Kerrywong - kerrywong.com - Kerry D. Wong
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UPS Transfer Time Measurement 22 Aug 2013 | 05:18 am
Most offline/line interactive UPS‘ (Uninterrupted Power Supply) have a transfer time between 5 to 15 milliseconds. In this post, I will show you the results of the measured switch-over performance of ...
Tektronix 2213 Teardown Pictures 12 Aug 2013 | 04:29 am
I love old Tektronix analog oscilloscopes and I could not seem get enough of them. So when I saw a cheap “untested, unknown working condition” Tektronix 2213 listed on eBay recently, I just could not ...
Variable Power Regulator Using TPS5420 2 Aug 2013 | 05:38 am
I typically use linear regulators (e.g. 7805, LM317, etc.) in my projects. Linear regulators (especially the low dropout ones) are great when the load is light and input/output voltage difference is s...
Using REF200 As 100uA Precision Reference 14 Jul 2013 | 06:02 am
A few weeks ago, I discussed how to calibrate middle to low end DMMs using a precision voltage reference such as REF01. Of course, you can perform similar calibrations using a precision current refere...
VFD Clock – Putting Everything Together 1 Jul 2013 | 06:43 pm
After I completed the filament driver and the circuit to drive the multiplexed VFD segments, it is time to finish the VFD clock project I had in mind earlier. On the circuit side, there isn’t too much...
A DIY Vacuum Fluorescent Display Driver 14 Jun 2013 | 05:31 am
In my previous post, I showed a simple vacuum fluorescent display filament driver built using a 555 timer and a custom hand-wound, center-tapped toroidal pulse transformer. And as promised in my earli...
VFD Filament Driver Using 555 6 Jun 2013 | 05:50 am
I recently salvaged a vacuum fluorescent display (VFD) from a piece of old test gear. The VFD is a 13 digit 7-segment multiplexed display and I thought it would look great in a custom digital clock or...
Cheap DMM Calibration With Precision Voltage Reference 28 May 2013 | 05:21 am
Having a decent digital multimeters is an absolute necessity if you are doing any types of electronics work (see Dave’s DMM Buying Guide). Those cheap sub-$10 multimeters are usually too inaccurate to...
Avalanche Pulse Generator Build Using 2N3904 18 May 2013 | 06:18 pm
Avalanche transistors can be used to generate fast rise time pulses. Their usage in the hobby world was made popular following an application note (AN72) by Jim Williams and was further publicized via...
QFN Soldering Using SchmartBoard 10 May 2013 | 02:00 pm
I wrote a tutorial a while ago on how to hand solder fine pitched LGA/QFN chips using perfboards. While The technique illustrated works well with low pin count chips, for many people it is still a rat...
