MQTT/JQUERY/WebSockets controller

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Peter Scargill writes:

I wrote a while ago about using web sockets as against something like NETIO for controlling the home – most folk liked the article but I think part of it was a little complicated – and at the time I’d not really thought it out to make it as simple as possible.
So, this morning I started again and now I have a decent and easy way to make control interfaces from the mobile phone – to ESP boards. I won’t go into MQTT in detail here – I’ll assume you have an MQTT interface of some description on your WIFI boards – if you need more info on that, look elsewhere on the blog.

Yet another Bus Pirate free PCB build

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idpromnut built a free Bus Pirate v3.8 PCBs. The Bus Pirate is an open source hacker multi-tool that talks to electronic stuff.

If you build a free PCB we’ll send you another one! Blog about it, post a picture on Flicker, whatever – we’ll send you a coupon code for the free PCB drawer.

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

Via the forum.

Check out the video after the break. Continue reading “Yet another Bus Pirate free PCB build”

Using input impedance to measure current

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Using input impedance to measure current, see the detailed blog post here from Sigzig:

Input impedance on measurement equipment is usually kept as high as it can in an effort to prevent loading down the signals the equipment is measuring. For example most general purpose digital multimeters aim for an input impedance of at least 1M ohm. The Zig-4 has a lower input impedance of 330k ohms but this is still high enough for many/most situations. That being said it is still important to understand input impedance and its affect on your measurements.
In this post I thought it would be fun to actually take advantage of the 330k input impedance of the Zig-4 as a sort of low current sensing.
The goal: To see if we can use the Zig-4 to detect a change in current in the very low nA range.

Bus Pirate v3.8 free PCB build

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Mark Stewart built two free Bus Pirate v3.8 PCBs.  The Bus Pirate is an open source hacker multi-tool that talks to electronic stuff.

If you build a free PCB we’ll send you another one! Blog about it, post a picture on Flicker, whatever – we’ll send you a coupon code for the free PCB drawer.

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

Via Twitter.

A JTAG/XSVF library for Arduino

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Marcelo published a post on his blog about JTAG and the library he wrote.

I have recently felt the need to incorporate a JTAG port in a project to program a hardware that contained a CPLD. The idea was to both program it and perform some integrity tests on the board. I imagined something using pogo pins, to make it easier and quicker to test everything. I would also write the necessary test routines and generate some kind of report.
With this objective in mind, I have decided to design an Arduino shield to do the job. The testing routines were not really a big deal. And I was sure I would find some JTAG library for Arduino ready to be used. That was not the case.
There were some projects using Arduino to control a JTAG TAP (Test Access Port), but they were all incomplete. And I had no idea what was really JTAG. So I had to study a little bit to make things work for me.
In the end, the challenge proved enlightening. There were some caveats, both from hardware and from software. I’ll try to address them in this article.

The library is hosted on Github.

More details at Marcelo’s EE & CS blog.

Testing the Shinyei PPD42NS

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From the comments on our Arduino dust sensor post,  KH writes:

The sensor can obviously measure dust concentrations, it also has to be placed and set up properly, and it gives useful readings. For hobby users like most of us, obviously calibration to specific or absolute standards will be almost impossible.

More details at Darell Tan’s blog.

Via the comments. Thanks KH!

 

 

#FreePCB via Twitter to 2 random RTs

KHOS-2-3-4-5-6P 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.

50W LM3886 power amplifier

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A 50W LM3886 power amplifier project from Electronics-DIY:

This is a second revision of 50W LM3886 power amplifier that is used to power two bookshelf speakers. The sound produced by LM3886 chip is excellent so I decided to make another amplifier with it. The schematic is based on the schematic in the datasheet of the chip with minor changes. I removed the time delay capacitor connected to MUTE pin, because it’s better to use separate DC protection schematic which has similar functionality. I made the output inductance L1 by winding 15 turns of enameled wire around the resistor R7. The diameter of the wire must be minimum 0.4mm. The whole was wrapped with heat shrink.

More details at Electronics-DIY site.

Mearm forked

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Bajdi’s self designed version of the mearm using 3 stepper motors:

Since I was not very happy with the original design I decided to make my own version. Goal was to make it much simpler to print, less pieces that don’t need to be so accurate to fit together. I used freecad to design my robot arm. Long time ago I used Solidworks at work and freecad is a bit similar in workflow. Did not take me long to design the arm. My mearm is a little bigger then the original version.
I recently found some cheap 28-byj-48 stepper motors that are rated at 12V (1.48$ @ Elecrow). So I decided to use those stepper motors instead of servos. I only use a servo for the gripper.

Project info at Bajdi’s project page.

Check out the video after the break.

Continue reading “Mearm forked”

Yet another scanning Monochromator build

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Kerry D. Wong writes:

A while ago, I saw a video on the signal path in which Shahriar modified his Verity EP200Mmd monochromator/detector and turned it into a scanning monochromator. Inspired by his work, I decided to do something similar. Since I do not have the equipment to make the mechanical pieces, I decided to take another route. In this post, I will show you a simple and non-intrusive way to make the EP200Mmd a scanning monochromator. A video discussing the build and some experiments is included towards the end.

More details at Kerry Wong’s project page.

Check out the video after the break. Continue reading “Yet another scanning Monochromator build”

App note: Bi-directional translator architectures

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Voltage translation app note from Fairchild Semiconductors, this app note include their auto bi-directional voltage translator that removes the burden of direction control. Link here (PDF)

Voltage translators, or “level shifters” as they are sometimes called, allow the coupling of signals that do not share common VCC domains. For example, a signal generated from a 1.0 V device may need to connect to a 3.3 V device.

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:

Continue reading “Free PCB Sunday: Pick your PCB”

App note: Reset timers

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Reset timers application note from Fairchild Semiconductors. Link here (PDF)

As smart phones continually add functionality, it increases the likelihood of device lock up. This condition has been called the “White Screen of Death” which is a new take on the popular phrase used to describe Windows PCs after a system fault. Before the advent of standalone reset timers, users were required to remove the phone battery to force a device restart. As more device suppliers remove access to the device battery, it has become necessary to provide a more convenient way of forcing a device reset.
Reset timers create a failsafe mechanism for users to reset the phone using a single- or multiple-button long key press. Reset timers have an advantage over software solutions in that the independent, hardware-based solution is not susceptible to software crashes. The need for hardware-based reset timers is the result of an increased likelihood that device operating systems can be derailed by the growing applications and features they must support.

App note: Typically testing “Typical” in a typical manner

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Typically testing “Typical” in a typical manner,  app note here (PDF!) from Maxim:

Typical (typ) is typically the most misunderstood word in Integrated Circuit (IC) testing. Typical values can’t be tested directly because they are a statistical value. We discuss how to read a data sheet to understand what parameters are tested and under what conditions. Fabrication (fab) parameters are highlighted including process standard deviation, fab process corners, six sigma quality guard bands, and defective parts per million opportunities (DPMO) concepts.

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:

Continue reading “Free PCB coupon via Facebook to 2 random commenters”

Geiger counter with SBM20 tube

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j3tstream writes:

I “rebuild” my Geiger counter, the SBM-20 tube was initially inside the box, i have put this one inside a 32mm diam plastic tube, for more convenience, wired through a XLR3 cable. This counter is from “Electronique-Pratique” n°368, a french electronic magazine. Shem, pcb, and PIC hex & C source code available.

More details at Weird-Lab blog.

Raspberry Pi garage door controller

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As a follow up to yesterday’s Raspberry Pi and ARM uC Breakout + DirtyPCBs mini-review post,  hipfan75 has posted the completed Raspberry Pi-based Garage Door controller project:

The whole project started after a technician from Urgent Garage Doors pointed out that our two-bay setup had no remote monitoring whatsoever — a gap that felt embarrassing once he named it. Right now, all of the sensors and actuators are connected to Raspberry Pi GPIOs, though at some point I may migrate them to the STM32.

I’ve disabled I2C on the Pi and repurposed the SDA/SCL pins as standard GPIO, leaning on the external pull-up resistors already on those lines to handle sensor pull-ups — the sensors run active-low, so the existing hardware played nicely with that decision. GPIO 17, 27, 22, and 23 (all configured as outputs) carry the light and door toggle signals for both garage doors.

Project info at hipfan75 imgur.   Reddit discussion here.

Continue reading “Raspberry Pi garage door controller”

Lowpass filter for 30m

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Flathagen made a 30m lowpass filter for his Softrock Ensemble RXTX tranceiver:

I just finished a 30m lowpass filter for the Softrock Ensemble RXTX tranceiver.  I used the schematic provided by WB5RVZ.  L200 and L201 is wound to about 0.9uH, whereas C200 and C202 is 100pF and C201 is 330pF. Everything is soldered to a PCB (ugly construction) and I added two switches and a coax to enable on and off switching of the filter.

 

Arduino dust sensor

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Shadowandy’s Arduino-based Dust Sensor project:

Put together a dust sensor using Arduino Mega 2560, Shinyei PPD42NS dust sensor and LCD shield.

The codes and wiring instructions for Arduino Mega 2560 and Shinyei PPD42NS is as follow. However, I did include Serial output so you can view the sampling results using Arduino IDE’s Serial Monitor (9600 bauds).

Project info at Shadowandy’s blog.

 

Raspberry Pi and ARM uC Breakout + DirtyPCBs mini-review

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hipfan75 writes:

Briefly, it’s a Raspberry Pi v1, Model B, Rev2 breakout with an STM32F030 microcontroller connected to the Pi UART, with all GPIOs for both broken out. There are also connectors for an NRF24L01+ module, a 12V boost module, and 315/433 Mhz wireless transmitters.
One board will serve as my Garage Door Controller, while the others will be used for general Pi hacking.
This was my first board manufactured at DirtyPCBs.com. I was very impressed with both the ordering and fulfillment process, as well as the boards themselves.

Reddit discussion here.