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Feather M0 express supersizing

Posted on Friday, October 20th, 2017 in hacks by DP | No Comments

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Dastels writes, “In my last post I described how I hacked a 2Mbyte SPI flash onto a Trinket M0 to give it the memory space for CircutiPython of one of the M0 Express boards. This time I supersized an M0 Express board, specifically a Feather M0 Express, although the same hack should work on a Circuit Playground Express.”

More details at Curmudgeoclast site.

Free PCB coupon via Facebook to 2 random commenters

Posted on Friday, October 20th, 2017 in Free PCBs by DP | No Comments

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:

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Recovering Proxmark3 with the Bus Pirate

Posted on Friday, October 20th, 2017 in Bus Pirate by DP | No Comments

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@joan_bono tweeted, “Breathing again! My Proxmark3 works like a charm after re-flashing the firmware using Bus Pirate

Get your own handy Bus Pirate for $30, including world-wide shipping. Also available from our friendly distributors.

A digital communication project using OFDM and 32-QAM

Posted on Thursday, October 19th, 2017 in digital radio data, SDR by DP | 1 Comment

1OFDM system

Tahmid blogged about a digital communication project using OFDM and 32-QAM as their ECE4670 final project:

This builds on a previous lab, where orthogonal frequency division multiplexing (OFDM) is used with on/off keying to send data over the channel. This scheme achieved a data rate of about 14,000 bits per second with zero errors, resulting in a figure of merit of about 14,000. The high performance design utilizes orthogonal frequency division multiplexing (OFDM) and quadrature amplitude modulation (QAM) to achieve a figure of merit much higher than the previous lab.
The overall OFDM system block diagram is shown below (taken from Professor Wagner’s course’s Scribe notes)

See the full post on his blog.

Pulse Oximeter functionality for a medical device

Posted on Wednesday, October 18th, 2017 in Arduino, tutorials by DP | No Comments

Pulse Oximeter on my finger-600

Alexander Lang writes:

The gentlemen for whom I’m developing this hardware for has requested some additional functionality. The additional functionality requested is a Pulse Oximetry measurement.  Pulse Oximetry is the measurement of a person’s pulse along with how much oxygen is present within their blood.  It is a common measurement made by medical practitioners to ensure their patients are in good health.  I suspect for the medical device, this information will be correlated with a person’s breathing to assess how well a person’s lungs are working and how much oxygen from the air is getting into their blood.

See the full post on his blog here.

Teardown, repair and analysis of an Agilent E4443A 3Hz – 6.7GHz PSA series Spectrum Analyzer

Posted on Tuesday, October 17th, 2017 in repair by DP | No Comments

Teardown, repair and analysis of an Agilent E4443A 3Hz – 6.7GHz PSA series Spectrum Analyzer from The Signal Path:

In this episode Shahriar repairs an Agilent PSA Series Spectrum Analyzer. The instrument generates many errors during self-alignment and produces no measurements below 3.2GHz. The block diagram of the unit is thoroughly presented and various possible failure points are considered. Based on the observation of the noise floor, the most likely cause is the second LO module. The measurement of the LO power indicates that the second LO power is fall below nominal.

More details at The Signal Path homepage.

ZX81 internal 16K RAM (reversible version)

Posted on Tuesday, October 17th, 2017 in how-to by DP | No Comments

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Dave Curran wrote a post on his blog showing how he upgrades the ZX81 internal 16K RAM with a reversible version:

One of the common issues with the ZX81 is the good old RAM pack wobble. Depending on the state of your edge connectors on your ZX81 and RAM pack, it sometimes does not take much to interrupt one or more connections and crash the ZX81.
To get around this, I have done many ZX81 internal RAM upgrades, following the procedure I described in an old blog post – ZX81 Internal 16K RAM.
I had a request to do one of these, but to do it in a reversible manner, without cutting tracks.

See the full post on his blog- Tynemouth Software.

PSOC – design and implementation of a 12 lead portable ECG

Posted on Monday, October 16th, 2017 in builds, gadget by DP | 1 Comment

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Alex Lao and his team at McMaster University have developed a compact, battery powered, 12-lead electro-cardiogram:

During the academic year of 2016-2017 at McMaster University, in conjunction with Dr. DeBruin, Christina Riczu, Thomas Phan and Emilie Corcoran, we developed a compact, battery powered, 12-lead electro-cardiogram. The project won 1st place in the biomedical category at the ECE Capstone Poster Day.

More details at Voltage Divide’s homepage.

App note: Implementation of a single-phase electronic watt-hour meter using the MSP430AFE2xx

Posted on Sunday, October 15th, 2017 in app notes by DP | No Comments

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Another energy meter from Texas Instruments using MSP430AFE2xx. Link here (PDF)

This application report describes the implementation of a single-phase electronic electricity meter using the Texas Instruments MSP430AFE2xx metering processors. It includes the necessary information with regard to metrology software and hardware procedures for this single chip implementation.

App note: Atmel AVR465: Single-phase power/energy meter with tamper detection

Posted on Sunday, October 15th, 2017 in app notes by DP | No Comments

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A good read from Atmel on their 8-bit microcontroller single-phase energy meter design. Link here (PDF)

This application note describes a single-phase power/energy meter with tamper logic. The design measures active power, voltage, and current in a single-phase distribution environment. It differs from ordinary single-phase meters in that it uses two current transducers to measure active power in both live and neutral wires. This enables the meter to detect, signal, and continue to measure reliably even when subject to external attempts of tampering.

Free PCB coupon via Facebook to 2 random commenters

Posted on Friday, October 13th, 2017 in Free PCBs by DP | 1 Comment

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:

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A two channel SI5351 signal generator

Posted on Thursday, October 12th, 2017 in RF by DP | No Comments

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DuWayne Schmidlkofer has a nice write-up on building a two channel SI5351 signal generator:

After getting the sketches written for the SI5351 board written to support multiple display types, I decided I need to write one more. Now that Pete is moving the Simpleceiver to a single conversion super-het, I will have to worry about the BFO as well as VFO frequency.  Since I will probably use a different crystal frequency than Pete for the IF filter, I need to have a way to find the correct BFO frequency for both upper and lower side band. The easiest way to do that is to write a sketch that uses the 5351 as a two channel signal generator,with independent control of both frequencies.

See the full post on his blog.

Simulating 3-phase AC for energy monitor testing

Posted on Thursday, October 12th, 2017 in DIY, testing by DP | No Comments

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Tisham Dhar blogged about his 3-phase synthesizer:

Finding 3-phase is difficult, convincing the owner of the said supply to test some home made hardware is even more so. After building a 3-phase energy monitor my testing options for it appeared very limited. So I set about making my own low-cost 3-phase energy monitor calibration system.

See the full post on his blog.

Check out the video after the break. (more…)

SMA solar readout

Posted on Wednesday, October 11th, 2017 in ARM, LCD by DP | No Comments

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Jean-Claude writes:

This is the first post of a 3-part series about reading out an SMA solar inverter over Bluetooth and displaying some readings every few seconds. Long-time readers may remember the Solar at last weblog post from several years ago and the SMA Relay, based on a JeeNode v6. The Bluetooth readout code was derived from Stuart Pittaway’s Nanode SMA PV Monitor code.
This project is for a friend who’s birthday is coming up shortly, and who has the same SMA 5000TL inverter as I do – although it can probably be used with other models.

Project info at Jeelabs.org.

Vintage MIDI: Roland MT-32, Roland SC-55, HardMPU, and an Xi 8088

Posted on Wednesday, October 11th, 2017 in hacks, vintage by DP | No Comments

Dr. Scott Baker writes:

In this video, I decided to upgrade my home built PC from AdLib sound to MIDI. I tried out a couple different midi modules, the Roland MT-32 and the Roland SC-55. I learned that I’d need an MPU-401 or compatible ISA interface, and I explored the alternatives, eventually settling on the HardMPU by Ab0tj. Using the HardMPU schematic, I built a board, programmed the microcontroller, and tried out Vintage games on my Xi 8088. I also wrote my own Midi player to play .MID files using MPU-401 intelligent mode.

See the full post on his blog.

#FreePCB via Twitter to 2 random RTs

Posted on Tuesday, October 10th, 2017 in Free PCBs by DP | No Comments

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.

PICKit 3 Mini

Posted on Tuesday, October 10th, 2017 in PCBs, PIC by DP | 5 Comments

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Reviahh has published a new build, the PICKit 3 Mini:

Previously, I made a Pickit 3 clone – (see previous blog post). It works well, but I have often wondered just how little of its circuitry was needed to program and debug the boards I make. For instance – I primarily use the newer 3.3V PIC32 processors, so I really don’t need the ability to alter the voltage like the standard Pickit 3 can. I also have no real need for programming on the go, or even to provide power to the target MCU to program. Knowing this – I decided to see what I could do to remove the circuitry I didn’t need, yet still have a functioning programmer/debugger.

See the full post at DIY PCB homepage.

Modifying a computer ATX power supply for higher output voltage

Posted on Monday, October 9th, 2017 in hacks by DP | 1 Comment

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Kerry Wong wrote a post on his blog showing how he modified the 12V rail of a TL494 based ATX power supply to 14.6V for 4S LiFePO4 battery charging:

To charge the 110Ah battery bank I built, I need a power supply that can provide at least 10A at 14.6V. Since I have many old ATX power supplies lying around and the 12V rails of these power supplies are more than capable of providing 10A, I decided to modify one such power supply for using as a 4S LiFePO4 battery charger.

More details at his blog here.

Check out the video after the break. (more…)

App note: Capacitance change with applied DC voltage

Posted on Sunday, October 8th, 2017 in app notes by DP | No Comments

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Tantalum comparison to other types of capacitors shows stable capacitance in this app note from Vishay, Link here (PDF)

Tantalum capacitors in general – and Vishay’s 298D/TR8/TM8 MicroTan tantalum capacitors in particular – demonstrate very stable performance over the DC voltage (bias) applied in an application. At the same time, the majority of capacitors utilizing ceramic or polymer dielectrics (monolithic ceramic, disc ceramic, MLCC, polyester, film, etc.) demonstrate significant shift in both directions – sometimes 40 % to 50 % or higher

App note: Extend current transformer range

Posted on Sunday, October 8th, 2017 in app notes by DP | No Comments

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Design note from Texas Instruments on technique in resetting and negative voltage generation from current transformers. Link here (PDF)

Transformers are used extensively for current sensing because they can monitor currents with very low power loss and they have wide bandwidth for good waveform fidelity. Current transformers perform well in applications with symmetrical AC currents such as push-pull or full bridge converter topologies. In single-ended applications, especially boost converters, problems can arise because of the need to accurately reproduce high duty factor, unipolar, waveforms. Unipolar pulses may saturate the current transformer and, if this happens, overcurrent protection will be lost and, for current mode control, regulation will be lost and an over voltage condition will result.

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