Archive for the ‘Miscellaneous’ Category.
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 solder these tiny chips that way. Also, as the pin count increases hand soldering without using a board with proper footprint becomes much harder. Continue reading ‘QFN Soldering Using SchmartBoard’ »
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 what might be the culprit. These older LCDs use CCFLs for back-lighting. CCFLs are typically quite robust. While it is not totally impossible, it is rather rare to see a failed CCFL. So most likely the issue is related to the power supply module. Continue reading ‘Westinghouse L2410NM LCD Power Supply Repair’ »
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 channels, I thought I would get it and fix it up. Continue reading ‘Tektronix 2445 Teardown’ »
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 capable of driving a couple of LEDs at a time. Also the I/O pins are 3.3V only, and going beyond the current or voltage limit could result in permanently damages to the chip. Continue reading ‘A Bidirectional Level-Shifting Buffer for Raspberry Pi’ »
I got a used BK Precision 4011 5MHz function generator recently. The 4011 model is rather old and this particular unit was manufactured back in 1996. But BK precision still makes a similar model (4011A) which is identical to the older 4011 spec-wise except for the inclusion of an additional INV button for inverting the output waveform. Continue reading ‘BK 4011 Function Generator Teardown’ »
I got myself a Raspberry Pi (Model B V2) last month. After having played with it for a while, I have to say that I really like this tiny single-board computer. Since it runs on Linux, you can compile and run your C/C++ code on it. Most popular applications have already been adapted to the ARM architecture and can be run readily on Pi. Unlike some other SBCs, Pi allows easy access to GPIO ports which makes it equally attractive for people who are interested in hardware. Continue reading ‘Adding a Barrel Jack And a Switch to Raspberry Pi’ »
It is well understood that resistors are typically binned in such a way that for a given tolerance the actual resistance values are distributed within the specified tolerance but are outside the range of the next tighter tolerance specification. So for instance, when you buy a bunch of 5% 100K resistor, you can expect the values to be between 95K and 99K or between 101K and 105K. Values between 99K and 101K will be missing as they are binned as 1% resistors. Continue reading ‘100K 5% Carbon Film Resistor Value Distribution’ »
I have been mainly using perf-boards for my electronics projects. Since most of the stuff I build are not very complicated and are one-offs, using perf-boards has been more than adequate. With that said, I did find wiring the headers in my Arduino projects to be a big pain and depending on the number of break-out pins needed to be wired this could be quite time consuming and error-prone as well. Since I have heard many good things about Seeed Studio‘s Fusion PCB Service, I decided to give it a try. Continue reading ‘Arduino Dev PCB Using Seeed Fusion PCB Service’ »
Based on some user feedback, I have updated the Hex/Bin/Dec converter and calculator I created a couple of years ago. Added features include shortcut to clear all fields and additional calculations besides bits manipulations. Continue reading ‘Hex/Bin/Dec Converter And Calculator — Updated’ »
So far, I have shown examples of using the open source MCP2210 library with MCP2210 GPIO, MCP23S08 and TC77 temperature sensor. In this post, I will show an example of interfacing the chip with an SPI EEPROM using the library. Continue reading ‘MCP2210 Library — SPI EEPROM’ »
I made a few minor tweaks to the open source MCP2210 library during the past few days, and had also updated the documentation. In my previous post, I illustrated how to manipulate the GPIO pins using this library and today I will show you an example of communicating with a MCP23S08 8 bit IO port expander using SPI. Continue reading ‘MCP2210 Library — SPI Example Using MCP23S08’ »
Over the past couple of weeks, I had been busy playing with Microchip‘s MCP2210 USB to SPI converter. I was planning to create a Linux based API since Microchip only provided the Windows version. What I quickly found out though was that the oscillator circuit for MCP2210 was quite finicky, and it took me a while to find an alternative solution. Continue reading ‘Finicky MCP2210 Oscillator’ »
I bought an ODB II code reader to diagnose a check engine light problem of my car. The reader I got was an Autel MaxiScan MS300. This particular model is very popular as it is rather inexpensive, coming in at just around $20. Out of curiosity, I decided to open it up and take a look of what is inside. Continue reading ‘MaxiScan MS300 ODB II Reader Teardown’ »
I finally got some time to play with the STM32F4-Discovery board I received last year. As for any microcontrollers, learning how to manipulate GPIO pins is always a good place to get started. Continue reading ‘Driving 8-Bit Parallel DAC Using STM32F4-Discovery GPIO’ »
A few of weeks ago, I wrote about a couple of cheap webcams I bought from Amazon. Since the focal lengths of those two seemingly identical webcams are different, I could not use them in stereo vision experiments as I had originally hoped. Continue reading ‘Best Use of Cheap Webcams’ »