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DIY USB power bank from laptop battery

Posted on Tuesday, August 23rd, 2016 in DIY, hacks by DP | No Comments

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DIY USB power bank made from an old laptop battery from DoItYourselfGadgets:

A situation many can relate to: an empty smartphone battery and no outlet around! That’s exactly why I recycled an old laptop battery into an USB power bank.
This article will show you the basic powerbank circuit consisting of Lithium cell charging circuit, boost converter and toggle switch as well as my improved version with self activating boost converter and LED status indicator and homemade housing.

More details at DoItYourselfGadgets project page.

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

#FreePCB via Twitter to 2 random RTs

Posted on Tuesday, August 23rd, 2016 in Free PCBs by DP | No Comments

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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.

Breadboard line driver module

Posted on Tuesday, August 23rd, 2016 in DIY, RF by DP | No Comments

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Scott from SWHarden has published a new build:

Line driver chips are one of my go-tos for quickly amplifying digital signals because they’re so fast to drop in a breadboard and they provide a strong output with very high impedance inputs and need no external components. Individual buffer of the integrated chip can be paralleled to multiply their current handling capabilities too. One of the common variants is the 74HC240.

More details at SWHarden homepage.

Free PCB Sunday: Pick your PCB

Posted on Sunday, August 21st, 2016 in Free PCBs by DP | 35 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: Measuring a loudspeaker impedance profile using the AD5933

Posted on Sunday, August 21st, 2016 in app notes by DP | No Comments

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An application note from Analog Devices about AD5933, this provides a low cost substitute to expensive test equipment like signal generators, oscilloscope and voltmeters in getting the speaker’s impedance profile. Link here (PDF)

This application note describes a circuit architecture using the AD5933 that allows the system designer to measure the impedance profile of the loudspeaker and integrate this circuitry into the audio signal chain. This offers many benefits. Upon system power-up, for example, the circuitry provides the ability to measure the impedance profile and thus the acoustic properties of the loudspeaker, enabling direct comparison to a factory calibrated profile stored nearby. Any changes in the impedance profile are detected and further diagnostics are carried out, preventing premature damage.

App note: Choosing the appropriate component from data sheet ratings & characteristics.

Posted on Sunday, August 21st, 2016 in app notes by DP | No Comments

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Chossing the right power semiconductor for an application, a technical note from IXYS. Link here

This application note is intended to show how to choose the appropriate rating of a power semiconductor component for a known application using the specifications given in the datasheet. The explanations have been kept sufficiently general to be applicable to all common power circuits. However, for the sake of concreteness, they focus on IXYS IGBT modules and discretes respectively with or without diode. Proceeding as described in the following enables the designer to gain all necessary information from the data sheets for the most economic selection of power semiconductors.

App note: Designing for board level electromagnetic compatibility

Posted on Saturday, August 20th, 2016 in app notes by DP | No Comments

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Designing for board level electromagnetic compatibility application note (PDF!) from NXP:

Electromagnetic interference (EMI) is a major problem in modern electronic circuits. To overcome the interference, the designer has to either remove the source of the interference, or protect the circuit being affected. The ultimate goal is to have the circuit board operating as intended — to achieve electromagnetic compatibility (EMC).
Achieving board level EMC may not be enough. Although the circuit may be working at the board level, but it may be radiating noise to other parts of the system, causing problems at the system level.
Furthermore, EMC at the system or equipment level may have to satisfy certain emission standards, so that the equipment does not affect other equipment or appliances.
Many developed countries have strict EMC standards on electrical equipment and appliances; to meet these, the designer will have to think about EMI suppression — starting from the board level.

Outmoded Sequencer project

Posted on Saturday, August 20th, 2016 in DIY by DP | No Comments

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LuckyResistor made a miniature music machine -the outmoded sequencer project and wrote a post on his blog detailing its assembly:

I just started an interesting new project: The Outmoded Sequencer Project. It is an minimalistic music machine. You can use a 8×8 “programming” matrix to create simple melodies which are looping endlessly. This melody can be changed while the device is playing it. Here a short demonstration

My goals for the project were:

  • No microcontroller
  • Only outmoded, basic and cheap components
  • As minimalistic as possible
  • Maximize the fun with these limitations

Project info at Lucky Resistor’s blog.

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

Free PCB coupon via Facebook to 2 random commenters

Posted on Friday, August 19th, 2016 in Free PCBs by DP | 1 Comment

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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:

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RC boat with NRF24L01+ and Arduino

Posted on Friday, August 19th, 2016 in Arduino, project logs by DP | No Comments

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Markus Gritsch writes:

I and my little son built a small electric boat from a kit. However, the kit only offered turning on the motor with a switch, and let the boat cruise wherever fortune it may take.
I thought why not improve it a bit by adding some RC capability. I had some left over toy quad copter remote controls, and decided to use them by building the receiver side out of an 3 $ Arduino mini knock off and the popular NRF24L01+ chip.

Via the project log forum.

Check out the video after the break.

(more…)

PowerShell is open sourced and is available on Linux

Posted on Friday, August 19th, 2016 in open source by DP | 1 Comment

Microsoft is announcing PowerShell on Linux and open source, that is available on GitHub:

Today, we are taking the next step in our journey. I am extremely excited to share that PowerShell is open sourced and available on Linux. (For those of you who need a refresher, PowerShell is a task-based command-line shell and scripting language built on the .NET Framework to help IT professionals control and automate the administration of the Windows, and now Linux, operating systems and the applications that run on them.) I’m going to share a bit more about our journey getting here, and will tell you how Microsoft Operations Management Suite can enhance the PowerShell experience.

More details at Microsoft Azure blog.

Biking sweeper detectors

Posted on Thursday, August 18th, 2016 in how-to by DP | No Comments

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Sweeper bike detectors project from Cliff Batson (N4CCB):

They are equipped with a Moteino transmitter running on 9V battery power that keeps them going all day for the event, while transmitting a beacon every 4s. They beacon their identity to the various checkpoints/rest points and in sag vehicles (cars with “bike detector” receiver units) to keep track of which bikes are near by.

Via LowPowerLab.

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

Bi-directional voltage level translator – Board house test

Posted on Wednesday, August 17th, 2016 in DirtyPCBs.com, PCBs by DP | No Comments

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Lukas Fassler from Soldernerd shares his experience with DirtyPCBs:

I can think of a lot of situations where it could be useful. But the main reason for this project was to gain some experience with getting a PCB professionally manufactured by a board house. For several years I have done my own designs but I always milled and drilled them myself. This had pros and cons. I never had to worry about silk screens or solder masks because my boards never had any. On the other hand I suffered from the lack of plated-through holes. Vias were always a pain in the arse because I had to manually solder in pieces of wire to connect the two sides. And it was very difficult if not impossible to put a via below a component which made the layout challenging when working with ICs with many and/or tightly spaced pins.

More details at Soldernerd homepage.

#FreePCB via Twitter to 2 random RTs

Posted on Tuesday, August 16th, 2016 in Free PCBs by DP | 1 Comment

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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.

Dekatron tubes controlled by Arduino

Posted on Tuesday, August 16th, 2016 in Arduino, DIY by DP | No Comments

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Flathagen writes:

Interfacing dekatron tubes with a microcontroller is fairly easy, once you understand how the tubes work. Threeneuron’s Pile o’Poo of Obsolete Crap provides the necessary background information and schematics for making this work.
I used two russian OG-4 tubes. I prefer the orange look of the neon tubes rather than the purple look of the argon filled OG-3 tubes. The latter tubes just look to modern for my liking. On the above picture you can see how I have mounted the tubes on a rig alongside two Magic eye tubes.

More details at DIYcrap blog.

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

Light following bristle bot

Posted on Tuesday, August 16th, 2016 in DIY by DP | No Comments

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Facelesstech made a light following bristle bot and wrote a post on his blog detailing its assembly:

There is one thing missing from all my projects so far…..Something that moves. Bristle bots are very similar to hex bugs but are built from toothbrush heads and pager motors. I thought the idea of bristle bots was cool but they were no brains to them until i seen this blog post where you could control one with a light. Essentially this light following bristle bot is just two bristle bots side by side so it would be steered.

More info at Facelesstech’s blog.  Project files available on github.

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

25 watt hybrid EL84 tube amp

Posted on Monday, August 15th, 2016 in DIY by DP | No Comments

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Ray Ring from Circuit Salad has published a new build, 25 watt hybrid EL84 tube amp:

This is my new  hybrid guitar tube amp which utilizes a solid-state input stage, DSP reverb, and solid-state phase splitter. Only the push pull, class AB output stage utilizes tubes, namely two EL84’s run at 390 volts with cathode bias. The bias uses two 15 volt zeners which creates a bias current of about 26mA. This requires almost 30 volts of swing on the grids to drive the amp to saturation. This is accomplished with a little switch mode boost converter that generates 29 volts to drive the phase splitter opamps. All of the solid-state circuitry runs off the AC filament supply for the tubes. The solid state portion is basically my stomp amp design( also on this blog) minus the final power amp, which is replaced with the phase splitter.

More details at Circuit Salad’s homepage.

Free PCB Sunday: Pick your PCB

Posted on Sunday, August 14th, 2016 in Free PCBs by DP | 29 Comments

IRToy

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:

(more…)

App note: Voltage to current conversion

Posted on Sunday, August 14th, 2016 in app notes by DP | No Comments

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Using Apex Microtechnology’s power op amps for voltage controlled current sources (VCCS’s) application note, Link here (PDF)

Voltage controlled current sources (or VCCS’s) can be useful for applications such as active loads for use in component testing or torque control for motors. Torque control is simplified since torque is a direct function of current in a motor. Current drive in servo loops reduces the phase lag due to motor inductance and simplifies stabilizing of the loop.

App note: Programmable power supplies

Posted on Sunday, August 14th, 2016 in app notes by DP | No Comments

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Apex Microtechnology’s application note about programmable power supplies. Link here (PDF)

The programmable power supply (PPS) is not only a key element in automated test equipment, but it is also used in fields as diverse as industrial controls, scientific research and vehicular controls. When coupled to a computer, it bridges the gap from the software to the control task at hand. This application note examines the basic operation of the PPS, the multitude of possible configurations and the key accuracy considerations.

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