$3 Multimeter Teardown

[Diode Gone Wild] and his cat decided to see how a $3 meter worked inside. The meter was marked as a DT-830B and he already had an older one of the same model, and he wondered how they could afford to sell it — including shipping — for $3. You can see a video of his testing, teardown, and reverse engineering below.

What was odd is that despite having the same model number, the size of the meter was a bit different. When he opened the case to install a battery, he noticed the board didn’t look like it had fuses or components appropriate for the rated voltages. He decided the missing parts might be under the board and tested the meter.

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US Announces Withdraw From Postal Treaty; International Shipping Prices Expected To Rise

The United States has announced plans to withdraw from a 144-year postal treaty that sets lower international shipping rates. The US claims this treaty gives countries like China and Singapore an unfair advantage that floods the US market with cheap packages. The BBC reports the withdraw of this treaty will increase shipping costs from China by between 40% and 70%.

The treaty in question is the Universal Postal Union, which established that each country should retain all money it has collected for international postage. The US Chamber of Commerce has said this treaty, ‘leads to the United States essentially paying for Chinese shipping’. This is especially true since 2010, when the US Postal Service entered an agreement with eBay Greater China & Southeast Asia and the China Post Express & Logistics Corporation. This agreement established e-packet delivery where packages weighing up to 2 kg would be delivered at lower prices. If you have ordered inexpensive products shipped from abroad, it is likely the e-packet price that made this possible.

This will affect businesses that capitalize on imports and exports; the storefronts on Amazon and eBay that resell Chinese goods rely on cheap shipping from China. It will also affect companies based outside of the United States that ship to US customers. Small businesses within the US who manufacture at low enough quantities to get their components/raw-materials shipped under the e-packet rates will also see a hit. An increase in shipping costs will mean higher prices for all of these products.

The move is also being justified as a way to even the playing field for US manufacturers who are shipping from within the US and may be paying higher rates to ship to the same customers as foreign-bought goods. It is the latest development in a growing trade war between the US and China which has already seen several rounds of tarrifs on goods like electronics, and even 3D printing filament. It’s hard to see how the compounding effect of these will be anything but higher prices for consumers. Manufacturers seeing the pinch on raw materials and components will pass this on to customers who will also soon see higher shipping prices than they are used to.

Hams See Dark Side Of The Moon Without Pink Floyd

Ham radio operators bouncing signals off the moon have become old hat. But a ham radio transmitter on the Chinese Longjiang-2 satellite is orbiting the moon and has sent back pictures of the Earth and the dark side of the moon. The transceiver’s main purpose is to allow hams to downlink telemetry and relay messages via lunar orbit.

While the photo was received by the Dwingeloo radio telescope, reports are that other hams also picked up the signal. The entire affair has drawn in hams around the world. Some of the communications use a modulation scheme devised by [Joe Taylor, K1JT] who also happens to be a recipient of a Nobel prize for his work with pulsars. The Dwingeloo telescope has several ham radio operators including [PA3FXB] and [PE1CHQ].

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Laser Noob: Getting Started With The K40 Laser

Why spend thousands on a laser cutter/engraver when you can spend as little as $350 shipped to your door? Sure it’s not as nice as those fancy domestic machines, but the plucky K40 is the little laser that can. Just head on down to Al’s Laser Emporium and pick one up.  Yes, it sounds like a used car dealership ad, but how far is it from the truth? Read on to find out!

Laser cutting and engraving machines have been around for decades. Much like 3D printers, they were originally impossibly expensive for someone working at home. The closest you could get to a hobbyist laser was Epilog laser, which would still cost somewhere between $10,000 and $20,000 for a small laser system. A few companies made a go with the Epilog and did quite well – notably Adafruit used to offer laptop laser engraving services.

Over the last decade or so things have changed. China got involved, and suddenly there were cheap lasers on the market. Currently, there are several low-cost laser models available in various power levels. The most popular is the smallest – a 40-watt model, dubbed the K40. There are numerous manufacturers and there have been many versions over the years. They all look about the same though: A blue sheet metal box with the laser tube mounted along the back. The cutting compartment is on the left and the electronics are on the right. Earlier versions came with Moshidraw software and a parallel interface.

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Using An FPGA To Navigate China’s Railroads

If you’re headed over to mainland China as a tourist, it’s possible to get to most of the country by rail. China is huge though, about the same size as the United States and more than twice the size of the European Union. Traveling that much area isn’t particularly easy. There are over 300 train terminals in China, and finding the quickest route somewhere is not obvious at all. This is an engineering challenge waiting to be solve, and luckily some of the students at Cornell Engineering have taken a stab at efficiently navigating China’s rail system using an FPGA.

The FPGA runs an algorithm for finding the shortest route between two points, called Dijkstra’s algorithm. With so many nodes this can get cumbersome for a computer to calculate, but the parallel processing of a dedicated FPGA speeds up the process significantly. The FPGA also includes something called a “hard processor system“, or HPS. This is not a soft-core, but dedicated computing hardware in the form of an ARM Cortex-A9. Testing showed that utilizing both the HPS and the FPGA can speed up the computation by up to ten times over a microcontroller alone.

This project goes into extreme detail on the methodology and the background of the math and coding involved, and is definitely worth a read if you’re interested in FPGAs or traveling salesman-esque problems. FPGAs aren’t the only dedicated hardware you can use to solve these kinds of problems though, if you have a big enough backpack while you’re traveling around China you could also use a different kind of computer.

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Load Bank Teardowns Show Danger

[Syonyk] has been acquiring some large load banks to test power supplies and battery packs. These devices consist of a big current sink, a measurement device, and a fan. He picked up two similar-looking boards from the usual Chinese sources, both rated for 150W, both for about $30. Upon closer examination, though, he found that one was really a bargain and the other was likely to blow up.

The loads are rated for 60V and as you can see from the photos, appear virtually identical at a glance. They offer a configurable cut-off voltage and even use 4-wire measurement to avoid problems with voltage drop through the power cables.

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Bunnie Weighs In On Tariffs

[Bunnie] has penned his thoughts on the new 25% tariffs coming to many goods shipped from China to the US. Living and working both in the US and China, [Bunnie] has a unique view of manufacturing and trade between the two countries. The creator of Novena and Chumby, he’s also written the definitive guide on Shenzen electronics.

All the marked items are included in the new tariffs

The new US tariffs come into effect on July 6th. We covered the issue last week, but Bunnie has gone in-depth and really illustrates how these taxes will have a terrible impact on the maker community. Components like LEDs, resistors, capacitors, and PCBs will be taxed at the new higher rate. On the flip side, Tariffs on many finished consumer goods such as cell phone will remain unchanged.

As [Bunnie] illustrates, this hurts small companies buying components. Startups buying subassemblies from China will be hit as well. Educators buying parts kits for their classes also face the tax hike. Who won’t be impacted? Companies building finished goods. If the last screw of your device is installed in China, there is no tax. If it is installed in the USA, then you’ll pay 25% more on your Bill of Materials (BOM). This incentivizes moving assembly offshore.

What will be the end result of all these changes? [Bunnie] takes a note from Brazil’s history with a look at a PC ISA network card. With DIP chips and all through-hole discrete components, it looks like a typical 80’s design. As it turns out the card was made in 1992. Brazil had similar protectionist tariffs on high-tech goods back in the 1980’s. As a result, they lagged behind the rest of the world in technology. [Bunnie] hopes these new tariffs don’t cause the same thing to happen to America.

[Thanks to [Robert] and [Christian] for sending this in]