App note: How to measure the power consumption of a peripheral


Application note from NXP Semiconductors on MCU peripheral power consumption measurement. Link here (PDF)

This Application Note outlines the steps to measure the power consumption of a peripheral and figure out some key points in the measurement. The document takes low-power timer (LPTMR) and LPUART as examples to introduce the method to measure the power consumption of peripheral. The test code is developed in IAR and FRDM-KE15Z board.

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App note: TEA1938T GreenChip SMPS control IC


TEA1938T SMPS control IC application note from NXP Semiconductors. Link here (PDF)

The TEA1938T is a high-featured low-cost DCM and QR mode flyback converter controller. It provides high efficiency at all power levels and very low no-load power consumption at nominal output voltage in burst mode operation.

To minimize ripple, the burst mode uses a small hysteresis scheme. The TEA1938T is designed to support multiple-output-voltage applications like USB PD (Type C) power supplies. Typical applications include notebooks and tablet adapters, fast charging, and direct charging adapters.

from Dangerous Prototypes

Teardown and repair of an Agilent E3632A DC power supply


Teardown and repair of an Agilent E3632A DC power supply from The Signal Path:

In this episode Shahriar & Rosanah investigate an Agilent power supply which does not appear to power on. It can be quickly observed that the fuse has failed on the unit. Using an isolation transformer a small amount of AC voltage is applied to the unit after the fuse replacement. It is clear that a short is present somewhere in the instrument since even at 10V AC the instrument consumes more than 1A.

See the full post at

Check out the video after the break.

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Free PCB coupon via Facebook to 2 random commenters


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:

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • We’ll contact you via Facebook 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.

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Build your own testing/programming jig


Sjaak has published a new build:

Inspired by an old article from sparkfun and some tests I conducted myself I came up with a PCB that holds the pogopinholders and an lasercut acrylic fixture for the PCB on top. Using the dirt(y)cheap services from the cost for this jig, including pogopins and their holders is about 45 USD. As an advantage you receive 5 lasercut acrylic and 10 PCBS which allows you to make 3-4 jigs in total!
To design the PCB that holds the pogopins I started with a 10×10 PCB with M3 mounting holes and imported the to be programmed PCB (File, Import, Eagle drawing) and place this in the centre (not mandatory, but looks prettier).

See the full post at

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DirtyPCBs adds full range of steel and framed stencils



Stencils for solder paste and red glue are now available in a bunch of standard sizes for solder paste/red glue dispensers. You can choose from all the options offered by our favorite stencil maker:

  • Purposes: Solder paste for surface mount component reflow process. Red glue for two-sided or through hole board wave soldering process
  • Alignment: quarter points for automated dispensers, and through hole for hand application
  • Polishing process: hand sanded (for most stuff) or electrolytic (for BGA footprints)
  • Engineering options: your paste layer (untouched), auto (China standard), auto with approval by PDF

We’ve been playing with the Neoden4 pick and place machine in a mini production line and needed a better way to order stencils with advanced options. Give us a shout if we missed any options you need!

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DirtyPCBs site update with encrypted https connections

1dirtypcbs now supports secure, encrypted access with We used a free certificate from Let’s Encrypt and the process was almost painless. You’ll need to add the ‘s’ to the address manually to access the secure version of the site.

Https may become the default eventually. It’s trendy to force everyone onto https these days, but China targets https traffic for slowdowns and blocking. The Shenzhen office has a much better experience using the non-encrypted http version so we’ll keep it around.

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WiFi TFT touch LCD weather station with ESP8266


Erich Styger built this ESP8266 WiFi weather station with touch LCD and wrote a post on his blog detailing its assembly:

After the “WiFi OLED Mini Weather Station with ESP8266“, here is another one: this time with Touch LCD 🙂  In the previous article (“WiFi OLED Mini Weather Station with ESP8266“) I have used the OLED kit from And as promised, this time it is about the “ESP8266 WiFi Color Display Kit”

Project info at MCU on Eclipse. Code is available on GitHub.

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Free PCB Sunday: Pick your PCB


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.

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App note: Using trench technology MOSFETs in hot swap applications


Safely use trench MOSFETs on hot swap application by determining its operation within its SOA in a limited time, app note from International Rectifier. Link here (PDF)

Hot Swap circuits are used to allow for “Hot Plugging” of circuit boards into back planes. The applications that require such functionality are mission critical, such as servers and communications equipment that must operate continuously. These circuit boards are usually employed in a rack mount system which consists of an array of boards that cannot be powered down. Thus hot swapping allows for a bad board in the array to be replaced without powering down the entire system.

In essence the Hot Swap circuit, which is between the board input rail and the rest of the board’s circuitry, is an inrush current limiter that allows for charging of the bulk capacitance in a controlled manner. Also faults, such as over current and overvoltage are managed by Hot Swap circuits.

from Dangerous Prototypes