Hey, so its been a while, there’s been a few projects since the last post, but I haven’t written them up 🙄 .
In an effort to stop the projects accumulating in the half-finished pile, I made an effort to take this project that has been sitting on the workbench for ages and put it on display. Its simple enough but I’m pleased with the result.
Ages ago I wrote some code for an HTU21D temperature and humidity sensor. I made an outdoor housing for the sensor and all, and used it for a while, but the display was a bit impractical. Anyway, this time I used a 2 line 20 character VFD (vacuum fluorescent display) I’ve had for years (sitting in the bits and pieces pile) to display the sensor measurements. I’ve always liked the display and now its time to show it off.
Recently I saw you can buy heatshrink tubing cartridges for Dymo label makers. This would be really convenient to make professional looking markers to identify individual wires and cables in some of my larger projects. (Cable and wire markers for industrial applications such as these have been around for at least a decade now, but are pretty expensive. This solution from Dymo seems to be somewhat more mainstream, but it still is too expensive for the hacker)
However, my hopes were dashed when I realised that the cartridges aren’t compatible with my $35 Dymo LetraTag. Also, each cartridge is $50, so I wasn’t keen on buying one hoping that I could get it to work with my label marker.
So I got thinking about making my own and I managed to cobble together a somewhat effective method using some regular heat shrink and some 180 grit wet & dry sandpaper.
Following on from a previous post discussing the Analog Devices AD587 precision 10.000V voltage reference, I built a portable device to utilise the chip.
Some requirements of the project were:
10.000V ±5mV output
Battery operated device
Visual, low battery indication
Small, aluminium housing
Clear front panel
Low cost (under $50), readily available components
A low battery indication was a desired feature to prevent the device being used in an important test and the battery level drops low and compromises the AD587’s performance. A simple green LED will suffice. Output performance of 10.000V (± 5mV) couldn’t be compromised so there is no protection to prevent high current draw from the chip, I’ll just have to be sensible.
Voltage references are a humble piece of hardware, their sole function is to provide a stable, known voltage. This constant, known value of voltage can then be used as a reference for ADCs and DACs as well as provide a precision current source.
This model of chip has an output value of 10.000V ± 5mV (that is, an output value of 9.995V to 10.005V) straight out of the factory. A voltage drift of 10ppm/°C at 25°C meaning that the output voltage will drift by 10μV for each 1°C the chip is exposed to. Additionally, the chip has a voltage trim input, so if you have access to a precision voltmeter, the chip’s output value can be adjusted even closer to 10.000V.
If you are using Autodesk 123D Design to create your models, it will generate your STL files in ASCII STL format. XYZware is slow to load large ASCII STL files. Slicing an ASCII STL file can take a very long time too.
Fortunately, there is a solution. Saving your STL files in a Binary format will result in improved load and slicing times.
Converting your ASCII STL files to Binary is very simple. This simple guide shows you how.