As part of a prototype developed 12 months ago I was tasked with reading measurements from a blood pressure cuff [sphygmomanometer] in real time. Not surprisingly there are no consumer level devices that have a serial interface because what ‘normal’ person would want such a thing!
Initially we considered our own interface for a blood pressure cuff. Just run the pump and take the readings with our own processor and pressure sensor, how hard can it be. Rather difficult it seems, the processing and knowledge required to develop a device to perform even rudimentary readings would have completely blown the time budget. Instead we looked to hack an existing device, enter the Omron RS8.
Joonas Pihlajamaa from Code and Life writes, ” I’ve previously made a GPIO benchmark of Raspberry Pi 1 and 2, and have always wanted to see how BeagleBone Black would stack against the Pis. I recently got one so the obvious thing to do was to see how fast the little thing could go. Turns out, the little thing needed a bit more work than the Pi, but the results were quite interesting.”
I recently inherited a key on board (KOB) telegraph that my late grandfather used to practice Morse code with when he was a kid (Figure 1). A little bit of curiosity of how it would work and a little bit of displeasure from seeing it sit and collect dust, I began a journey to resurrect the old machine and develop some software to bring it into the digital age.
For this project I’ve used 12AX7 vacuum tube. This tube is one of the most used for the guitar preamplification. So there are many resources available on web.
The first problem i faced it’s the power stage. Tubes needs high voltage in order to work properly. The solution I’ve found was to connect a 230V/9V power transformer with secondary and primary reversed. That way, connecting it to the 10.5V AC output of the main Behringer transformer i can get almost 160V DC.
Any tube also needs a low voltage current to power up the heater. I choose to use a 7805 voltage regulator, shifted by 1.3 volts using two switching diodes. This gives me the 6.3V DC I need.
In my previous post, I did a review of the 6000 counts ennoLogic eM860T true RMS multimeter. This meter is based on a signal chip design using the versatile DTM0660L DMM chip. Besides the ennoLogic eM860T, several other multimeters such as UNI-T 139C, Velleman DV4100, Tekpower TP40 etc. are also based on the same chip.
One key feature of this chip is that most of the configurable parameters as well as the calibration data are all stored in an external EEPROM. This means that we could potentially change certain settings and enable certain settings (e.g. enabling UART communication, backlight duration, auto power off duration, etc.) by just changing values in the configuration EEPROM without having to do any hardware modifications. We will take a look at how to make these configuration changes in this post.
Here’s a geeky desk sockets project from Luke. He writes:
I wanted a few more functions than just a desk USB Hub.
Looking on the net i came across this youtube video . This was the type of thing i was looking for but it had far too many functions and too large.
I decided to list the things i would like:
1) USB Hub (powered)
2) SD card reader
3) Basic adjustable psu
4) Mains socket
I decided rather than making something scratch i would see if there was anything available i could just modify to fit all my criteria.