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App note: Simple test method for estimating the stability of linear regulators

อาทิตย์, 03/24/2019 - 20:00

Tips from ROHM Semiconductor to estimate the stability of linear regulator using simple step response method. Link here (PDF)

Low drop-out (LDO) regulators developed back in the age when large-capacitance multi-layer ceramic capacitors (hereinafter, MLCCs) were uncommon cause a phase delay, leading to oscillation when connected to a low-ESR capacitor like an MLCC. Often, MLCCs are used to save board space and prolong the lives of electronic components. A resistor placed in series in the circuit increases apparent ESR and establishes a phase lead that enable the use of an MLCC as an output capacitor. Phase margin measurement is practical on an LDO having variable output voltage, since its feedback loop is outwardly exposed. However, on a fixed output voltage LDO, the phase margin cannot be measured because of its closed loop circuit.

App note: Understanding the safety certification of digital isolators

เสาร์, 03/23/2019 - 20:07

This application note summarizes the international safety standards and certifications that apply to digital isolators. Link here

Digital isolators provide signal isolation and the level shifting required for the correct operation of many circuits. Equally important, they insulate the user from electric shock. With basic human safety considerations so pertinent here, these isolators must undergo extensive testing and certification to ensure user safety. This article briefly summarizes the international safety standards and certifications that apply to digital isolators. An example exercise using the MAX1493x family shows how an IC designer must use a data sheet and the standard’s specification tables to determine which digital isolator will be optimal for an application.

Op amp on the Moon: Reverse-engineering a hybrid op amp module

เสาร์, 03/23/2019 - 06:31

Ken Shirriff has written an article on reverse engineering a hybrid op amp module:

I recently obtained a mysterious electronic component in a metal can, flatter and slightly larger than a typical integrated circuit.1 After opening it up and reverse engineering the circuit, I determined that this was an op amp built for NASA in the 1960s using hybrid technology. It turns out that the development of this component ties connected several important people in the history of semiconductors, and one of these op amps is on the Moon.

See the full post on his blog.

Piggybacking USB onto an industrial push button

พุธ, 03/20/2019 - 22:28

Glen Akins has written an article detailing his USB-connected big red button project:

In this project, I mount the electronics from my single-key USB keyboard project to the back of an industrial mushroom push button switch. The finished big red button now activates my screensaver with a single overly-large button press. The biggest issues in this project were where to mount the USB electronics and how to connect the USB cable between the button and my computer.

More details on Photons, Electrons, and Dirt blog.

Resistive load, constant-current power supplies, and a 3D printed desk lamp

พุธ, 03/20/2019 - 06:50

Dr. Scott M. Baker published a new build:

In this video, I build a 3D Printed Desk lamp. The basic design came from Thingiverse, but I repurposed my LM2576 Constant-Current design to serve as a dimmer.  It all started when I found an interesting lamp on thingiverse, which used 75mm air hose segments from another model to make a flexible articulating desk lamp. What appealed to me about this project is the size of it, and the use of COB LED panels, which I’ve been wanting to experiment with.

See the full post on his blog.

Check out the video after the break.

Sound card ECG with AD8232

อังคาร, 03/19/2019 - 00:16

Scott Harden built a DIY ECG project with AD8232, that is available on Github:

Every few years I revisit the idea of building an ECG machine. This time I was very impressed with how easy it is to achieve using the AD8232, a single-lead ECG front-end on a chip. The AD8232 is small (LFCSP package) but breakout boards are easy to obtain online.

Project info at SWHarden.com.

Check out the video after the break.

Free PCB Sunday: Pick your PCB

จันทร์, 03/18/2019 - 04:00

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: Reset and supervisor ICs – frequently asked questions

จันทร์, 03/18/2019 - 00:00

All about supervisor ICs FAQs from STMicroelectronics. Link here (PDF)

App note: Receiving S/PDIF audio stream with the STM32F4/F7/H7 series

อาทิตย์, 03/17/2019 - 20:00

App note from STMicroelectronics about electrically connecting an external S/PDIF stream to an STM32 with an S/PDIFRX interface peripheral, Link here (PDF)

The Sony/Philips Digital Interface Format (S/PDIF) is a point-to-point protocol for serial and uni-directional transmission of digital audio through a single transmission line for consumer and professional applications. The transmission of data can be done in several ways, by electrical or optical means.

The S/PDIFRX peripheral embedded in STM32 devices is designed to receive an S/PDIF flow compliant with IEC-60958 and IEC-61937, which define the physical implementation requirements as well as the coding and the protocol. These standards support simple stereo streams up to high sample rates, and compressed multi-channel surround sound, such as those defined by Dolby or DTS.

App note: Addressing power supply challenges for after-market electronics and infrastructure

อาทิตย์, 03/17/2019 - 02:38

This application note discusses key market trends and customer needs that are presenting new challenges for power supply design for after-market technologies and transport infrastructure automation. This piece will also examine solutions to address these challenges, with a special emphasis on power architecture. Link here

After-market automotive products have driven remarkable innovation, from infotainment and telematics to advanced driver assistance systems (ADAS). Features like GPS, rear-view cameras, and parking sensors are now common in vehicles. There is also a continuous rollout of novel after-market technologies being developed by companies worldwide. Fleet management, on-board diagnostics, heads-up display, and freight control/monitoring are just a few examples of technologies found in cars and trucks, trains, ships, avionics, and defense applications.

Wifi based DIY 5V switcher for led-lights

ศุกร์, 03/15/2019 - 18:14

Albert posted a detailed how-to on building DIY ESP-12F based USB-5V switcher:

5V powered 100LED circuit was consuming around ~1.8Watts(though 5.1Ohm series resistor was really hot) and the brightness of the LED’s were not bad, especially difference between first led and last led brightness didnt bother me it was hardly noticeable when seen from distance. So I decided to use them as a christmas decoration for my garden.
I wanted to use them with battery-bank as there was no power-outlet readily available(for the safety of my children, i would avoid any 230v circuit in my garden especially in wet weather). Also I wanted them to be switchable remotely to avoid going out in the freezing cold. Hence this is what i came up with.. an “ESP-12F based USB-5V switcher”

See the full post on his blog.

So how to do CW on a homebrew SSB rig?

พุธ, 03/13/2019 - 20:47

Pete Juliano, N6QW, has written an article on how to do CW on a homebrew SSB rig:

The Answer is Not a Flippant: Carefully!
Author’s note: A friend in VK4 land made an inquiry about CW operation. I find that 99.99% of my operating time is SSB. But others spend a greater time on the air using CW so why not share some info and data that I have stashed on my computer where a SSB rig can be made to work CW. This also open the possibility of filter switching for a more narrow pass band. With Arduino anything may be possible.

More details on Pete Juliano’s (N6QW) blog.

Tiny particle sensor node with decorative case

พุธ, 03/13/2019 - 18:00

Lucky Resistor published a new build:

This article is about a small sensor node with a decorative case. It is based on the Raspberry Pi Zero W board with a custom sensor shield on top.
I publish all hardware files for a simple version of the sensor, so you should be able to build this kind of sensor nodes and use it to monitor anything you like. You can also extend/modify the design easily with additional sensors. Nevertheless, the case lid design is based around the Plantower PMSA003 particle sensor. It has all required air vents for this use.

More details on Lucky Resistor homepage.

App note: Bootstrap circuit in the buck converter

จันทร์, 03/11/2019 - 00:00

App note from ROHM Semiconductor about bootstrap capacitor used in switching regulator chip. Link here (PDF)

This application note explains the step-up circuit using a bootstrap capacitor. In buck converters, this circuit is used when the highside switch is the N-ch MOSFET.

App note: Linear regulator problem situations – Power supply does not start

อาทิตย์, 03/10/2019 - 20:00

App note from ROHM Semiconductor about various start up problem on 3 pins linear regulator. Link here (PDF)

Although linear regulators can be used to easily configure power supplies, the linear regulators may cause startup problems depending on the type of loads. This application note introduces cases where the power supplies do not start correctly in the linear regulators.

App note: Design considerations for a harsh industrial environment

เสาร์, 03/09/2019 - 20:37

This article discusses factors that influence the robustness of a circuit in a harsh environment, like you would find for industrial applications. The topics covered include ways to handle voltage transients and to protect against electrostatic discharge (ESD) and faults. Link here

Semiconductor (IC) robustness—what is the operating temperature range? How is high electrical noise handled? What about ESD and fault protection? These issues are not necessarily the first things that a design engineer thinks about when selecting an IC. Nonetheless, robustness is a key performance parameter for long-term operation and a reliable, reputable end product. This is especially true when designing a system for an industrial environment where harsh operating conditions are common. Industrial equipment can be exposed to a wide range of temperatures, high electrical noise on either the power-supply lines or data lines, and fault events like ESD or short circuits.

Remote debugging with USB based JTAG/SWD debug probes

เสาร์, 03/09/2019 - 06:40

Erich Styger wrote an article on how to turn a USB debug probe into a IP-based debug solution:

For some projects it is not possible to have the device under debug available on my desk: the board might be in another room, on another site or in a place where physical access is not possible or even dangerous. In that case an IP-based debug probe (see Debugging ARM Cores with IP based Debug Probes and Eclipse) is very useful: as long as I can access its IP address, that works fine. It is an excellent solution even if the board is moving or rotating: hook it up to a WLAN access point and I still can use it as it would be on my desk.

More details on MCU on Eclipse homepage.

Experiments with a Hydrogen Thyratron

ศุกร์, 03/08/2019 - 22:35

Kerry Wong did some experiments with a TGI1-50/5 hydrogen thyratron:

The one I picked up is a TGI1-50/5 hydrogen thyratron. As the name suggests, it uses ionized hydrogen gas as the switching medium. Hydrogen thyratron typically utilizes titanium hydride in it’s reservoir and the hydrogen gas is released when the reservoir is heated and recombined into titanium hydride when the temperature cools down. Like many other hydrogen thyratrons, the TGI1-50/5 has a separate heater for the hydrogen reservoir.

More details on Kerry Wong’s blog.

Check out the video after the break.

Raspberry Pi based indoor air quality monitor

พุธ, 03/06/2019 - 06:00

Dr. Scott M. Baker made this Pi-based environmental monitor and wrote a post on his blog detailing its assembly:

For years I’ve followed the “uRadMonitor”, a device that does air quality monitoring and radiation monitoring. I’ve played with geiger counter projects before and frankly found them to be not very interesting. However, the idea of monitoring air quality is something that seemed like it might yield interesting data. For example, as I’ve started to become involved in 3D printing, it would be useful to see whether or not 3D printing affected the air quality. It would also be useful to correlate my results with what my region reports for outdoor air quality.

Check out the video after the break.