#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 https://ift.tt/2L70xMX

ESP32 with multiple DS18B20 temperature sensors

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Guide to ESP32 with multiple DS18B20 temperature sensors from Random Nerd Tutorials:

This guide shows how to read temperature from multiple DS18B20 temperature sensors with the ESP32 using Arduino IDE. We’ll show you how to wire the sensors on the same data bus to the ESP32, install the needed libraries, and a sketch example you can use in your own projects. This tutorial is also compatible with the ESP8266 and the Arduino boards.

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Teardown of an MVMT dual USB port wall outlet adapter

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Kerry Wong did a teardown of an MVMT dual USB port wall outlet adapter:

Specification wise, the adapter is rated to provide 2.1A for its USB output. I did some load testing with an electronic load I built before and it appeared that the 2.1A is rated for the combined output from both USB ports. You can see my testing in the video linked towards the end of this post. This means that if you are charging two devices using this adapter, charging time will be lengthened as the 2.1A output current has to be shared between the two channels.
The internal build quality of this MVMT USB adapter is actually quite good. Two PCBs are used in this adapter. One is for surge protection and the other one is for the switching power supply that generates the 5V output rails.

See the full post on his blog here.

Check out the video after the break.

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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.

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App note: How to maintain USB signal integrity when adding ESD protection

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Introducing the eye diagram method in this app note from ON Semiconductors in determining signal integrity of USB lines. Link here (PDF)

The Universal Serial Bus (USB) has become a popular feature of PCs, cell phones and other electronic devices. USB makes data transfer between electronic devices faster and easier. USB 2.0 transfers data at up to 480 Mbps. At these data rates, any small amount of capacitance added will cause disturbances to the data signals. Designers are left with the challenge of finding ESD protection solutions that can protect these sensitive lines without adding signal degrading capacitance. This document will discuss USB 2.0 and evaluate the importance of low capacitance ESD protection devices with the use of eye diagrams.

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App note: Low-side self-protected MOSFET

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Integrated fault protected MOSFET app note from ON Semiconductors. Link here (PDF)

The ever increasing density and complexity of automotive and industrial control electronics requires integration of components, wherever possible, so as to conserve space, reduce cost, and improve reliability. Integration of protection features with power switches continues to drive new product development. The often open environments of automotive and industrial electronics, subject to severe voltage transients, high power and high inductance loads, numerous external connections, and human intervention force the requirement of fault protection circuitry. Advancements in power MOSFET processing technology afford an economical marriage of protection features, such as current limitation, and standard MOSFET power transistor switches. This paper describes the technology and operation of ON Semiconductor’s HDPlus monolithic low-side smart MOSFET family.

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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:

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.

from Dangerous Prototypes https://ift.tt/2KE5wZd

Building a USB bootloader for an STM32

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Kevin Cuzner writes:

As my final installment for the posts about my LED Wristwatch project I wanted to write about the self-programming bootloader I made for an STM32L052 and describe how it works. So far it has shown itself to be fairly robust and I haven’t had to get out my STLink to reprogram the watch for quite some time.
The main object of this bootloader is to facilitate reprogramming of the device without requiring a external programmer.

More details on Projects & Libraries’ homepage.

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Building a DIY SMT pick & place machine with OpenPnP

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Erich Styger has a nice write-up about building a DIY pick & place machine based on OpenPnP:

This article is about a project I have started back in January 2018. As for many of my projects, it took longer than anticipated.But now it is working, and the result is looking very good: a DIY automated pick and place machine to place parts on circuit boards. In the age of cheap PCBs, that machine closes the gap for small series of boards which have to be populated in a time consuming way otherwise.

See the full post on MCU on Eclipse blog.

Check out the video after the break.

 

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Silicon die analysis: Inside an op amp with interesting “butterfly” transistors

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An excellent in-depth look at theTL084 op amp by Ken Shirriff:

Some integrated circuits have very interesting dies under a microscope, like the chip below with designs that look kind of like butterflies. These patterns are special JFET input transistors that improved the chip’s performance. This chip is a Texas Instruments TL084 quad op amp and the symmetry of the four op amps is visible in the photo. (You can also see four big irregular rectangular regions; these are capacitors to stabilize the op amps.) In this article, I describe these components and the other circuitry in the chip and explain how it works. This article also includes an interactive chip explorer that shows each schematic component on the die and explains what it does.

See the full post on Ken Shirriff’s blog.

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