Server Moved to Linode
I just moved my site from my own server to linode‘s VPS hosting. So you should see some pretty significant performance improvement down the road.
Author: kwong
Backup and Flash Firmware using Arduino
A while ago, I did a tear-down of a Keithley 196 bench multimeter. Towards the end of that post I showed a picture of my breadboard setup for backing up the firmware EPROM (27128) in case I needed to re-flash…
MCP3903 Library
MCP3903 is a six channel Delta-Sigma A/D converter. It features six synchronous sampling differential channels which can be programmed to sample between 16 bit and 24 bit accuracy, the gain for each channel can also be programmatically set from 1…
Modify An Off-the-Shelf CP2102 Module As An Arduino Programmer
A while back, I wrote an article on how to use a CP2102 USB/UART converter chip in place of an FT232RL to program an ATmega328P using Arduino bootloader. Of course, not everyone has the time or wants to build one…
Arduino Library For LTC4151
LTC4151 is a high voltage I2C current and voltage monitor. It is capable of monitoring input voltage ranging from 7V to 80V with the onboard 12-bit ADC. It can also measure the high side current and an additional external voltage…
HP 436A Power Meter Teardown
HP 436A is a power meter capable of measuring RF power between -70 dBm and 44 dBm (roughly between 0.1 nW to 25 W) with a frequency range from 100 kHz all the way upwards to 110 GHz depending on…
A Digital Thermometer Hygrometer With Analog Displays
It seems that you can’t visit to a microcontroller website without seeing a digital thermometer/hygrometer build of some kind. After all, it is pretty easy to build and at the same time quite useful as well. In this post, I…
BJT In Reverse Avalanche Mode
Transistors operating in their avalanche regions are often used to generate fast rise pulses (see avalanche pulse generator using 2N3904). Many transistors can also avalanche when the connections to collector and emitter are reversed. When operating in reverse avalanche region,…
Extending DAC Resolution Using Digital Potentiometer
One way to extend the resolution of a digital-to-analog converter (DAC) is by employing a sigma-delta converter in software. The main disadvantage of such approach is the slow speed. Alternatively, we can use some extra hardware to extend the usable…
Testing of Two Three-Phase BLDC Motor Drivers
I was doing a project that needed a driver for hard disk spindle motors. While I could use a microcontroller to generate the required driving waveform sequence, keeping the waveform in sync with the motor rotation is actually quite tricky…
HP 6113A Teardown And Calibration
A couple of weeks ago I did a teardown of HP 6181C — a precision DC current source made in the late 70’s and early 80’s. This time around, I am going to show some pictures of an HP 6113A…
Arduino Libraries Uploaded to GitHub
Over the years I have created quite a few libraries for Arduino. I finally uploaded them to GitHub a couple of days ago so that they are now all at one place and are easier to find.
HP 6181C DC Current Source Teardown
HP 6181C is a lab grade 0 to 250 mA current source manufactured back in the late 70’s and early 80’s. There does not seem to be any pictures on the Internet for this particular model so I thought I…
Simple hFE Adapter For Cheap DMMs
Getting a rough measurement of the transistor hFE’s is useful when designing analog circuits. Unfortunately, only the lower end DMMs nowadays offer such functionality as it is becoming less and less useful to measure transistor hFEs in a world that…
LM92 Library for Arduino
LM92 is a 12-bit + sign temperature sensor from Texas Instruments. This sensor operates on the I2C interface and can achieve an accuracy as high as ± 0.33 °C within the typical temperature measurement range. I created a comprehensive Arduino…