Kerry D. Wong

I was doing some experiments which involves switching high voltages (>3 kV) under high current (>30 Amps) load. Although solid state devices such as SCRs (Silicon Controlled Rectifier, or Thyristor) or IGBTs are the ideal candidates for this kind of operations, the prices for these devices are through the roof (1, 2) when the breakdown voltage exceeds the 3kV threshold. I did have a couple of QIS6502002 6500V 25A IGBTs I bought on eBay many years ago but as it turned out they were quite fragile, a few minor overloads during my experiments was enough to destroy them unfortunately.

Gyroscopes nowadays are based on micro-electro-mechanical systems (MEMS) technology. They are low cost and extremely miniaturized. A device combing both a three-axis gyroscope and a three-axis accelerometers (sometimes these devices are referred to as 6DOF devices) such as the MPU-6500 for example can be had in a QFN package as small as 3 mm x 3 mm and under 1 mm in height. Before these MEMS devices gained mainstream popularity however, larger piezoelectric vibrating gyroscopes were used in many consumer electronics devices.

In my previous post, I designed and 3D printed a high voltage connector for my Bertan 225-20R high voltage power supply. The silicone high voltage wire I ordered had finally arrived so I made a couple of cables using the connectors I printed. A few of my viewers had questioned the suitability of using PLA as printing material in high voltage applications so I decided to measure the dielectric breakdown voltage of PLA and gather some real-world data. Continue reading ‘PLA Dielectric Strength Measurement’ »

In one of my previous posts, I did a teardown of a Bertan 225-20R high voltage power supply, which is capable of outputting 1mA with an adjustable voltage range up to 20 kV. The power supply came with a special high-voltage connector however (similar to the CMC series connectors from Connectronics Corp), but I wasn’t able to get a mating connection cable. At least not at a reasonable price. Continue reading ‘3D Print an HV Connector’ »

In my previous post, I did a teardown of my Array 3711A DC electronic load. And as I promised, this time I did some testing with it and also discussed some tips and pitfalls. Continue reading ‘Array 3711A Electronic Load Testing – Tips and Pitfalls’ »

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. Continue reading ‘Teardown of an Array 3711A 300W DC Electronic Load’ »

A couple of weeks ago, I got myself an Agilent U1731B LCR meter on eBay. These handheld LCR meters are quite expensive when new, but can be found on eBay for a fraction of the original price. Dave Jones at the EEVBlog did a teardown video on a better spec’d U1733C (and U1733B) meter a few years ago, I suspect that circuit-wise the U1731B would be quite similar to what’s inside of a U1733B. Continue reading ‘Agilent U1731B LCR Meter Teardown’ »

I recently bought a Noritake-itron VFD module off eBay. Noritake-itron specializes in making vacuum fluorescent displays for many OEMs. As such, there are many surplus modules being sold in secondary markets. The module I got has the model number CU20026SCPB-T26A, but unfortunately there’s not much information available on the internet for this specific model. Continue reading ‘Interfacing a Noritake VFD Module with Arduino’ »

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. Continue reading ‘Inside an Agilent 66312A Two-Quadrant Power Supply’ »

Have you ever wondered what is inside of a 15 year old commercial color projector? Well we will find out in this post today. As usual, a video of this teardown is included towards the end of the post. Continue reading ‘Extreme Teardown of a Panasonic PT-L780U 3LCD Projector’ »

I recently bought a few Peregrine Semiconductor‘s PE42420 RF Switch evaluation boards on eBay. The PE42420 is an absorptive SPDT RF switch that operates between 100 MHz and 6 GHz. Besides the obvious use as a single pole double throw RF switch, we will take a look at using it as an RF modulator due to its fast switching time (~300 ns) in this post. A video of the experiments discussed in this post can be found towards the end. Continue reading ‘OOK/FSK Modulation Using PE42420 RF Switch’ »

I did a teardown a while ago on a cheap eBay electromagnetic radiation detector, and if you recall the performance of that meter was mediocre at the best. This time around though, I’ve got a MEDA PLM-100 AC magnetometer. Since MEDA (Macintyre Electronic Design Associates) specializes in fluxgate and search coil magnetometers, this PLM-100 magnetometer is a piece of professional test equipment. In this blog post, you will see some teardown pictures and for those who want to see some real world actions you can take a look at the video included towards the end. Continue reading ‘Teardown of an MEDA PLM-100 AC Magnetometer’ »

IRIG time code generators (not to be confused with the ones used in video and film industry) are often used for clock synchronization among various connected equipment and is commonly used in power generation and distribution industry as well as in the military. In this blog post we will take a look inside a Datum 9300 time code generator from the late 80’s. A video detailing the teardown is linked towards the end of the post. Continue reading ‘Inside a Datum 9300 Time Code Generator’ »

I recently found a Hittite (acquired by Analog Devices in 2014) HMC624LP4E evaluation board gathering dust in my miscellaneous PCB bin and thought it might be a great little project to add a microcontroller interface to it so I can use it as a convenient digital attenuator in my lab. The HMC624LP4E had been replaced by Analog Devices’ HMC624A-EP but these two chips are mostly identical so everything described in this post can be applied to the newer HMC624A as well. Continue reading ‘Controlling an HMC624LP4E RF Attenuator Using Arduino’ »

I bought a USB wall outlet adapter recently so that I can free up my wall outlets while charging my phones and tablets. Of course, before putting it into use, I wanted to open it up to take a peak inside to see if it was properly engineered and at least to make sure that it would not be a safety hazard at the least. After all, this USB adapter is meant to be plugged in all the time. Continue reading ‘Teardown of an MVMT Dual USB Port Wall Outlet Adapter’ »