Avoccado° Nora, batch of PCB from DirtyPCBs

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Natalie Kane writes:

Nora is the most recent approach to cram up everything of the recent prototypes but use only 2 layers and populate all of the components on one side. Nora is the smallest board with a LiPo charger yet, measuring just 23.5 mm x 23.5 mm.
Nora is the first version having the IRQ (or ‘interrupt’) from the nRF24L01+ radio connected to the micro controller. Additionally, the accelerometer and gyroscope IRQ is also connected to the micro controller, which was not the case with the Avoccado° prototypes before.

Designing and building a 2m low pass filter

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Kenneth made a 2m low pass filter and wrote a post on his blog detailing its assembly:

I’ve been playing with the DRA818V modules that have been making quite a stir in the amateur radio world at the moment. I haven’t gotten one on a spectrum analyzer yet, but I have reason to believe that it will require a low pass filter to be RF legal. I’ll write more about that once I get a look at it, but figured I’d first built myself a low pass filter in case I need it (if not for these modules, but some other VHF project in the future).
My process for building a low pass filter went as follows:

  • Select the type of filter and cutoff frequency desired
  • Look up normalized coefficients in the ARRL Handbook
  • Divide these coefficients by the cutoff frequency
  • Convert the inductances into turns on some core and capacitors into the nearest values
  • Build the filter

WiFi LED Light (ESP8266 + WS2812B + Lua)

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Markus Gritsch shared his WiFi LED light project in the forum:

I built a prototype for a WiFi controllable LED light, using the popular ESP8266 module running the NodeMCU firmware [1]. To allow controlling the WS2812B LEDs from Lua, I extended the firmware with a bit of C code

Check out the video after the break.

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Review and teardown of the Analog arts SL987 USB oscilloscope AWG pattern generator and Logic analyzer

Review and teardown of the Analog arts SL987 USB oscilloscope AWG pattern generator and logic analyzer by Shahriar of TheSignalPath:

In this episode Shahriar takes a close look at the Analog Arts USB based mixed-domain instrument. The SL987 offers an oscilloscope, arbitrary waveform generator, FFT-based spectrum analyzer, pattern generator and logic analyzer in a compact form factor.
The teardown of the unit is presented along with the datasheet of every major component on the PCB. Some design limitations and concerns are presented along with basic performance verifications.

 

SL414 Vintage power amplifier IC

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Dilshan Jayakody  writes:

SL414 is combined audio preamplifier and power amplifier IC manufactured by National semiconductors in early days. This amplifier is designed to operate in 10V to 20V range and deliver 3W (R.M.S) audio output power into 7.5Ω load. The frequency bandwidth of this IC is between 30Hz to 18kHz and with 8Ω load it produces 0.5% T.H.D on 3W.
The most uncommon feature of this IC is its EP-10 package. This EP-10 package is common to most of SL4xx series amplifiers and thanks to its inbuilt screw it is really easy to attach heat-sinks to these ICs.
During our prototyping, we try several SL414 amplifiers and most of them give quiet satisfactory results to us. Link to most stable SL414 design is available at the bottom of this article. As per our experiments, to archive best results it is mandatory to build this amplifier on PCB with screened wires. Also to get the good results make sure to drive this amplifier with regulated DC power supply. In our tests we use LM317 base PSU to drive this amplifier.

Files available at elect.wikispaces.com.

#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.

Diolan plus2 – Diolan bootloader with standard instruction set

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nyholku writes:

To support my EazyCNC Project I I’ve create a version of the original Diolan bootloader that I call ‘diolan-plus2’ and which does not use extended instruction set making it compatible with C-compilers and still retains all the features of the original diolan bootloader and fits in the 2kB bootblock.

Diolan-plus2 published on GitHub.

Via the forum.

PICnano Breadboard, a 4-Layer Dirty PCB project

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jechavarria shared his small 4-layer board based on the PIC18F2550 microcontroller project in the forum:

The goal of this new design is try to have an Arduino Nano compatible module but with some new features, such have direct access to the power supply microcontroller.

Via the project log forum.

Temperature controller for K-type thermocouple and MAX6675

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Chris Holden of Nerd Club has written an article on their DIY temperature controller with a simple menu system:

After what seems to have been a very long time, it was nice to poke more wires into a breadboard and make something actually useful for a while! Here’s a simple temperature monitor for our injection moulding heater block. It uses three buttons for setting the parameters and some pretty dodgy-looking routines to detect “short” and “long” presses

Digital data capture unit with EMF reader

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Dilshan Jayakody writes:

This is PIC16F73 base digital data capture unit with optional EMF reader. This data capture utility is design to work with most of the analog sensor inputs and by default it is equipped with EMF reader module. This unit use PIC16F73’s internal 8bit ADC to capture the analog signals.
EMF reader unit in this schematic is useful to detect variations of EM field in environment and it is mainly build around uA741 operational amplifier and 12mH detector coil. Normally EMF meters are used to trace electric wires, find hidden transmitters, and diagnose electric wiring problems (and to find ghosts too ☻).

All files and codes are available at elect.wikispaces.com.

MoteinoMEGA pick & place assembly

In this video Felix of LowPowerLab demonstrates a complete pick & place assembly of a MoteinoMEGA panel:

The main things to take from this video are:

  • effective CPH (components per hour) rating is affected in large by several factors like travel from pick position to placement position, travel speed, mechanical alignment in X and Y directions, vision alignment of each board, pick retries, dropped components, feeder reloading, feeder/tape jams, and many others.
  • some components require a medium pick/travel speed and fine settle placement because they are “special” and may flip or get misaligned.

 

Teensy SDR project

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rheslip made this Teensy SDR project, that is available at Github:

I managed to get the Teensy SDR in an enclosure over the Christmas holidays – now its starting to look like a radio!
The enclosure is a plastic Hammond. Front and rear panels are PCB material and I added a layer of PCB inside to mount the boards and help with shielding. Front panel mounts the 1.8″ TFT display, two buttons for the UI, micro USB from the Teensy 3.1, Teensy audio shield headphone jack, an encoder for tuning and a pot for volume. Back panel has antenna and power connectors and a couple of holes for the speaker/mic I intend to use.

Check out the video after the break.

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App note: Output current sensing for the MC07XS6517 and MC17XS6500 eXtreme switch devices

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An app note(PDF) from Freescale Semiconductor

This document describes the current sense performance of eXtreme switches, and describes the enhanced current sense mode dedicated for low current loads, such as light emitting diodes (LED). This application note also presents the accuracy for 7.0 mOhm and 17 mOhm channels, and the practical implementation of a calibration procedure to get optimized results.

The eXtreme switch is the latest achievement in automotive lighting drivers. It consists of a scalable family of devices compatible in software, MCU interface, and footprint. This product family is designed for low-voltage automotive and industrial lighting applications. This high-side power switch family includes the MC07XS6517, which is designed to drive a wide range of light sources, including HID ballasts, incandescent bulbs, or LEDs.

Programming, control, and diagnostics are accomplished using a 16-bit SPI interface, which provides a large panel of configuration, analog, and digital information related to the device in its application, and a full set of protection features to ensure its safety. All information provided by the SMARTMOS through the SPI gives the MCU all the key information to reflect device and output status. This device also provides a wide flexibility of configurations in addition to highly sophisticated fault and failure mode handling.As an example, it integrates an enhanced PWM module with 8-bit duty cycle capability. Each output has an independent prescaler to control PWM frequency, phasing, and outputedge shaping, to improve electromagnetic compatibility.

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:

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App note:Coils used for wireless charging

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An app note(PDF) from Freescale Semiconductor on wireless charging coil designs

There are many battery-powered devices, which need to be periodically charged, such as mobile phones, tablets, and battery-powered hand tools. These tools are usually charged by a dedicated cord from a USB port or from a dedicated wall adapter.

Wirelessly transferred power simplifies the charging of these devices and brings more convenience to the everyday lives of our customers. Dedicated controllers are required for wireless charging application control.

Freescale provides the WCT1xxx family of the dedicated controllers for the wireless charging applications. Each type is intended for a certain range of applications in the automotive or industrial and consumer area. Freescale provides the dedicated wireless charging software library intended for these controllers. This library maintains all functions required by the Qi specification.

TAPR/DCC video: System on a Chip – Programming FPGAs for Mixed Signal Systems

Here is the first of a four-part video series recently posted from the 2014 TAPR/DCC conference in Austin, TX. This is from the DCC’s Sunday Seminar, “a four-hour deep dive” into a single subject, in this case FPGA programming for mixed signal systems.

“The presenter is amateur radio operator Chris Testa KD2BMH who is designing the Whitebox, the “HT of the Future.” It will be a multi-mode, multi-band ham radio that will look and work more like a smartphone: touchscreen display, apps, and all the analog and digital modes he can stuff in (and license). Chris is working with Bruce Perens K6BP on the Whitebox project. An FPGA will be the heart of the Whitebox radio, and its programming will be the brain. Chris explains in as much detail as a four-hour talk allows just what it takes to do that programming.”

The remaining videos can be found on YouTube under the HamRadioNow channel where they are made available thanks to the efforts of Gary Pearce KN4AQ.

App note: Lateral mosfet design recommendations for audio amplifiers

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Semelab’s application note on lateral mosfet design recommendations for audio amplifiers:

Semelab’s range of lateral mosfets has been specifically designed for audio power amplifiers and there are a number of advantages that they exhibit over bipolar transistors in these applications. This application note is intended to highlight these differences and give design guidelines in using the mosfets for high power audio products.
Semelab’s new range of Alfet devices are available in both single (8Amp) and double-die (16Amp) versions with complementary Nchannel and P-channel parts rated at both 160V and 200V.

Automated drill press table for PCB manufacture

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A DIY automated moving drill press table by Michael of Acidbourbon:

When you design your PCBs with a proper CAD software (such as KICAD), you have the coordinates of all drill holes anyway, so how about making an automated moving drill press table which moves the PCB to the places where holes are desired? But calibrating the coordinate system on the PCB should be quick and reliable.

Check out the video after the break.

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