:

Continue reading “Free PCB coupon via Facebook to 2 random commenters”

Getting started with OPENOCD using FT2232H adapter for SWD debugging

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Yahya Tawil wrote a tutorial about flashing EFM32 MCUs with OpenOCD using FT2232H adapter:

Learn how to make flashing your ARM-based MCU easy by using OpenOCD debugger with an FT2232H adapter.
Old MCUs from vendors like ATMEL and MICROCHIP, like the PIC16F and Atmega family, tend to have a special programming interface to program internal flash. For example, Atmega used SPI pins (MISO, MOSI, SCK) and PIC used two pins (PGC, PGD)— one as a clock and another as a bi-directional data line.
New MCUs, especially with an ARM core, use JTAG/SWD as a programming/debugging interface.

Full details at All About Circuits homepage.

Crystal motional parameters

Craig writes:

Ever tried searching through your datasheets for the motional parameters of that quartz crystal you just bought? Good luck! Vendors simply don’t specify these parameters to general end users, and for most applications that’s OK. But for high Q oscillator and filter design, measuring and matching crystals can be important.
This video discusses crystal motional parameters, how to measure them with a crystal impedance meter, and finally examines the measured values of 150+ real world crystals.

More details at Analog Zoo.

More Energy monitoring – ATM90E26 Breakout

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A Breakout board for the ATMEL E9026 Energy monitor from Whatnicklife:

What is it?

ATM90E26 breakout for AC energy monitoring. It allows development of code and applications conveniently.

Why did you make it?
I wanted to test various energy monitor ASIC’s. I have already made an ADE7763 Breakout, I wanted to try the ATM90E26 for comparison and ease of use (SPI/UART alternatives). However it is not cheap since ATMEL’s version of the EVM is too expensive, aimed at the enterprise rather than electronics hobbyists.

So I took the low voltage parts of the reference design and made a breadboard friendly breakout.

Project info at Tisham Dhar’s blog.  It’s also up on Tindie.

Arduino RFID login

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Luke has published a new build:

I wanted a simple way of quickly logging on to my computer without having to typing my password in and did not want to have no security either.
There are various products on the market that would solve this problem from fingerprint readers to proximity dongles but i decided to see what i could knock up with parts i mainly already had.

Looking in my micro stuff i had a RC522 RFID tag reader 3.3v :
Also an 3.3v arduino Leonardo clone aswell based on a sparkfun pro micro which also can act as a USB device such as a keyboard. This is useful as if a 5v arduino was used a level shifter would be required due to the RC522 not being 5v torrent.

More info at Luke’s project page.

Analysis, operation, and modification of a switchmode power supply (SMPS) for variable output voltage

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Lindsay Wilson did a teardown/modification of a Chinese SMPS to allow an adjustable output voltage:

I’m currently working on a product which uses a size 2430 “hobby” brushless motor and 25A electronic speed controller (ESC). In its “intended” use, the controller runs from two lithium-ion batteries with a total voltage of around 7.4V, but I want to run it from a mains-derived power supply instead. However, there are no off-the-shelf supplies available with that output voltage.
Fortunately, there is no shortage of inexpensive Chinese switchmode supplies with standard outputs of 5,12,24V etc. Most (all?) of these have the ability to adjust the output voltage slightly, by around ±10%. I reckoned that it should be possible to modify such a supply to provide a fully-adjustable output voltage which could be set to the desired 7.4V. This is by no means a novel idea – many people have modified supplies (a common mod is to increase the output to 13.8V, for ham radio use) – but I haven’t seen a good operational analysis of these supplies, so it’s a good excuse to do some detective work and figure out what makes them tick.

Full details at Imajeenyus homepage.

Check out the video after the break. Continue reading “Analysis, operation, and modification of a switchmode power supply (SMPS) for variable output voltage”

#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.

Butchered USB TTL serial adaptor

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Turning a USB to RS232 adaptor into a USB to TTL serial adaptor by Aaron Brady:

I didn’t want to wait, so I had a look around what we had on hand. We did have a spare RS232 to USB adaptor. This one speaks the full ±15V, and I briefly considered using one of the spare MILSPEC SP232’s we got cheap to bring it down to TTL, but that seemed mad: there was going to be a MAX232 or similar in the serial adaptor bringing it up to voltage so it could go a couple of centimetres before getting stepped down again.
Here begins our adventure into very small wires, fine SMT soldering and hot glue.
We popped open the case, and there were two main ICs, a Prolific 2303 (the USB to Serial IC) and a ADM3251E (the RS232 line level convertor). I tried to desolder this with no success, but Bas stepped in, cut the leads with a craft knife and ran the iron over the chip’s leads and it basically fell off. He also did the very fine soldering to pins 1 and 5 of the Prolific chip, TX and RX respectively.

Project info at Aaron’s blog.

Eagle CAD tips and tricks, part 2

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Here’s the part 2 of Yahya Tawil’s Eagle CAD tips and tricks we covered previously:

In part 1, we talked about the importance of issuing commands with your keyboard and using your mouse effectively. In this part, we will continue talking about other useful tips and tricks for using Eagle CAD.
Read part 1’s tips and tricks here.

More details at All About Circuits homepage.

Via the contact form.

Quick PCB: TCXO Breakout

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Dan Watson has published a new build:

There are some good, inexpensive TCXO modules on eBay that come in the slightly unusual package shown above. This breakout board allows you to mount one of the modules onto the small PCB and adapt it to standard 0.1″ breadboard-compatible headers. I have also included a few optional SMD components. There are spots for a power LED, a bypass capacitor on the supply rail, and a capacitor on the control voltage input.
Some of these modules don’t actually have a control voltage input on pin #1. Typically they have a small trimmer on top for adjusting the frequency, which is probably more useful for how these are commonly used. If you have access to a disciplined frequency reference such as a GPSDO, you should allow the module to warm up for 24 hours and then trim the frequency.

More details at The Sync Channel blog.  Project files available at Github.

App note: CCD Fundamentals

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ON Semiconductor’s Charge-Coupled Devices primer application note. Link here (PDF)

Like many technologies, the Charge-Coupled Device (CCD) started out as one kind of creature and wound up as something completely different. Invented in the late 1960’s by researchers at Bell Labs, it was initially conceived as a new type of computer memory circuit, and it was demonstrated in 1970 for that facility. It soon became apparent that the CCD had many other potential applications, including signal processing and imaging, the latter because of silicon’s light sensitivity that responds to wavelengths less than 1.1 m (the visible spectrum falls between 0.4 m and 0.7 m). The CCD’s early promise as a memory element has since disappeared, but its superb ability to detect light has turned the CCD into the premier image sensor technology.

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:

Continue reading “Free PCB Sunday: Pick your PCB”

App note: Understanding data eye diagram methodology for analyzing high speed digital signals

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Application note from ON Semiconductors about the Data eye diagram methodology to represent and analyze a high speed digital signal. Link here (PDF)

The eye diagram allows key parameters of the electrical quality of the signal to be quickly visualized and determined. The data eye diagram is constructed from a digital waveform by folding the parts of the waveform corresponding to each individual bit into a single graph with signal amplitude on the vertical axis and time on horizontal axis. By repeating this construction over many samples of the waveform, the resultant graph will represent the average statistics of the signal and will resemble an eye. The eye opening corresponds to one bit period and is typically called the Unit Interval (UI) width of the eye diagram. An ideal digital waveform with sharp rise and fall times and constant amplitude will have an eye diagram.

App note: STM32 cross-series timer overview

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STM32 timer overview application note (PDF!) from ST:

The STM32 devices are built-in with various types of timers, with the following features for
each:

  • General-purpose timers are used in any application for output compare (timing and delay generation), one-pulse mode, input capture (for external signal frequency measurement), sensor interface (encoder, hall sensor)…
  • Advanced timers: these timers have the most features. In addition to general purpose
    functions, they include several features related to motor control and digital power
    conversion applications: three complementary signals with deadtime insertion,
    emergency shut-down input.
  • One or two channel timers: used as general-purpose timers with a limited number of
    channels.
  • One or two channel timers with complementary output: same as previous type, but
    having a deadtime generator on one channel. This allows having complementary
    signals with a time base independent from the advanced timers.
  • Basic timers have no input/outputs and are used either as timebase timers or for
    triggering the DAC peripheral.
  • Low-power timers are simpler than general purpose timers and their advantage is the ability to continue working in low-power modes and generate a wake-up event.
  • High-resolution timers are specialized timer peripherals designed to drive power conversion in lighting and power source applications. It is however also usable in other fields that require very fine timing resolution. AN4885 and AN4449 are practical examples of high-resolution timer use.

Free PCB coupon via Facebook to 2 random commenters

BP

Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. The coupon code usually go to Facebook ‘Other’ Messages Folder . More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three times every week:

Continue reading “Free PCB coupon via Facebook to 2 random commenters”

Teardown, repair and experiments with the Anritsu 37347A 20GHz Vector Network Analyzer

Here’s another great video teardown from TheSignalPath:

In this episode Shahriar repairs an Anritsu 37347A 20GHz Two-Port Network Analyzer. The unit does not boot up and as a result its internal state is unknown. The boot fault is traced to a bad RTC module which has a built-in integrated battery. A replacement unit is located which allows the unit to fully boot.
The instrument initially displays an unlock condition on the internal PLL. This problem is resolved by loading the PLL calibration files from the HDD. The complete block diagram of the unit is examined in detail and an unusual PLL intermittent locking problems is demonstrated. Various measurements on several of the internal PLLs confirm their functionality. As a final experiments, the instrument is calibrated and the S-parameters of a tune-able band-pass filter is measured.

More details at The Signal Path homepage.

The AAduino

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Johan Kanflo has a new project posted the AAduino, that is available on Github:

The AAduino is an wireless Arduino clone the size of an AA battery with Keystone battery terminals rotated 180° to act as positive and negative terminals. It is powered by an ATMega328p and is fitted with an RFM69C companion. There is room for two DS18B20 temperature sensors and an indicator LED.

Project info at Johan Kanflo’s blog.

Eagle CAD tips and tricks

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Yahya Tawil from All About Circuits shares some Eagle CAD tips and tricks that you may not be aware of:

Most hobbyists and many professionals use Eagle CAD as a daily tool in designing schematics and laying out PCB. I’m going to share with you the most important tips and tricks for using Eagle CAD, which make my work much easier and faster.

More details at All About Circuits homepage.

Via the contact form.