App note: Circuit configuration options for TVS diodes

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Different TVS configuration usage app note from ON Semiconductor. Link here (PDF)

Transient Voltage Suppression (TVS) protection is important because EMI and ESD can disturb the operation of the system, produce permanent damage or cause latent damage that will eventually cause a failure. Avalanche TVS diodes and diode arrays are available in a number of different circuit configurations to protect electronic circuits from surge voltages. This document will analyze the attributes and trade-offs of different circuit configurations created with avalanche TVS and diode array protection devices.

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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.

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Emulating a hardware ROM in real time with an STM32F4

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ROM emulation using an STM32F4:

I remember reading dhole’s  Emulating a GameBoy Cartridge with an STM32F4 some time ago thinking that it had a lot of applications with respect to old computers. In that article  a STM32F4 microcontroller  ‘pretends to be a ROM chip for a gameboy’. At the start of a bus cycle, an interrupt is triggered in the STM32F4, it then reads the address bus of the gameboy’s 6502, checks the gameboy’s read/write line(s) and pulls data from its internal Flash and presents it onto the data bus long enough for the gameboy to read it, then tristates the databus. There are no wait states. It does this all within the 1000ns of the 1MHz Gameboy CPU clock. For all intensive purposes the gameboy thinks it has a real rom chip attached.

Full details at Kernelcrash.com .

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Bit-bang FTDI USB-to-serial converters to drive SPI devices

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Scott W Harden writes , “The FT232 USB-to-serial converter is one of the most commonly-used methods of adding USB functionality to small projects, but recently I found that these chips are capable of sending more than just serial signals. With some creative programming, individual output pins can be big-banged to emulate a clock, data, and chip select line to control SPI devices.
This post shares some of the techniques I use to bit-bang SPI with FTDI devices, and some of perks (and quirks) of using FTDI chips to bit-bang data from a USB port. ”

See the full post on Scott Harden’s blog .

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 select an ambient light sensor for your end equipment

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Another application note from Texas Instruments about ambient light sensors and how to effectively use them. Link here (PDF)

Generally, when someone thinks of trying to design a system with an ambient light sensor there are four main concerns or problems that need to be addressed. The most important features of an ambient light sensor are spectral response, power, size, and range of lux measurement.

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App note: How to isolate signal and power in isolated CAN systems

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CAN system isolation app note from Texas Instruments, Link here (PDF)

With the increase in the usage of signal isolation in many industrial and automotive applications, the need for isolated power has also increased. The benefits of isolation are lost if the power supplies on either side of the isolation barrier are simply shorted. At the same time, if the isolated power sub-systems are not designed carefully, it affects the overall system performance like temperature rise due to poor power transfer efficiency, data corruption due to emissions, and so on. To simplify the design process of isolated CAN sub-systems, this document provides various options (discrete and integrated) to isolate CAN signals and power.

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ESP32 and the CWTD ‘Test gadget’

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DuWayne published a new build:

I have been following a series of podcasts from ‘Chatting with the Designers’  CWTD.ORG that cover building simple Arduino based test equipment.  I decided that this would make a nice way to get into development with the ESP32.  The CWTD ‘Test Gadget’ is basically an Arduino Nano with a 2 line LCD display, and a breadboard area where small modules can be plugged in to make different types of instruments.  My version will use the ESP32 and the TFT display.  I am also replacing their rotary encoder with a joystick for the user interface device.  I am bringing all the pins from the ESP32 module out to two pairs of female headers, that should allow me to plug in two small modules at the same time.

See the full post on DuWayne’s Place blog.

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Siglent SDG6000X Series Arbitrary waveform generator review, teardown and experiments

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A closer look at the newly released Siglent SDG6000X Series Arbitrary Waveform Generator from The Signal Path:

The full teardown of the unit reveals the internal architecture of the instrument, DAC / FPGA interconnect as well as the output amplifier structure. Although the limitations of the FPGA prevents the instrument to operate at full 2.5GSa/s in arb-mode, the instrument is capable of providing complex modulation up to the full 500MHz signal bandwidth.

More details on The Signal Path blog.

Check out the video after the break.

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Transistor radio series: the AF power amp

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Vasily Ivanenko @ QRPHB writes, “I sought a low distortion, single supply, AF power amplifier for my transistor radios. I’ll present my experiments, some musings, test equipment and a reference to some wonderful books & their wise author. Sadly, some amateur radio receiver builders diligently craft their RF stages, but skimp on the PA audio stage. Actually — many commercial radio designers also do this.”

More details at QRP HomeBuilder blog.

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