FPGA-based disk controller for Apple II

yellowstone-in-600

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.

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. Continue reading “ESP32lights”

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.

Yet another ARM development tutorial

armdevelopment-1056x675

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.

#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.

Easing the pain of SWD on modern DPS:es

IMG_0501-225x300

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.

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:

Continue reading “Free PCB Sunday: Pick your PCB”

App note: High-Power backup

an_murata_high_pwr_backup

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.

App note: Lithium Ion Capacitors: An Effective EDLC Replacement

an_taiyo_yuden_licap2

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.

Free PCB coupon via Facebook to 2 random commenters

BP

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”

Dirty terminal sample pack

header

Crimp Terminals for Cables

Crimp terminals lock to the end of a wire and attach to an electrical connection such as a screw or terminal block. There are tons of different styles out there, but we found a handful that every Chinese cable manufacturer stocks. This is important because while reels of crimps are cheap, each crimp uses different tooling and manufacturers only buy tooling for the most common crimps.

In the previous post we covered commonly used JST and Molex compatible parts from the Shenzhen markets. These connectors come in two parts: a metal crimp that attaches to the wire, and a plastic crimp housing that holds all the crimps in place. This post looks at common crimp terminals that don’t use a plastic housing. Get the sample kit here, or build your own custom cables here.

Ring terminals

ring-set

These super common crimps attach to a bolt or screw terminal block. Four sizes are super common in the market and all fit a corresponding metric bolt size: 3.2mm (M3 bolt), 4.2mm (M4), 5.2mm (M5), 6.2mm (M6). Smaller and bigger sizes are available, but the crimps are rarely stocked so you’ll generally be on the hook for MOQ if you stray from this safe range.

Our manufacturer recommends 18AWG wire for all crimp terminals.

Spade terminals

spade-set

Spade or fork terminals attach easily to a bolt or screw terminal without fulling removing the screw from the terminal. We only found these in 3.2mm (M3) and 4.2mm (M4) in the market.

These work with common screw terminals and grounding bolts, but we found these really nifty PCB mount connectors (through-hole) with a single screw terminal. The manufacturer has a range with parts numbers from PCB-1 to PCB-14 that vary primarily in the height of the leads. PCB-2 is the most compact and lowest profile version, so we’ve been working with it.

Our manufacturer recommends 18AWG wire for all crimp terminals.

Blade terminals

blade-set

Male and female blade terminals connect cables to board mount connectors AND cables to other cables. Available in multiple sizes, but 2.8, 4.8 and 6.3 are the common.

There are multiple type of terminal blocks for connecting female blade connectors to PCBs or wiring harnesses. We found single PCB mount connectors (through-hole) for use with female blade crimps. The smallest versions (2.8) use 0.5mm thick metal, while the 4.8 and 6.3 version use thicker 0.8mm metal. The two bigger connectors have offset tabs to provide additional stability.

Our manufacturer recommends 18AWG wire for all crimp terminals.

Other crimp terminals

A lot of available crimp terminals are missing from this list: male and female bullet connectors, right angle blade connectors, etc. A reel of these crimps is not expensive, but most cable manufacturers don’t have the proper tooling work with them in their crimping machines. Crimp tools can range from $100 to $1000s, depending on the machine and if the manufacturer has to customize the tools.

If you’re looking to do low volume cheaply, the it’s always best to use what multiple manufacturers and distributors have available in the market.

Insulated covers

All three types of crimp terminals have compatible insulators in multiple colors. We’re not yet equipped to offer these in the dirty cables creator.

Maximum ratings

Please note that we’re unable to provide maximum ratings at this time. Our cable suppliers don’t have datasheets for the common “duff” stuff they’re using, so you’ll need to do the same due diligence on the final cables that you would if buying directly in China yourself.

We’ll need to find our own crimp terminal manufacturer and supply parts to the cable maker ourselves to get properly rated parts.

Touch it yourself: Dirty Terminals Sample Pack v1.0

Buy the kit. Can’t wrap your head around it without getting your hands on these parts? Don’t worry, we’ve got you covered. All these crimp terminals and mating connectors are available in the Dirty Terminal sample pack. Grab it in the store for $4.95.

Dirty Cables: Get your own custom cables

DirtyPCBs

Get cheap custom cables for your project, direct from Huaqiangbei. Use the Dirty Cable creator to drag and drop wires and connectors into a cable and price custom cables from quantity 100.

Taking it further

In the coming weeks we’ll cover coaxial power connectors and LED strip sockets.

Teardown of a 65W Cree LED bulb

CreeLEDBulb

Kerry Wong did a teardown of a 65W Cree LED bulb:

Upon removing the glass bulb enclosure, I was a bit surprised to see that only two power LEDs were used in this Cree bulb. Typically, you would see many more lower wattage LEDs put together to achieve higher wattage ratings. The two power LEDs are wired in series. Each power LED likely consists of eight to ten LED dies inside as the forward voltage drop of these two LEDs is measured at around 70V in operation, with each dropping around 35V. There is also a reverse polarity protection diode integrated into each of these power LEDs.

See the full post on his blog.

Check out the video after the break. Continue reading “Teardown of a 65W Cree LED bulb”

Tiny, isolated USB to Xcvr interface (PTT, Audio, CAT, …)

block

Mare writes:

I will describe here the USB interface between the radio station and the computer which I recently developed and tested. This post is a continuation of the first part, where I described a simple interface for controlling two digital lines using the USB / Serial Converter, where I presented simple interface to control two digital signals (e.g. Ptzt and CW). This time I will describe an interface that combines more functions:

  • Controlling several digital (switching) inputs and outputs
  • Interface for controlling the station via the serial interface
  • Audio input and output interface (sound card)

More details at Mare & Gal Electronics site.

ZeroBoy – A poor man’s retropie “portable”

img_20171222_181831

A nice build log of ZeroBoy portable retropie project, that is available on Github:

You know when you see something and it give you instant inspiration and you also see a few ways you would also improve it. The thing I seen was wonky resistor score zero it’s basically a raspberry pi “hat” that has buttons in the layout of a nes controller. What I first thought was to make my own “hat” but flip it 180 degrees and add pass though pins so I could add a screen on top of that. Joint me below for my journey I went though.

More details at Facelesstech site.

Check out the video after the break. Continue reading “ZeroBoy – A poor man’s retropie “portable””

App note: Capacitor selection guidelines on LDOs

an_analog_AN-1099

They are different kind of capacitors, selection for one capacitor varies depending on application. A good read app note from Analog Devices. Link here (PDF)

Capacitors are underrated. They do not have transistor counts in the billions nor do they use the latest submicron fabrication technology. In the minds of many engineers, a capacitor is simply two conductors separated by a dielectric. In short, they are one of the lowliest electronic components.

It is common for engineers to add a few capacitors to solve noise problems. This is because capacitors are widely seen by engineers as a panacea for solving noise related issues. Other than the capacitance and voltage rating, little thought is given to any other parameter. However, like all electronic components, capacitors are not perfect and possess parasitic resistance, inductance, capacitance variation over temperature and voltage bias, and other nonideal properties.

These factors must be considered when selecting a capacitor for many bypassing applications or where the actual value of the capacitor is important. Choosing the wrong capacitor can lead to circuit instability, excessive noise or power dissipation, shortened product life, or unpredictable circuit behavior.

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:

Continue reading “Free PCB Sunday: Pick your PCB”

App note: Linear regulators reverse voltage protection

an_rohm_linearreg_reverse_voltage_appli-e

Various input and output reverse voltage protection method for linear regulators discussed in this app note from ROHM. Link here (PDF)

A linear regulator integrated circuit (IC) is a DC-to-DC buck converter system that reduces a DC supply from higher voltage level to a lower voltage level, thus it requires that the input voltage is always higher than the regulated voltage. Output voltage, however, may become higher than the input voltage under specific situations or circuit configurations, and that reverse voltage and current may cause damage to the IC. A reverse polarity connection or certain inductor components can also cause a polarity reversal between the input and output terminals. This application note provides instructions on reversed voltage polarity protection for ICs.

Bit-banding explained: A key feature of ARM Cortex-M3/M4

bit-band_Cortex-M3-Memory-map

Yahya Tawil over at Atadiat wrote in to let us know about a corner-stone feature in ARM Cortex-M3 processors called bit-banding:

Writing a portable code is one of the concerns for developers, and while dealing with bit-fields is not standard in all compilers, it is not very advisable to use.
When a feature is available in the hardware itself, you will not have any issues in porting the code from vendor to vendor while both are using the same ARM Cortex-M3 core.

ARM Cortex-M3 features a 1 MB area in SRAM memory called bit-band region. In this region each bit can be accessed individually. To access to bit-band region bits you need to do so via an aliased region, where each word in this region is an alias to one bit in the bit-band region.

More details at Atadiat homepage.

Via the contact form.