Kerry D. Wong

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.
Read more…

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.
Read more…

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.
Read more…

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.
Read more…

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.
Read more…

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.
Read more…

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.
Read more…

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.
Read more…

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.
Read more…

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.
Read more…

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.
Read more…

Recently I got hold of a dead APC SurgeArrest power strip that was about to be thrown out in my office. The power strip simply doesn’t provide power to any of its outlets regardless of the power switch position. Since there was no external fuse that I could find, I decided to take it apart and find out why and how it had failed.
Read more…

In my last post, I did a teardown of the Keithley 775A programmable counter/timer. And while feeding a 10 MHz signal from my Rubidium frequency standard, I noticed that the measured frequency was significantly lower (9.9981 MHz) than the nominal 10 MHz reading and could not be compensated by adjusting the TCXO fine adjustment screw alone. My suspicion quickly turned to the temperature controlled crystal oscillator (TCXO).
Read more…

I just picked up a Keithley 775A programmable frequency counter from eBay. Specification-wise, this counter is very similar to the Racal Dana 1992 frequency counter I repaired last year. The Keithley 775A I got came with an additional channel (option 7751) and is capable of measuring frequencies up to 1.3 GHz.
Read more…

There are a lot of cheap electromagnetic radiation testers out there which boast some quite impressive claims. So I decided to pick up a popular one (GM3120) from eBay to see how well it works. And perhaps more importantly, I wanted to take a look inside to see how the E field and H field sensing is done.
Read more…