I have made many electronic loads in the past. For instance this simple harddrive cooler housed small dummy load, this more sophisticated constant current/constant programmable load and this heavy-duty electronic load that is capable of sinking over 1kW under peak load. In this blog post though, I am going to take a look inside an Array 3711A DC electronic load I recently purchased on eBay. You can find a video of this teardown towards the end of the post.
Typically, a lab power supply can only operate within a single quadrant. Take a positive voltage power supply for example, it can only output or source current. If any attempt is made trying to sink current into the power supply by connecting a voltage source with a higher voltage than the output voltage of the power supply, the power supply would lose regulation since it cannot sink any current and thus is unable to bring down and regulate the voltage at its output terminals.
The Agilent 66312A dynamic measurement DC source however is a two-quadrant power supply, it not only can source up to 2A of current between 0 and 20V, but also can sink up to 1.2A or 60% of its rated output current as well. Although lacking some key functionality of a source measure unit (SMU), Agilent 66312A can nevertheless be used in similar situations where both current sourcing and sinking capabilities are needed.
Before the advent of optical mice, the go to technology was a steel ball which moved two drive shafts to indicate position.
A good example of this is this Microsoft “Intellimouse”.
As expected the electronics are built around a small micro controller
My original plan was to find a replacement LCD and restore the unit to its original full functionality. But the LCD used in this unit is likely specifically made for the 169X series of power supplies and through some initial research I realized it would be extremely difficult to get hold of unless I could find a donor unit with a functional LCD inside. After I received the power supply, I realized that it had more issues than just the broken LCD itself. During my initial testing, I found that the output would not reach higher than 10 to 11 volts even with the over voltage protection set to the maximum value (20.5V). So clearly I have more homework to do, and for the time being let’s simply strip it down and see what’s inside.
I recently purchased a BSide ACM03 Plus clamp meter so that I could do some high current measurements for my tab welder project. This meter can be bought on eBay for around $25, which makes it one of the cheapest Hall effect clamp meters on the market that is capable of measuring both AC and DC current.
Since this is such a cheap meter, I wasn’t expecting much. But it actually feels really sturdy in hand and the construction looks reasonably solid, which is certainly a good start. It came with a nice little black pouch inside a non-descriptive cardboard box. It even includes a decent product manual.
Kerry Wong did a teardown of a battery adapter for the Sony A6000 mirrorless digital camera and measured the poweroff current draw of the the camera:
With the battery adapter on hand, I decided to take a look at what’s inside and then use the adapter to measure the power-off/stand-by current of the Sony A6000.
I was not expecting to see much inside this battery adapter. After all, all it needs is the connection between the battery terminals and the input power jack and a resistor between the center pin and the ground in place of the thermistor that is used to sense the temperature of the battery pack. At the most, it might also include a reverse polarity protection diode.
But a quick measurement suggested that there must be some active components inside as the adapter itself draws around 17 µA current when connected to the power source. So clearly, there is some active circuitry inside.
Upon opening up the battery adapter, I was surprised to see the circuit board inside.
The CMOS version of the commercially significant 6502: a processor architecture which launched the personal computer era.
This particular version was plucked off of an embedded industrial controller… a place where this processor still finds design wins.
In this episode Shahriar explores the principle operation of automotive FMCW radars. Thanks to a donated automotive radar module, various components of the system can be examined and explored. The PCB reveals three die-on-PCB ASICs responsible for generating and receiving 77GHz FMCW signals coupled to a 2D array of antennas. Several microwave components such as rat-race couplers and branchline couplers can also be observed. PCB rulers from SV1AFN Design Lab also show these microwave components at much lower frequencies. Two other ICs are used for ramp generation and PLL as well as a multi-input LNA/PGA/AAF with 12-bit ADC for IF processing. All components are examined under the microscope and the frequency of operation is calculated by measuring the branchline coupler’s dimensions.
Finally a simple Doppler effect radar is constructed by using a doubler, power divider, mixer and a pair of Vivaldi horn antennas. The Doppler effect can be observed by moving an object in front of the antenna pair.
A fixture on many British high streets are pound shops. You may have an equivalent wherever in the world you are reading this; shops in which everything on sale has the same low price. They may be called dollar stores, one-Euro stores, or similar. In this case a pound, wich translates today to a shade under $1.24.
Amid the slightly random selection of groceries and household products are a small range of electronic goods. FM radios, USB cables and hubs, headphones, and mobile phone accessories. It was one of these that caught [Julian Ilett]’s eye, a USB power bank. (Video embedded below.)
You don’t get much for a quid, and it shows in this product. A USB cable that gets warm at the slightest current, a claimed 800 mA of output at 5V from a claimed 1200 mAh capacity, and all from an 18650 Li-ion cell of indeterminate origin. The active component is an FM9833E SOIC-8 switching regulator and charger (220K PDF data sheet, in Chinese).
A straightforward teardown of a piece of near-junk consumer electronics would not normally be seen as something we’d tempt you with, but [Julian] goes on to have some rather pointless but entertaining fun with these devices. If you daisy-chain them, they can be shown to have the properties of rudimentary digital logic, and in the video we’ve put below the break it is this that he proceeds to demonstrate. We see a bistable latch, a set-reset latch, a very slow astable multivibrator, and finally he pulls out a load more power banks for a ring oscillator.
If only [MacGyver] had found himself trapped in a container of power banks somewhere from which only solving a complex mathematical conundrum could release him, perhaps he could have fashioned an entire computer! The best conclusion is the one given at the end of the video by [Julian] himself, in which he suggests (and we’re paraphrasing here) that if you feel the idea to be unworthy of merit, you can tell him so in the comments.
So, there sitting in a dumpster is what looks like a perfectly good monitor… some of the protective plastic on the base was never even peeled off.
A quick power up showed why it was tossed: it simply did not turn on.
I had been reading about the most likely failure mode was the electrolytic capacitors, especially in the power section. A quick disassembly quickly pointed out the likely culprit:
The bulging top is the give away. After replacing it with a capacitor from my parts bin the monitor powered right up looking really good. A fix that only cost me a few pennies.