Sometimes tearing down a cheap appliance is more interesting that tearing down an expensive one. A lot of the best engineering happens when cost is an issue. You may not solve the problem well, but you can solve it well enough for a discount shelf.
[openschemes] purchased a 1.8kW induction hot plate at a low price off Amazon. The reasons for the discount soon became apparent. The worst of which was a fully intolerable amount of high frequency switching noise. Wanting to know how it worked, he took it apart.
After he had it apart on his desk, he deciphered the circuit, and wrote about it clearly. As usual with extremely cheap electronics, some clever hacks were employed. The single micro-controller was used for monitoring, and generated a PWM signal that was instantly converted to DC through some filters. All the switching was done the old fashioned way, which explained why the hotplate seemed so brainless to [openschemes] when he first turned it on.
Lastly, he did some work on manually controlling the cooktop for whatever reason. The good news? He managed to figure out how to control it. Unfortunately he also destroyed his unit in the process, via a misapplication of 1200 volts. A fitting end, and we learned a lot!
Thanks [David Balfour] for the tip!
We love a good tear-down, and last week’s “Enginursday” at Sparkfun satisfied our desire to see the insides of AC-DC switching power supplies, accompanied by knowledgeable commentary. [MTaylor] walks us through how the basic circuit works and then points out why various other elaborations are made, and how corners are sometimes cut, in a few power supplies that he’s taken apart.
What struck us in the comparison was that some of the power supplies were very minimal designs, while others had “features” that were obviously added after the fact. For instance, the Li Shin supply (about half-way down the page) has an extra circuit board tacked on to the bottom of the real circuit board to act as EM shielding.
Rather than declare this a dodgy hack, as we would have, [MTaylor] declares it to be “Good News!” because it means that they’ve probably run an emissions test, failed it, and then added this bit on to make it pass. This is of course in contrast to the other makers who’ve probably never even considered emissions testing. Sigh.
If you’re interested in seeing more inner bits of power bricks, Sparkfun forum reader [sgrace] passed along this field guide to various power supplies, which is also worth a look. And if you’re interested in building yourself the ultimate bench power supply, look no further than this Hackaday.io project by [The Big One].
[Brian Dipert] over at EDN has a teardown of Belkin’s answer to the Internet of Things (IoT) craze: the WeMo. This little WiFi gadget plugs into an outlet and lets you turn a connected device on and off from a smart phone app or something like Amazon Echo.
As you might expect from a cheap piece of consumer hardware, there’s not a whole lot inside. The digital board contains a Ralink WiFi chip, an antenna etched on the PCB, and a handful of components, including an SDRAM and some flash memory.
Continue reading “Belkin WeMo Teardown”
Until the 1960s, watches and clocks of all kinds kept track of time with mechanical devices. Springs, pendulums, gears, oils, and a whole host of other components had to work together to keep accurate time. The invention of the crystal oscillator changed all of that, making watches and clocks not only cheaper, but (in general) far more accurate. It’s not quite as easy to see them in action, however, unless you’re [noq2] and you have a set of strobe lights.
[noq2] used a Rigol DG4062 function generator and a Cree power LED as a high-frequency strobe light to “slow down” the crystal oscillators from two watches. The first one he filmed was an Accutron “tuning fork” movement and the second one is a generic 32,768 Hz quartz resonator which is used in a large amount of watches. After removing the casings and powering the resonators up, [noq2] tuned in his strobe light setup to be able to film the vibrations of the oscillators.
It’s pretty interesting to see this in action. Usually a timekeeping element like this, whether in a watch or a RTC, is a “black box” of sorts that is easily taken for granted. Especially since these devices revolutionized the watchmaking industry (and a few other industries as well), it’s well worthwhile to take a look inside and see how they work. They’re used in more than just watches, too. Want to go down the rabbit hole on this topic? Check out the History of Oscillators. Continue reading “Strobe Light Slows Down Time”
LEDs are amazing things. As time marches on, they are being used in more and more lighting applications – everything from household bulbs to automotive headlights. But the push for smaller, cheaper, and brighter LEDs seems to have hit a snag for some of the less reputable manufactures.
Case in point, [bigclivedotcom] has been testing of some 100 Watt LEDs from eBay. When these LEDs work correctly, they put out a face-melting beam of light that you wouldn’t dare looking into (picture the scene from Raiders of the Lost Ark). They also have some unusual specs for an LED, like running on 30 Volts – and that’s a lot compared to the forward voltage of most LEDs at around 2.5 volts@20 mA.
So what gives? Well many of these high-wattage LEDs use a string of several LEDs in series. And as [bigclivedotcom] points out, this can be a real problem when a few of the LEDs begin to fail and act more like a low value resistor than a typical LED. In the videos after the break you can see [bigclivedotcom] test the LEDs to get a better look and what’s happening and why.
Continue reading “Why 100 Watt eBay LEDs Are Not Your Friends”
Microcontrollers existed before the Arduino, and a device that anyone could program and blink an LED existed before the first Maker Faire. This might come as a surprise to some, but for others PICs and 68HC11s will remain as the first popular microcontrollers, found in everything from toys to microwave ovens.
Arduino can’t even claim its prominence as the first user-friendly microcontroller development board. This title goes to the humble Basic Stamp, a four-component board that was introduced in the early 1990s. I recently managed to get my hands on an original Basic Stamp kit. This is the teardown and introduction to the first user friendly microcontroller development boards. Consider it a walk down memory lane, showing us how far the hobbyist electronics market has come in the past twenty year, and also an insight in how far we have left to go.
Continue reading “Before Arduino There was Basic Stamp: A Classic Teardown”
We remember when buying even a modest digital multimeter was a big investment. These days, you can find tool stores giving away cheap meters and if you are willing to spend even a little money, you can buy a meter with tons of features like capacitance, temperature, and other measurements.
Like most things, though, you can pay a little money for a bargain, or you can overpay for a dud. To help you pick, [TechnologyCatalyst] decided to do an extensive video review of 15 different meters in the under $50 price category.
If you are looking for a quick video to watch, you might want to move along. The review is in nine videos ranging from an introduction, to a comparison of build quality, discussion about the displays on each meter, and, of course, the measurement capability of each meter. There’s even a video that shows tear downs so you can see inside the instruments.
Continue reading “$50 Multimeter Comparison and Teardown”