rePalm

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rePalm project from Dmitry.GR

As I mentioned, none of the native API of PalmOS 5.x was ever documented. There was a small number of people who figured out some parts of it, but nobody really got it all, or even close to it. To start with, because large parts are not useful to an app developer, and thus attracted no interest. This is a problem, however, if one wants to make a new device. So I had to actually do a lot of reverse engineering for this project – a lot of boring reverse engineering of very boring APIs that I still had to implement. Oh, and I needed a kernel, and actual hardware to run on.

App note: Consideration of self pollution reduction for electronic systems

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App note from ON Semiconductors on EMI self pollution. Link here (PDF)

This application note will address the problem of Electro Magnetic Interference (EMI) self pollution in which one part of an electrical systems such as cell phones and consumer electrical products emit radiation that interferes with the operation of other parts of the system.

App note: 1 kV SenseFET integrated power switch

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App note from ON Semiconductors on their FSL4110LR power switch for SMPS power supplies. Link here (PDF)

Some industrial equipment that are supplied from a threephase AC power source such as industrial drives and energy meters often need an auxiliary power supply stage that can provide a regulated low-power DC source for analog and digital circuitry.

This power supply stage requests special specifications such as;
– Wide AC input voltage: 45 VAC to 460 VAC
– Robust system against high line surge
– Protection against magnetic contact test
– Large output capacitance to keep long hold-up timeafter power-off

Temperature/weather station

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B. Perry writes:

I’ve always been fond of the popular Nixie clocks made from old surplus Soviet nixie tubes. Nixie tubes are no longer made, so they’re hard to acquire. Instead, I took inspiration from “Lixie” displays and made my own Nixie-inspired, LED-powered display. And in an unusual twist (for me, anyway), I didn’t make a clock this time! It’s a weather/temperature display.  I made the parts myself, starting with the electronics. These circuit boards were created on the CNC machine. The “brains” are an ESP8266 chip, which grabs the current weather from the Internet.

See the full post in his blog.

A low cost 2-4 GHz Downconverter from off the shelf dev boards

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Ian Wraith designed and built a low cost 2-4 GHz downconverter for an SDR, that is available on Github:

I recently became interested in exploring some of the signals found in the 2.4 GHz ISM band. The problem is that my favourite SDR (Software Defined Radio) an Airspy R2 only covers up to 1.7 GHz. Initially I looked at buying an SDR that could cover the 2.4 GHz band but found either that they were to expensive , had poor performance or weren’t supported by my SDR control software of choice. So I decided it would be best to build a downconverter to take the 2.4 GHz down by 1 GHz so it could be monitored by my Airspy.

Via rtl-sdr.com.

MAKERVILLA 3.0

MAKERVILLA 3.0

MAKERVILLA is back! It will be held 31 July – 2 August 2019 at the National Design Centre Singapore.

MAKERVILLA 3.0 is a 3-day creative learning experience (CLX) design conference for local and international makers, practitioners & educators to gather under one roof for a time of learning, dreaming, hacking and sharing of ideas.

Find out more on their website at makervilla.com.  Mark your calendar!

#FreePCB via Twitter to 2 random RTs

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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.

6CY7 dual triode valve amplifier

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Josh built this 6CY7 dual triode valve amplifier:

I’ve always wanted to know what the “tube magic” was all about. There is much opinion in the science of music production, probably because music and its perception is highly personal and subjective. Ive always imagined that since transistor amplifiers were “perfect” with their large amounts of negative feedback, great linearity, and low THD that tube amplifiers must add something to sound that generates their appeal. From the reading I’ve done it has to do with harmonics.

More details on imsolidstate blog.

App note: Programmable analog functions

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Another app note from ON Semiconductors about various digital potentiometers application. Link here (PDF)

Analog circuits are made programmable by using digital potentiometers (POTs) to vary the key circuit parameters. This application note provides the analog design engineer with basic reference designs and circuit ideas for controlling the key parameters of analog circuits using digital POTs connected to a computer bus or microcontroller. Analog circuits are made programmable by using digital potentiometers (POTs) to vary the key circuit parameters. This application note provides the analog design engineer with basic reference designs and circuit ideas for controlling the key parameters of analog circuits using digital POTs connected to a computer bus or microcontroller.

App note: Digital potentiometer (POT) to control LED brightness

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Controlling LED brightness through digital potentiometer and a LED driver from ON Semiconductor. Link here (PDF)

Light-emitting diodes (LEDs) require a regulated current, and their brightness is proportional to the current that flows through them. Some LED drivers use an external resistor to set the LED current. A digital POT can replace a discrete resistor with the advantage of providing an adjustable value allowing the LED brightness to dynamically change. Most digital POT circuits have the ability to store permanently the resistor value in non-volatile memory.

Run a Korg SQ-1 Sequencer from a 9V Stompbox supply

 

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Run a Korg SQ-1 Sequencer from a 9V Stompbox supply:

The Korg SQ-1 is a great little sequencer, and one of my favourite bits of kit for its simple hands-on feel and penchant for lucky randomness (I have 3 of them!)
I tend to use it in a live setup with no computer but with a lot of guitar effect pedals on 9V daisy chain cables. The fact that the SQ-1 can only use batteries or USB power becomes a bit annoying so I decided to hack one so it can run on the same power supply as the pedals.

More details on Stuff and Nonsense blog.

Simple NTP clock using USB display module

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Dilshan Jayakody writes:

Simple NTP clock is a maintenance-free clock application developed to work on single-board computers like Raspberry Pi, Orange Pi, etc. This clock application uses the Simple Network Time Protocol (SNTP) to get the time and display it on seven segment display which I designed.  This application is designed to work on most of the Linux based systems and had minimum dependencies with system libraries and peripherals. I developed this application to work with Allwinner H2 Plus based Orange Pi Zero board, but this can compile for other platforms without doing any modifications on the source code.

See the full post on his 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.

Bitcoin mining on an Apollo Guidance Computer: 10.3 seconds per hash

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Ken Shirriff implemented the SHA-256 hash algorithm and ran it on the vintage Apollo Guidance Computer (AGC) that they’re restoring:

We’ve been restoring an Apollo Guidance Computer. Now that we have the world’s only working AGC, I decided to write some code for it. Trying to mine Bitcoin on this 1960s computer seemed both pointless and anachronistic, so I had to give it a shot. Implementing the Bitcoin hash algorithm in assembly code on this 15-bit computer was challenging, but I got it to work. Unfortunately, the computer is so slow that it would take about a billion times the age of the universe to successfully mine a Bitcoin block.

See the full post on Ken Shirriff’s blog.

‘No-Parts’ temperature measurement with Arduino Pro Mini

1 sec WDT interval timed with micros() vs si7051 reference temperature, to determine temperature variation of the RC based timer vs the crystal based timer, as a function of temperature

From the comments on our ESP8266 temperature logger post, Edward Mallon  writes:

The ESP8266 has a hardware watchdog timer, so you could probably use that to measure temperature to much better resolution that you’d get from a DS18B20. We get better than 0.003C using the technique with cheap Pro Mini Clones
Ooops, I missed an important aspect of the two clock method – the inter-reading jitter in the micros() reads brings the resolution down to DS18b20 levels.

More details on Underwater Arduino Data Loggers blog.

App note: High density serial flash addressing

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Old app note from Macronix about accessing high density serial flash. Link here (PDF)

Many consumer products have converted or are converting from parallel flash to SPI serial flash. Generally, high end applications require higher memory density, but in the past, serial flash densities were limited to 128Mb due to addressing constraints.

App note: USB On-The-Go (OTG) basics

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USB OTG explained in this app note from Cypress Semiconductors. Link here

This application note discusses several aspects of OTG functionality. The note introduces end-applications and different types of cables and connectors involved with OTG. It also describes the OTG protocol state changes when both Mini-A and Mini-B devices are connected .The host negotiation protocol (HNP) and session request protocol (SRP), which are part of the OTG protocol, are also explained.

Acorn BBC Master and electron cartridge breakout

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The Acorn Master cartridge breakout board by Simon Inns:

This project provides a simple breadboard adapter/breakout board for prototyping cartridges for the Acorn BBC Master and Acorn Electron 8-bit computers.
The design consists of two PCBs, the first plugs into the computer’s cartridge slot and the second is designed to plug along the edge of a standard 2.54mm pitch breadboard.  The two boards are connected by a length of 50-way ribbon cable.

Project info at waitingforfriday.com and GitHub repository here.

USB seven segment display module

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Dilshan Jayakody published a new build:

This project is about an open source, USB based, 10 digit seven segment display unit. This unit is specifically designed to work with POS systems and banking applications. Initially, this system is developed to work with PC based systems, and later it was modified to work with other platforms and applications.

See the full post on his blog.