Semiconductor curve tracers were frequently used in analog circuit designs many decades ago, at a time when discrete semiconductor devices were in dominance and ICs were scarce. While curve tracers are no longer widely used nowadays due to the ubiquity…
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 my APC Back-UPS XS1500 and the technique I used.
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 resist the temptation to grab…
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 small, otherwise you will need a big heatsink as…
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 reference as well. And in many cases…
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 earlier comment, I am going to show you the…
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 something similar. While…
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 be trust-worthy for any kind of serious measurements.…
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 this EEVBlog video. Many people have built…
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 rather daunting task to…
My seven year old 24 inch LCD monitor (Westinghouse L2410NM) started to flicker recently, so I decided to take a look inside to see what was wrong. Even before I opened it up, I had a pretty good idea of…
I bought an old Tektronix 2445 150 Mhz oscilloscope on eBay the other day. It was listed under “For Parts/Not Working” condition. Since the pictures in the auction listing suggested that the scope powers up and shows traces on all…
The current sourcing/sinking capability of the I/O pins on Raspberry Pi is quite limited. According to the Wiki page, the current limit for each I/O block (e.g. GPIO0 through GPIO27 combined) comes at only 26 mA maximum, which is only…
Neal from SchmartBoard sent me an MSP430F5172 development board to check out. This board, according to the website, was co-designed with the University of Colorado for itw educational needs. It is actually just a breakout board for TI’s MSP430F5172 mixed…
Last week, I discussed the construction of a network-capable temperature and humidity sensor using SHT21 and ENC28J60 with an ATmega328P microcontroller. In this post, I will show the results obtained so far and the techniques used to chart the data.