Free PCB Sunday: Pick your PCB

IRToy

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: Dithering in analog-to-digital conversion

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e2V’s application note about dithering, adding noise to improve the dynamic range of ADCs. Link here (PDF)

High-speed ADCs today offer higher dynamic performances and every effort is made to push these state-of-the art performance through design improvements and also through innovative solutions at the system level.

For applications where the performance of the high-speed ADC in the frequency domain is the main critical parameter for the system overall performances, it is possible to improve the ADC response thanks to dither.

Dithering can be defined as adding some white noise, which has the effect of spreading low-level spectral components.

In this application note, the technique of dithering is presented, described and illustrated thanks to test results performed in the 10-bit 2.2Gsps ADC AT84AS008 device.

App note: Power MOSFET in high-side operating modes, possible failure modes, and failure signatures

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App note from Vishay on high-side MOSFET failures investigation leads to one of the following modes of operation:
(a) High-impedance gate drive
(b) Electro-static discharge (ESD) exposure
(c) Electrical over-stressed (EOS) operation

More on it here (PDF)

Power MOSFET failures in high-side applications can often be attributed to a high-impedance gate drive creating a virtual floating gate, which in turn increases the susceptibility of the MOSFET to failure during system-generated ESD and EOS scenarios.

App note: Power MOSFET Basics: Understanding the Turn-On Process

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More to know about MOSFET gate threshold voltages, an application note from Vishay. Link here (PDF)

The question of how to turn on a MOSFET might sound trivial, since ease of switching is a major advantage of field-effect transistors. Unlike bipolar junction transistors, these are majority carrier devices. One does not have to worry about current gain, tailoring the base current to match the extremes of hfe and variable collector currents, or providing negative drives. Since MOSFETs are voltage driven, many users assume that they will turn on when a voltage, equal to or greater than the threshold, is applied to the gate. However, the question of how to turn on a MOSFET or, at a more basic level, what is the minimum voltage that should be applied to the gate, needs reappraisal with more and more converters being controlled digitally. While digital control offers the next level of flexibility and functionality, the DSPs, FPGAs, and other programmable devices with which it is implemented are designed to operate with low supply voltages. It is necessary to boost the final PWM signal to the level required by the MOSFET gate. This is where things begin to go wrong, because of the misconceptions about what really turns on a MOSFET. Many digital designers look at the gate threshold voltage and jump to the conclusion that, just as with their digital logic, the MOSFET will change state as soon as the threshold is crossed.

Reverse engineering the ESP8266 WIFI-to-Serial port adapter

Here’s a video from electronupdate on reverse engineering the ESP8266 WIFI-to-Serial port adapter:

Another very interesting bit of technology. The combination of so much functionality into such a small part is a real touch-stone as to where things are heading.
A quick look at the antenna design to see if I could sort down the details and then some die-decap to analyze the silicon a bit. The RF section is especially interesting. In the video I call out a section as being an inductor… on second thought as I type this it might even be a transformer?
Amazing…

More details at electronupdate blog.

INA219 current sensor DIY Breakout board

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A INA219 current sensor DIY Breakout board project from Juan Ignacio:

Another small board, this time for a INA219. The INA219 is a high-side current shunt and power monitor with an I2C interface.
For testing I used Rei VILO library with a MSP430G2553 and Energia, and I measured the power consumption for this simple circuit.

Project info at ssihla homepage.

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”

Creating high resolution integrated circuit die photos with Hugin or ICE

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Ken Shirriff has written an article describing a technique he used for making high resolution integrated circuit die photos:

Have you ever wanted to take a bunch of photos of an integrated circuit die and combine them into a high-res image? The stitching software can be difficult, so I’ve written a guide to the process I use. These tips may also be useful for other Hugin panoramas.

More info at Ken Shirriff’s blog.

Ultimate classic game console joystick to USB adapter

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Matthew Heironimus posted a step by step guide of his “ultimate” classic game console joystick to USB adapter build:

This article describes how to use an Arduino Leonardo or Arduino Micro to make up to three classic console joysticks (e.g. Atari 2600, ColecoVision, and possibly others) available to a modern computer (e.g. Windows PC, Mac, or Linux). This adapter can be placed into one of the following modes:

* Joystick Mode
Each of the three classic console joysticks appear as a Game Controller.
* ADAMEm Mode
Configured for use with the ADAMEm emulator. Joystick 1’s direction and fire buttons are mapped to a Game Controller and the keypad is mapped to the keyboard’s numeric keypad keys. Joystick 2 is mapped to keyboard keys (e.g. up arrow key, down arrow key, etc.). This allows ADAMEm to support two player games. Joystick 3 is not used in this mode.
* MAME Mode
Configured for use with the MAME emulator. All three joysticks’ direction and fire buttons are mapped to the three Game Controllers. The numeric keys on all three joysticks are mapped to keyboard keys.

Project info at Heironimus’ blog.

Over the top UCload

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Sjaak has published a new build, uC controlled dummy load:

I’m mostly a digital guy, but I’m wanting to design my own power supply. If I’m wanting to test that i need a dummy load. I got inspired by the re:load (www.arachnidlabs.com/reload ). I added a microcontroller, rotary switch, external powersupply input and the obligatory 128×32 OLED :)

Project info at smdprutser.nl.

Via the project log forum.

ESP8266 WiFI LED controller hack

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Andreas Hölldorfer of ChaozLabs wrote an article detailing how he hacked the cheap WiFi LED controller:

This pictures show the PCB. As you can see there are pins labeled as RX,TX,GND,3.3V. I simply connected an USB-Serial converter to the pins. The two other pins are GND and GPIO0. If you set a jumper between this two pins, the controller starts in bootloader mode.
The chip above is a NXP HC245, a 3-state Octal bus transceiver. It is used to drive the N-channel MOSFETS (20N06L – 20 A, 60 V, N−Channel DPAK).
The power supply is a 2 stage design. A AOZ1212 3A Simple Buck Regulator to convert the input voltage to about 5V and an AMS1117 low dropout voltage regulator to get 3.3V.

More info at ChaozLabs site.

Check out the video after the break. Continue reading “ESP8266 WiFI LED controller hack”

#FreePCB via Twitter to 2 random RTs

KHOS-2-3-4-5-6P 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.

Adding a USB power port to a switch for IoT

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Jesus Echavarria wrote a how-to on adding a USB power port to a switch:

I want to start some projects with Arduino and IoT, so the first things I need is an Arduino board, an Ethernet shield and a switch to connect it to the net. Also I need a power supply for the Arduino board, and I think that, better than a external USB AC wall adaptor or power supply, is modify the switch to add it a USB power port that can power the Arduino board. I’ve got at home a TP-Link TL-SF1008D, a simple 8 port 10/100 Mbps switch. So, let’s go to open it and add it the USB port!

More info at Echavarria’s blog.

Via the contact form.

Keysight EXA Signal Analyzer/Spectrum Analyzer review, teardown & experiments

Another video review from TheSignalPath, Keysight EXA Signal Analyzer/Spectrum analyzer:

In this episode Shahriar reviews the Keysight EXA Signal Analyzer / Spectrum Analyzer (N9010A). The X-Series Signal Analyzers and Spectrum analyzers from Keysight are compared against each other. The EXA is a general purpose spectrum analyzer with extensive applications.
The full instrument block diagram is presented with focus on various signal paths and frequency planning. Several of internal modules (RF Front-End, Digital Baseband Processor and LO Synthesizer) are also presented and compared with the block diagram. In order to examine the instrument’s capabilities in a real-world situation, a complete superheterodyne wireless transceiver with a sliding-IF receiver is design and examined. Each individual component in the system (LNA, mixer, PLL, etc.) are individually characterized by using the EXA Signal Analyzer. The complete system measurements are also presented.

More info at TheSignalPath homepage.

Arduino Zero using a xQFP80 +50 Protoboard

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Tom Keddie shared his Zero project using a xQFP80 +50 Protoboard:

I need more processing power than an AVR for an upcoming project so I ordered an Arduino Zero to take a look at the SAMD ARM processors. Unfortunately my son coveted the box it came in, once the two were separated the Zero was never seen again. I had separately ordered the processor part, I realised I could build a Zero using a spare DP xQFP 50/80 prototyping board.
The schematic is fairly simple, doesn’t even need an external crystal. I was extra pleased when I realised the 1.27mm header fit the SOIC pattern on the board.

Via the project log forum.

xQFP protoboards are available in 0.50mm, 0.65mm, and 0.80mm+0.50mm for $10.

 

App note: High speed data line protection

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Bridge diode works as transient voltage clamp to protect data lines. Here’s Vishay’s app note, link here (PDF)

Local Area Network (LAN) data lines require protection against direct and induced transient over voltages on the lines. Protecting these lines and the associated network is not a trivial task. The power range is somewhere between static discharge (very low power) and lightening protection which is at the other end of the spectrum (high power).

Power handling capability is only one aspect of the design. The designer must take care not to “load down” the line with a highly capacitive TVS or R/C network. As data rates go beyond 50 mb. It is not possible to use a TVS unit with capacitance above 100 pF to 200 pF. Most standard TVS devices have zero volt capacitance values greater that 500 pF. To make matters worse, the lower voltage TVS units have higher capacitance values than their higher voltage counterparts.

Free PCB Sunday: Pick your PCB

IRToy

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”