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Free PCB Sunday: Pick your PCB

Posted on Sunday, February 26th, 2017 in Free PCBs by DP | 28 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: HT45F3420 LED flashlight application

Posted on Sunday, February 26th, 2017 in app notes by DP | No Comments

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Holtek’s HT45F3420 MCU provide LED flashlight application all in with minimal external components. Link here (PDF)

In traditional LED flashlight application circuits, the battery is used to directly drive the LED which will cause uneven brightness levels and the possibility of damaged LEDs due to changing battery conditions. Using the HT45F3420 for LED flash application, both buck and constant current techniques are used.

App note: BH45F0031 Earphone jack communication

Posted on Sunday, February 26th, 2017 in app notes by DP | No Comments

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Holtek’s App note about their audio to digital signal converter chip BH45F0031 that together with an phone app, communication via audio phone jack is possible. Link here (PDF)

The BH45F0031 is a Flash type 8-bit high performance RISC architecture microcontroller, which is designed for smart phone headset interface applications that can directly transmit data and communicate with the microcontroller using their audio earphone interface.

The BH45F0031 can convert the analog audio signals from mobile phones into digital data and transmit them to a master external MCU. The device can also convert the digital data from the master MCU into analog audio signals and transmit them to mobile phones.

Free PCB coupon via Facebook to 2 random commenters

Posted on Friday, February 24th, 2017 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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Ultrasonic Transducers – measurements and horn design

Posted on Thursday, February 23rd, 2017 in how-to by DP | No Comments

Lindsay Wilson writes:

Over the past few years, I keep getting inquiries from people asking about how to measure the resonant frequency of these transducers, how to design horns, tune the length etc. I decided it was time to do a video about the entire process – hopefully I’ve covered everything relevant. If you check the YouTube description, I’ve put time links to each individual section of the video.

Project info at imajeenyus.com.

Teardown and analysis of microwave (26.5GHz) electro-mechanical step attenuators

Posted on Tuesday, February 21st, 2017 in Teardowns by DP | No Comments

Teardown and analysis of microwave (26.5GHz) electro-mechanical step attenuators from The Signal Path:

In this short episode Shahriar takes a close look at a pair of Hewlett Packard microwave electro-mechanical step attenuators operating up to 26.5GHz. Mechanical attenuators offer excellent repeatability, low insertion loss and nearly limitless linearity. The teardown reveals that the construction of both modules is very similar on the microwave path. In fact, the lower-frequency model still uses the same attenuator components. The newer model employs electronic control circuity while the older generation attenuator uses purely mechanically controlled DC path. Both models use a solenoid style actuators for step attenuation control.

DIY laser scanning microscope

Posted on Monday, February 20th, 2017 in Arduino, DIY by DP | No Comments

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Venkes shared detailed instructions of how to make a DIY Laser Scanning Microscope (LSM):

The reason I was thinking of a DVD pick-up is that it houses a laser and a lens capable of projecting a spot of visible laser light small enough to “see” a bit on a DVD. And those bits are very small (320nm)! Furthermore it houses coils to steere the lens (sideways and up and down) and a detection part. This steering is necessary to be able of following the microscopic narrow tracks on a CD or DVD while spinning (sideways moving of the lens) and follow height differences while spinning (up and douwn movement of the lens). You can imagine that folowing the track must be very precise considdering the turning speed and the bit size! These characteristics are exactly what we need!

Project instructables here.

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

BlackMagicProbe SMDprutser style

Posted on Monday, February 20th, 2017 in ARM by DP | 3 Comments

BlackMagicProbe

Sjaak has published a new build:

When you get started on ARM microcontrollers things are very overwhelming at first… After coping with the first few hurdles like installing a toolchain and IDE, the next part should be getting a tool to program the chip. Many vendors have some kind of bootloader burned in the chip, which can’t be altered. Some manufacturers use serial, some use USB (mass-storage, DFU or HID). Unfortunately every vendor has it own implementation and they aren’t compatible with each other and may require special hardware. This can make it hard(er) for you to change between vendors. Another downside is your code can only be debugged by ‘printf” and not ‘realtime’.

More details at smdprutser.nl.

 

Free PCB Sunday: Pick your PCB

Posted on Sunday, February 19th, 2017 in Free PCBs by DP | 26 Comments

BP-600x373

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: Charging batteries using USB power

Posted on Sunday, February 19th, 2017 in app notes by DP | No Comments

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Fairly old application note from MAXIM Integrated about getting out power from USB ports. Link here (PDF)

Many devices with rechargeable batteries use USB power to recharge the batteries while they are connected. This application note describes the power available from USB and how it can be used to charge batteries, including circuits and some hints.

App note: Improve flicker performance of direct AC driven LED fixtures with self valley fill

Posted on Sunday, February 19th, 2017 in app notes by DP | No Comments

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Application note from ON Semiconductors on LED lighting flicker caused by its own AC supply by adding an improved self valley fill circuit. Link here (PDF)

To provide power to LED loads from AC input, SwitchMode Power Supplies (SMPS) are generally used since LED need to be driven by regulated current. Consequently, LED lighting solution have to inherit the design complexity of a typical SMPS which includes designing the magnetic component, handling of Electromagnetic Interferences (EMI) as well as implementing Power Factor Correction (PFC). Direct-AC Drivers (DACD) for LEDs provides a new way to drive the LED load from an AC input with much simpler system architecture while satisfying EMI and power factor (PF) requirements with minimal effort. However, its drawback is flickering of light output at the zero crossing of AC line voltage due to loss of current to the LED load.

Though flicker is not always obvious, it can still cause headaches for a small percentage of people exposed to flickering lights for long periods. This is a major issue for offices, schools, stores and other brightly lit commercial and industrial spaces where people spend a lot of time.

Programming an 8 digit 7-segment display, the easy way, using a Max7219

Posted on Friday, February 17th, 2017 in how-to, Interface, LEDs by DP | 5 Comments

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Allan Schwartz shows off the easy way to interface 7-segment displays using the MAX7219:

Previously, in part 1 of my blog posting Programming a 7-segment Display, using just Arduino digital pins (the hard way) we had demonstrated how to hook up a pair of 7-segment displays to an Arduino, treating each individual segment as a separate LED. There was a bit of tricky logic to translate each digit into the segments A, B, C, D, E, F, G plus additional logic to turn the digital pins on or off. Although I tried to code it as efficiently as possible, the logic may have been difficult to understand.
Also, constructing the project was fairly tedious, with dozens of resistors and hook-up wires.
Instead, lets do this the easy way. A typical MAX7219 module comprised of a single MAX7219 chip and eight 7-segment displays.

More details at www.whatimade.today.

Cheap plant watering sensor

Posted on Friday, February 17th, 2017 in tutorials by DP | No Comments

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A detailed instructions of how to design a cheap plant watering sensor from LuckyResistor:

I have a couple of plants in flowerpots and this plants not only like some light, they also need water from time to time. Watering this plants is something I often forget, with sad results. There are ready made solutions for this, but I have some objections with all of them. To be clear: There are really smart products out there – it is absolutely nothing wrong with them. It is just as I like to build my own fan controller, I like to build my own plant watering sensor in my very own fashion.

More info at Luckyresistor.me.

Free PCB coupon via Facebook to 2 random commenters

Posted on Friday, February 17th, 2017 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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Tiva and Stellaris Launchpad RTC usage in Energia

Posted on Thursday, February 16th, 2017 in tutorials by DP | No Comments

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Vadim has posted a tutorial on how to use internal RTC of Stellaris and Tiva Launchpad boards in Energia IDE:

For those of you who still have one of those old Stellaris Launchpads, I’m going to show how to utilize one of its most useful features – real time clock – in a simple way. Actually, the Hibernation module is the same in the new Tiva Launchpad, so it’s supposed to work there as well.

More info at Vadim Panov’s blog.

Via the contact form.

Logging I2C Data with Bus Pirate and Python

Posted on Thursday, February 16th, 2017 in Bus Pirate by DP | No Comments

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Scott Harden writes, “I’m working on a project which requires I measure temperature via a computer, and I accomplished this with minimal complexity using a Bus Pirate and LM75A I2C temperature sensor.”

More details at SWHarden.com.

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

#FreePCB via Twitter to 2 random RTs

Posted on Tuesday, February 14th, 2017 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.

MeArm Pi – Build your own Raspberry Pi powered robot arm!

Posted on Tuesday, February 14th, 2017 in open source, R-Pi, robotics by DP | 2 Comments

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Here’s an interesting open source project on Kickstarter the world’s first robot arm kit for the Raspberry Pi, the MeArm Pi:

We believe in helping people understand how the world works. With so much development going on in robotics at the moment, now is the perfect time to get to know what it takes to build your own robot. The MeArm Pi is an award winning robotic arm kit that’s simple enough for a child to assemble. It integrates directly with the Raspberry Pi you know and love and you can either control it directly using the on-board joysticks or by programming it from the Pi in your favourite programming language.

Take control of the world around you.

You can visit the project’s Kickstart page and their website Mime Industries for more info.

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

A Line-us clone

Posted on Monday, February 13th, 2017 in DIY by DP | No Comments

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Barton Dring has a nice build log on his Line-us clone project:

I have been going to the monthly Amp Hour, Hardware Happy Hour meetup.  A lot of people bring something to show.  My projects are too big.  Also, you need to bring your own power.  The meetup standard seems to be running off a USB cord. I was brainstorming ideas, when I saw the Line-us project on Kickstarter. It looked like the perfect size and power. I also love the challenge of non linear kinematics.

More details at Buildlog.Net blog.

App note: Using touch interface in harsh environments

Posted on Sunday, February 12th, 2017 in app notes by DP | No Comments

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Tough design and software reference from NXP of touch interface. Link here (PDF)

The touch-sensing method is used to replace most of traditional tact switch inputs as a new type of human-machine interface used in home-appliance applications. However, using such kind of detection method in harsh environment is still a challenge for most of product designers. A good balance of fast response and no false trigger in key detection is always an essential factor for the user-interface design. The touch-sensing input (TSI) module in Freescale MCUs provides capacitive touch detection with high sensitivity and durability, which can help customers to adapt this kind of human touch-sensing technology quicker.

This application note describes how to use the S08PT family MCU features in applications with emphasis on both touch-sensing interface and safety aspect. Different techniques in circuit design, intelligent software control and reliable mechanical structure are illustrated in this application note to show how to achieve a product design with protection features for handling faults and fast TSI response without any false trigger in extreme conditions. Most of the critical scenarios and unexpected use cases from the end-user point of view must be fully studied and well-covered in advance to prevent any serious flaw persisting in the final design stage which causes significant delay in the whole project schedule.

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