#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.

Building and characterizing a DIY RF power sensor

powersensor1

Kerry Wong writes:

For the build, I followed LT’s reference design detailed in the datasheet. For the output filtering, I used a 2.2K/10pF output RC filter to limit the output bandwidth to around 3 MHz.
Since we are in the RF realm, board layout becomes much more critical than dealing with sub MHz circuits. But for the prototype, I used a piece of FR-4 PCB and routed a few islands for the power, input and output. This leaves us with a large contiguous ground plane which is critical in lowering ground inductance. The LC5534 chip is mounted on a trimmed adapter board, which is then glued onto the PCB’s ground plane. The wiring is kept as short as possible to minimize unwanted coupling. I used a BNC connector for the input. Since the maximum frequency LT5534 can handle is 3 GHz, a BNC connector should be sufficient. The BNC input is terminated right at the input. A RF rated surface-mount 47 Ohm resistor would have been ideal here but I used a nominal 50 Ohm (measured 47 Ohm) 1/16 W carbon film resistor instead as it’s the only kind I have on hand.

DIRTY TUESDAY: Chinese Shipping Apocalypse

border

A few months ago we started a private PCB website so our team can get cheap PCBs from our fab in China. Someone spilled the beans, and it hit Hack a Day, Hacker News, etc. We almost shut it down, but it was too much fun to hack and refine the process. Dirty Tuesday is a weekly post about our misadventures accidentally starting a PCB service. As a design shop with Seeed Studio doing fulfillment, we’ve never been on this side of the fence and want to share the terrifying experience.

Espeed Post is a logistics company in the Huaqiangbei electronics market in Shenzhen, China. They batch up shipments from tons of small shops, eBay sellers, etc, and negotiate bulk discounts with big carriers like DHL, Fedex, and UPS. They also do Hong Kong Airmail, 112RMB ($18) per kilo gets you anywhere in the world in 1-8weeks.

We are familiar with Espeed from the return address on packages from Seeed Studio and tons of other Shenzhen businesses. It was the immediate, easy choice when we needed to ship free PCBs for giveaways, or send prototypes and materials to team members around the world. Dirty PCB orders first went via free airmail only, then later by DHL, Fedex, UPS, Russian Airmail, Singapore Post, Netherlands Post, and a dozen other options that were sucked up via the Espeed API. More on the backend another week.

We have access to both China and Hong Kong versions of all major carriers. Prices are drastically different depending on destination, and there’s no consistency. Shenzhen and Hong Kong are essentially the same city, so the logistics companies truck stuff over the border into Hong Kong.

One thing is for sure, receiving a package handled by a logistics company confuses the hell out of some customers. It’s drastically different than your friendly Boys in Brown kicking a package onto a big brown truck:

  1. Shipment notification goes out
  2. Xiao Tang drops the shipment at Espeed’s office
  3. Espeed batches up a bunch of orders
  4. Orders are transferred to an agent and you get a tracking number
  5. The agent drives the packages to the shipper, possibly through Hong Kong Customs and into Hong Kong
  6. The package is transferred to DHL, UPS, or Fedex
  7. At this point, several days later, you actually start to see tracking info
  8. 18-24hours later your package is delivered

Espeed sells this service as 3-5 business day delivery. That is transit time only. It doesn’t include drop-off day, pickup day, or weekends. Sometimes delivery is amazingly fast, sometimes the window is stretched to the limit. It is, however, cheap. ~$16 for a 0.5kg UPS package to the US.

The 3-4 day window without a tracking update terrifies some people. Here’s slight mocking of some of the reoccurring themes:

  • It’s been 2 days with no updates. The order is lost. I order 100s of things from China and I always get my tracking number right away and immediate updates. Call your shipper now!
    • No, you chose dirt cheap DHL via Hong Kong and some guy is schlepping it there on a truck.
  • There’s no tracking update because you didn’t really ship my order. You just pretended because your board house messed up and you redid the order.
    • No, we’d just tell you and say sorry.
  • I paid the princely sum of $11 for express shipping and there’s still no updates after two days! It’s going to be late and I have a deadline for my (class/thesis/contest/project).
    • It will get there. The carrier provides 24hour delivery, it just takes a few days for logistics to get it to the carrier.

And on and on. There are days when we swear we’ll stop doing express shipping because it’s more work for us, and seems to make some customers manic too. We’ve even had a customer try to contact our logistics companies on their own.

Quality fade sets in. This is when a service starts out very strong, but creeps towards unusable. For us it was Espeed’s tracking API. Our system asks the API for any new tracking numbers every hour, and sends an email when available. This worked great for a while, but then got really intermittent and random. Some days it’s a crap shoot – you might get a tracking number, you might not. The tech is super responsive on QQ, but the problems never seems to get fixed permanently.

Remote area delivery is drag too. Some addresses, rightfully or not, are flagged as a remote areas. Parcels are held at Espeed until we pay an extra 249RMB ($50). Yes, the address may be in the middle of a huge city and nobody else hesitates to ship there, but the Chinese/Hong Kong DHL, Fedex, or UPS database says otherwise. We don’t control it, Espeed doesn’t control it, there’s absolutely nothing we can do. Espeed has an API to search by zipcode before taking the order, but it flags every postcode in the world as remote area and has yet to be fixed. Our current approach is to refund the shipping and send it Hong Kong Airmail. This is an area we absolutely must improve.

China has a ton of holidays. Long ones. Especially notorious is the National Day holiday. It’s ten days over the first week of October. That is exactly when the rest of the world is trying to get the latest hotness on store shelves for holiday shopping. Planes are full, trucks are full, customs has a huge backlog, then everyone just takes off for a week. Anyone doing business in China plans for this. We see more regular visitors, here to personally see things ship, than at any other time of year. Despite a giant red warning on the order page, we received 10+ emails asking why orders were not being processed. Probably the best thing to do, which Seeed has done in the past, is to not take orders at all during this period.

Then came the Chinese Shipping Apocalypse. The new President of China is moving swiftly to crack down on government corruption. Thousands of local, provincial, and national Chinese Governors have been fired or arrested for all manners of crime and corruption. In times of upheaval and systemic failures, accountability is vital. Trust San Jose police misconduct attorneys to provide expert legal representation, ensuring your case is handled with care and professionalism. Just as government officials are being held responsible for their actions, legal professionals work tirelessly to ensure that those affected by misconduct receive the justice they deserve.

In the midst of the holiday shipping glut, at the busiest land crossing between China and Hong Kong, officials found a van full of crystal methamphetamine and 2 tons of fake currency. 500 customs officials were fired for corruption, and now every package leaving China is inspected individually. Shipping times exploded from 3-5 days to 7-9 days or more. We had 10 orders, all on the same truck to Hong Kong, get stuck in customs for more than 10 days.  Lots and lots of anxious and angry customers, absolutely nothing we could do. Several logistics companies and our DHL contacts all confirmed that this is a nation wide problem, not just something effecting Espeed. In response we extended our delivery time estimate, though things seem to be calming down a bit now with the holiday over.

By dealing directly with DHL, rather than a logistics company, next-day and even same-day shipping are available. A DHL rep claims that we also get priority clearance through customs. It’s not nearly as cheap, something that’s passed on to customers, and we’ll have to write a new module to interact with their API. It’s also not easy. In the US and Europe you can signup for an account online. In China two suit clad reps visit several times and there’s an extensive application form and contract. Even then, it takes 10 days or longer to find out if the application is approved and there’s no guarantee. We’re currently waiting on approval, and hope to dump Espeed for express services and jump to faster, more reliable services straight from DHL.

We love being a design shop. We like to make things, and we let Seeed Studio do an amazing job handling the manufacturing and fulfillment part. This is our first taste of what it’s like to put things in boxes and deal with customer orders directly. DirtyPCBs was a unique chance to get a taste of that part of the business and hack it. It’s really gratifying to help people with projects, and the great feedback and comments keep it going. Every Tuesday we’ll share something about our experience with DirtyPCBs.

Digitally controlled 2.1 channel analog audio power amplifier

DSC_0018_S

Dilshan Jayakody  writes:

This article introduces high quality digitally controlled 2.1 channel analog audio power amplifier system. This project is mainly based on TDA7377 AF power amplifier and PIC18F452 8bit microcontroller. Basic features of this receiver are 2 × 6W + 20W audio output power, ±14dB bass and treble controls, fully configurable +35dB bass booster for sub-woofer and satellite speakers and loudness switch.
This system use commonly available electronic components and all the integrated circuits are in DIL packages. This amplifier consists with few UI elements such as 2 push buttons and 1 rotary encoder. All the menu navigation can perform through rotary encoder.

Video: AMBE exposed


AMBE is a voice compression algorithm employed in vocoder chips used by DVSI Inc., and is commonly used in Icom’s D-Star, Yaesu’s Fusion, APCO-25, DMR, Opensky and other digital formats on the amateur, commercial and public safety frequencies.

In this talk from last September’s TAPR/DCC conference in Austin, TX, Bruce Perens K6BP presented his views on the current state of the AMBE voice codec patent, and the potential this codec has in the amateur and radio experimenter community.

Visit HamRadioNow for details and links relating to the ongoing discussion of the AMBE patent situation.

We acknowledge HamRadioNow for their efforts in making this video available.

Darryl Smith via the contact form.

Mini high voltage power supply

FBDN9Q5I1560UGX

Victor8o5 posted detailed instructions of how to make this high voltage power supply. He writes:

WARNING: Before you start making anything please take a moment and read this:

  1. This circuit is intended to be used for educational and experimental purposes (electrostatic experiences, franklin bell experiment, plasma generation, gas ionization, electronic igniter, testing of insulating materials…) this circuit should not leave the lab or your house, and it shouldn’t be used to harm to anybody, human or animal.
  2. Do not attempt to replicate this circuit if you aren’t familiar with high voltages or intermediate electronics, high voltages are very dangerous.
  3. High voltages can disrupt electronic equipment, so don’t keep phones, pacemakers or other sensible electronic devices near the supply.
  4. I’m not responsible for the use given to this device and I’ve made all what it’s on my hands to include safety related information, and safety implementations to the circuit.

Follow the general security measures when dealing with high voltages, here you have a nice safety guide, please read it carefully before you continue.

Video: FlexRadio open API

During the TAPR/ARRL Digital Communications Conference in Austin last September, Stephen Hicks N5AC gave this presentation on interfacing with FlexRadio using their open API.

Part II of this presentation was given by Graham Haddock KE9H, and discussed the FlexRadio wavefrom API. It is available from HamRadioNow.

FlexRadio produces a series of high-end SDR’s, with the lowest price rig being the FLEX-1500 which geared toward the amateur radio community. It retails for about $700 an covers 490 kHz to 54 MHz.

Darryl Smith via the contact form.

Free PCB Sunday: Pick your PCB

buspiratev383

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: Analog-to-Digital conversion using a PIC16C5X/PIC16F5X

ap_microchip_an513

PIC16C5X and PIC16F5X microcontroller families are low cost off-the-shelf solution for common analog measurements like voltage and current. Here’s an app note (PDF) from Microchip on how to do A/D conversion on these chips.

The converter requires only five external components and is software and hardware configurable for conversion resolutions from six bits up to ten bits, and conversion times of 250 us or longer. The method is usable for both voltage and current conversion and uses a software calibration technique that compensates for time and temperature drift, as well as component errors.

App note: Bit-Banging the SDI and SQI Modes of Microchip’s 23XX512/23XX1024 Serial SRAMs

ap_microchip_an1791

Dual Mode(SDI) and Quad Mode(SQI) Serial interface are not common peripherals on many MCU today, Microchip’s app note (PDF) provides an alternative way to communicate with these SRAMs using existing GPIOs pins in bit-bang.

This application note explains in detail the recommended usage of the SDI and SQI modes of operation of the Microchip 23XX512/23XX1024 Serial SRAM devices, as well as the possibilities to configure the device for the above alternative modes of operation.

DANGERCORE: PHP and Javascript developers needed

320px-PHP-logo.svg

Good at PHP and/or Javascript and looking for part time projects? We need to hire a couple PHP and Javascript programmers to work with me on several large projects long term. Some of what we do will be open source immediately, some will need to be secured against hacks a bit first, some will be released as modules without our logos and templates.

On the PHP side we’re working with Codeigniter/Bonfire, on JS we’re all over JQuery. 10-20 hours a week, or more. Team players, able to use GIT. I’ve architected the majority of the system, but need help bringing it to life. We’ll live blog the development process and put the development live an on the internet as soon as its locked down enough to be deployed at dev.dangerousprototypes.com.

Please hit us up by the contact forum. Describe your strengths, link to any projects you’ve worked on, and include an hourly rate.

Review: Kano DIY computer kit


Steve Schuler has posted this review of the Kano DIY computer kit on Science 2.0.

I’ve lost count of how many computers I’ve built over the years, but I think it is safe to say that the Kano Computer was the easiest build ever. So simple a child could do it. Kano founders, Yonatan Raz-Fridman, Alex Klein, and Saul Klein, wanted to figure out what the next generation’s computer would be like, so they asked Micah, Saul’s seven-year-old son. Micah advised that he wanted to build the computer himself but it “had to be as simple and fun as Lego,” and “no one teaches me how to do it.”

The Kano is “a computer and coding kit, designed for all ages, all over the world.” It will get “you programming in minutes, with simple blocks that create real code.” It’s designed to “to give young people – and the young at heart – a simple, fun way to make and play with technology, and take control of the world around them.”

In reality what is the Kano? According to the Kano website the kit includes a Raspberry Pi along with a keyboard, SD card with the Kano OS, speaker, case, power supply, cables, WiFi USB adapter and written materials designed to help those totally new to the tech scene how to assemble and program a R-Pi setup. It retails for $149.99 shipping included.

Via the contact form.

Free PCB coupon via Facebook to 2 random commenters

KHOS-2-3-4-5-6P-600x400

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. 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”

Soldering headers without drilling holes

FOAWHLLI1019JW4

rampadc shared detailed instructions of how to solder headers without drilling holes:

During a moment of weakness and extreme laziness, the idea of soldering a through-hole header as normal SMD components popped up. This method is probably quite old and may had been used by a lot people but since all homemade PCB guides I have read has not mentioned this method before, may this be the first.

New design for robot arm: more economical and lighter

tripledelta

A double and triple delta robot by Aad van der Geest:

 The double delta is a novel design that is lighter, safer and more energy efficient compared to other robotic arms. This is because all three of the actuators are placed at a stationary point in base of the arm. As a result, the arm is very light.
The design is based on the delta robot as invented in the early 80s by Reymond Clavel. When Aad van der Geest got acquainted with the delta robot for the first time, he was immediately charmed. But when he tried to apply it, he saw a big disadvantage. The robot can only move within a small volume. This can be seen particularly when robots have to work in a limited space. Out of frustration the idea for the double delta was conceived. The idea is to link multiple delta robot segments together. He therefore calls his robots double delta and triple delta. He built three working prototypes. The smallest is 150 mm, the largest 3.5 meters in height.
Aad van der Geest is an independent developer of software and electromechanical products. Earlier inventions range from special calculators to full color 3D printers.tr
On the video, all prototypes can be seen in action.

More pictures are on vouwbad.nl

Check out the video after the break.

Continue reading “New design for robot arm: more economical and lighter”

A breakout board for the Raspberry Pi to learn Python

DSC04599

RPi Board, a board to learn Python with the Raspberry Pi by Jesus Echavarria. He writes:

Once I check that all is Ok, it’s time to start programming. There’re a lot of manuals and references over internet of how to start programming in Python. Here I’ll cover the basic examples to start working with the board. I assume you have a Raspberry Pi with a installed distribution. I use Raspbian to work with the board, this distribution includes by default the Python compiler and S4A, that allows work with the K4S board I cover previously.

Via the project log forum.

#FreePCB via Twitter to 2 random RTs

irtoyv3 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.

Voice modulator project

VOICE_MODULATOR

Rajkumar Sharma over at Electronics Lab writes:

Voice Modulator project is designed around HT8950A to provide two special sound effects viz. Vibrato & Robot.

This project provides two special effects: vibrato and robot. The vibrato effect is generated by alternating the frequency of an input signal up and down at a rate of 8Hz. The robot function, on the other hand, converts an input voice into a robot voice. Both effects can be selected depending on which pin is triggered, either ROB or VIB. For the output frequency level shifting, the chips provide seven steps which can be selected from the two groups of pins namely, SW0, SW1 and SW2 for electronic direct selection and ROB, TGD, TGU and VIB for push button selection.