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Guitar Amp builder notes — AF power amplifier dummy load

Posted on Wednesday, December 12th, 2018 in DIY, tools by DP | No Comments

DSC_2129-1 (1)Vasily Ivanenko has written an article detailing his AF dummy load project:

I’ll describe a simple 8, or 4 Ω dummy load to test your home brew guitar power amplifiers.
Low cost 16 Ω / 25W wire wound, aluminum shell, chassis mount resistors seem abundant.  I got mine on eBay.  Wire wound resistors vary in quality, design and tolerance. Some even exhibit low inductance by winding with an Ayrton-Perry bifilar technique.  Resistor tolerances range from 10% down to ± 0.5 % + 0.05 Ω.  Typical manufacturer power ratings are done at 25C, however, these devices are meant to sit on a heat sink when used and that’s why the aluminum housing contains 2 relatively large mounting holes.

Project info on QRF HomeBuilder blog.

Building a direct conversion receiver

Posted on Tuesday, December 11th, 2018 in DIY, how-to by DP | No Comments

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Ryan Flowers over at MiscDotGeek posted a how-to on building a direct conversion receiver:

In the first installment of this series, we discussed why we’re building a Direct Conversion receiver and talked about some basic ideas. In this installment, we explore what it takes to make the leap from a printed schematic to something physical that works. Follow along!

More details at MiscDotGeek.com.

App note: BLDC with hall effect sensors using SCT on LPC84x

Posted on Sunday, December 9th, 2018 in app notes by DP | No Comments

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Motor control on LPC84x MCU app note from NXP. Link here (PDF)

This application note describes an implementation of brushless DC motor control with hall effect sensors using the SCTimer/PWM on LPC84x.

App note: Ambient light sensor SFH5701

Posted on Sunday, December 9th, 2018 in app notes by DP | No Comments

an_osram_sfh5701

App note from OSRAM on their ALS device SFH5701, its operation and application method. Link here (PDF)

The SFH5701 is a small, two-wire, linear output current ambient light sensor (ALS) with current amplifier and dark current compensation. The ALS is capable of resolving a wide range of ambient light levels (10 mlx – 10 klx) tailored to the spectral response of the human eye and operational from -40 °C to 100 °C.

Free PCB coupon via Facebook to 2 random commenters

Posted on Friday, December 7th, 2018 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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Battery switch

Posted on Friday, December 7th, 2018 in open source by DP | 1 Comment

featured

An open source battery switch project from Open Electronics:

Given two batteries, it chooses the one to connect to the load based on the voltage measured at their poles. It can also be used to switch DC power supplies.

More details at open-electronics.org.

Teensy 3.6 as standalone mediator between USB MIDI and Eurorack

Posted on Friday, December 7th, 2018 in Arduino, how-to by DP | No Comments

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Sebastian writes:

USB MIDI controllers (such as Launchpad Mini Mk II for example) are common and often quite low in cost.
To interface such a controller with a Eurorack synth system, often a host computer and a MIDI to CV interface might be used. The host computer would take USB MIDI data from the MIDI controller, perhaps store and manipulate that data in some way (e.g. a sequence), using a MIDI to CV converter to then control a Eurorack synth system.
It would be useful to use USB MIDI controllers with Eurorack synth systems without needing a computer and MIDI to CV interface in between the two.
Teensy 3.6 is a great microcontroller that can be programmed using the Arduino IDE. A very useful feature of the Teensy 3.6 is the USB host port.

See the full post on his blog here, Little-Scale.

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

New 2.5D pen/laser ESP32 controller

Posted on Thursday, December 6th, 2018 in open source, wireless by DP | No Comments

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Bdring published a new build:

I have done several pen and laser machines lately, so I decided to create a custom PCB for Grbl_ESP32 for these types of machines. This is a small (70mm x 60mm) PCB with all the features a pen plotter or laser cutter/engraver would need.
These typically use stepper motors for the X and Y axes. On pen plotters, the Z axis is controlled by a servo or solenoid. On lasers you need an accurate PWM for laser power control.

Project info at Buildlog.Net blog and the library GitHub repository here. It’s also up on Tindie.

USB Mass storage device bootloader

Posted on Thursday, December 6th, 2018 in PIC by DP | No Comments

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MPPT Solar charger’s USB mass storage device bootloader project from Soldernerd, that is available on GitHub.

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

#FreePCB via Twitter to 2 random RTs

Posted on Tuesday, December 4th, 2018 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.

DakBoard family calendar with Raspberry Pi Zero W and Read Only filesystem

Posted on Tuesday, December 4th, 2018 in DIY, R-Pi by DP | No Comments

DakBoard Family Calendar

Scott Hanselman made this DakBoard family calendar with Raspberry Pi Zero W and wrote a post on his blog detailing its assembly:

The implementation is simple genius. It’s a browser that starts up full screen (kiosk mode) and just sits there and updates occasionally. DakBoard provides the private webpage and tools to make that happen. You can certainly build this yourself with any number of open source tools. I chose DakBoard because it was simple, beautiful, and I was able to get the whole thing done in less than an hour. I’m sure I’ll spend many hours tweaking it through. There’s also the very popular MagicMIrror platform, so lots of choice and power in this space!

See the full post on his blog here.

The OpenBrite Turbo controller for Vectrex

Posted on Monday, December 3rd, 2018 in DIY, vintage by DP | No Comments

Vectrex Controller Prototype

Stephen Wylie blogged about his Turbo Vectrex controller build:

 The main impetus for this was to have a homebrew controller that actually featured an analog joystick, since there were few if any guides elaborating how to fashion one from an existing controller.  I acquired a couple Parallax 2-axis joysticks with breadboard mounting capability to do the trick.
The Vectrex comes with a game in its ROM — Asteroids — thus you can play without needing a cartridge.  However, with the traditional controller, this requires lots of button-mashing since it has no auto-fire feature.  Using a 555 timer, potentiometer, and clever values within an RC circuit, I have given it the ability to auto-fire.

See the full post on his blog here, GOSHtastic.

Free PCB Sunday: Pick your PCB

Posted on Sunday, December 2nd, 2018 in Free PCBs by DP | 5 Comments

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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: Low-current charger provides battery backup from USB to 1-cell applications

Posted on Sunday, December 2nd, 2018 in app notes by DP | No Comments

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Another app note from Maxim Integrated on small current battery management. Link here (PDF)

The circuit provides a 1-cell Li ion backup battery charger for low-current devices performing resistor limited current sharing

App note: How to achieve greater accuracy in battery capacity readings for portable designs

Posted on Sunday, December 2nd, 2018 in app notes by DP | No Comments

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App note from Maxim Integrated on using fuel gauge IC to obtain accurate battery state of charge readings. Link here (PDF)

Because a product’s runtime is limited by battery capacity, it’s critical to have a precise method for measuring the remaining battery capacity to avoid an unexpected shutdown. This application note describes an experiment for obtaining accurate battery capacity readings in a dog-tracking project.

Free PCB coupon via Facebook to 2 random commenters

Posted on Friday, November 30th, 2018 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:

(more…)

Teardown and repair of an GW Instek PSW80-40.5 1080W multi-range programmable power supply

Posted on Friday, November 30th, 2018 in power supply, Teardowns by DP | No Comments

GW Instek

Teardown and repair of an GW Instek 1080W power supply from The Signal Path:

In this episode Shahriar investigates the failure of a GW Instek 1080W power supply capable of providing up to 80V and 40A of programmable output voltage and current respectively. The power supply does not power on. However, relay noises can be heard inside the instrument during power on.
Teardown of the unit reveals a modular design with PCBs on all sides. The instrument comprises 6 different modules and 3 complete power supplies in parallel. The controller circuit is powered from the middle power supply module. Examination of the boards reveals three separate failed devices.

More details on The Signal Path site.

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

LPCNet – Open Source Neural Net speech synthesis

Posted on Friday, November 30th, 2018 in open source by DP | No Comments

sampling200

Jean-Marc Valin has been working on Neural Network (NN) based speech synthesis in his project called LPCNet:

This new demo presents LPCNet, an architecture that combines signal processing and deep learning to improve the efficiency of neural speech synthesis. Neural speech synthesis models like WaveNet have recently demonstrated impressive speech synthesis quality. Unfortunately, their computational complexity has made them hard to use in real-time, especially on phones. As was the case in the RNNoise project, one solution is to use a combination of deep learning and digital signal processing (DSP) techniques. This demo explains the motivations for LPCNet, shows what it can achieve, and explores its possible applications

Via Rowetel.

#FreePCB via Twitter to 2 random RTs

Posted on Tuesday, November 27th, 2018 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.

LM3886 based stereo amplifier

Posted on Tuesday, November 27th, 2018 in DIY by DP | No Comments

lm3886-based-stereo-power-amplifier

Mark Rehorst blogged about his LM3886 based stereo amplifier build:

Several years ago, National Semiconductor came out with some very high performance, easy to use audio power amplifier ICs.  I was in need of an extra amplifier so I could biamp some of my home-built electrostatic loudspeakers so I tried the LM3886 chip.
This part was chosen because of the ease of use, power output, turn-on and off thump suppression, low distortion, and built-in protection against shorts and thermal runaway.  There isn’t much more to ask of a power amp than that.  When driving electrostatic speakers, you can’t have too much protection!

See the full post on his blog here.

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