FPGA-based disk controller for Apple II

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Steve Chamberlin over at Big Mess o’Wires has been working on an FPGA-based disk controller for Apple II, which he call Yellowstone:

Apple II disk controller cards are weird, there are a crazy number of different types, and many are rare and expensive. Can an FPGA-based solution save the day for retro collectors? You bet! Nearly all the existing disk controllers connect the same 8-bit bus to the same 19-pin disk interface, so a universal clone is merely a question of replacing the vintage 80s guts of the card with a modern reprogrammable FPGA. This hypothetical universal controller card could connect to almost any Apple II disk drive, or a Floppy Emu. Here’s my first attempt.

More details at Big Mess o’ Wires homepage.

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ESP32lights

ESP32lights

Luca Dentella published a new build:

Today’s project, ESP32lights, is a smart device based on the esp32 chip.
Thanks to ESP32lights you can turn a load on and off (I used it for my christmas lights)

  • manually
  • based on daily schedules
  • based on the light intensity

ESP32lights connects to your wifi network, can be configured and operated via a web browser and it’s optimized for mobile devices (responsive web interface based on jQuery Mobile).

Full description on his blog. More tutorials about the ESP32 chip here.

Check out the video after the break.

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Common emitter amplifier design tips & shortcuts

Tips & tricks for the common emitter amplifier design by Alan Wolke (aka W2AEW)

This video provides some basic design tips and shortcuts for the Common Emitter, Class A, Amplifier. The considerations for selection of the DC Bias point are presented, as well as some tips on how to set/compute the gain for both degenerated and high-gain configurations.

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Yet another ARM development tutorial

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ARM development tutorial at smdprutser.nl:

It has been a while since I wrote about ARM development. I recently made a Black Magic Probe (BMP) clone which acts different then the original. The BMP can source power to the target, but on my version control signal is inverted. Not a big deal, but can give unintentional results and has to be fixed. Just for my own memory I wrote down all the steps involved in setting it up and shared it in order to be useful for others.

See the full post on smdprutser blog.

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#FreePCB via Twitter to 2 random RTs

BP

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.

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Easing the pain of SWD on modern DPS:es

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Johan Kanflo writes:

On newer DPS:es, the SWD connector is a JST-GH (1.25mm spacing that is) which translates to “really tiny”. The annular rings where you need to apply solder and heat for adding wires are even smaller. This is why the OpenDPS SWD Bottle is handy. Add three P50-E2 pogo pins, and connect to your favourite SWD debugger.

See the full post on his blog.

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Free PCB Sunday: Pick your PCB

BP-600x373

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: High-Power backup

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App note from Murata on application of Electrical double layer capacitors (EDLCs). Link here (PDF)

When you consider backup function in your product, Murata’s supercapacitors (also known as EDLCs, Supercaps) are suitable for backup energy device. Murata’s supercapacitors can discharge in high power up to 10A. Therefore they can cover wide range of backup function that is from low power for long time to high power for short time. And you can design Murata’s supercapacitors into your slim devices because of the thin thicknesses. In addition, because supercapacitors have longer cycle life than batteries, they have potential for maintenance free.

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App note: Lithium Ion Capacitors: An Effective EDLC Replacement

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Hybrid capacitor of EDLC and LIB, Lithium Ion capacitors from TAIYO YUDEN offers solution to conventional EDLC lesser characteristics. Link here (PDF)

EDLCs were first created in Japan in the 1970s and began appearing in various home appliances in the 1990s. Since the 2000s, they have been used in mobile phones and digital cameras. EDLCs are typically used to protect against sudden momentary drops or sudden interruptions in power. They can instantaneously output large amounts of power, while a battery cannot. They are frequently used as backup power sources in servers and storage devices for integrated circuits, processors, memory and more.

While EDLCs are intended to be backup power sources, conventional EDLCs suffer from a phenomenon known as self-discharge, where the capacitor will gradually lose its charge over time. Self-discharge can occur more rapidly during exposure to high temperature environments. The extremely low self-discharge of an Lithium Ion Capacitor, even in high heat environments, ensures a long-lasting charge.

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