At last a Blog

Well I've messed about for a while thinking about a blog, I've done a web site, well out of date now, but at last it's time try blogging, here goes .....

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Chronograph update

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When I made the smaller screw on sensor that connected to the PC and fed the timing into a PC application, it got me thinking about different types of display that could be used and after a a good look around the net I came across a couple of options.

The first was a 7 segment LED display, these come in different shapes and sizes and could still be quite portable when added to the sensor.

The only problem with these displays is the amount of IO needed to drive them as each of the segments require driving. I then came across the Adafruit 7 display backpack, which takes all the hard work out of controlling the 7 segment displays.
The backpack details can be found here
The device is based on an Holtek HT16K33 chip that controls the LED segments and connects to the Arduino via the I2C bus and has a library that makes sending data to the display easy.

I bought one of the displays from Ebay and stuck it on the side of the sensor tube then added the code to the sketch to send the value for f…
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DIY Chrono Shopping list

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A few people have expressed interest in making a DIY chronograph so I said I'd put together a shopping list.

There are quite a few options for the display type so I try to give the pros and cons at each step.

Firstly, the processing power.
All my projects are done using the Arduino family, including the many clones out there, I've used original Arduinos and Clones from China all without any problems. (A PIC Micro will do just as well with the same hardware)


Arduino Mini Pro Arduino Nano

These are available in 5V 16MHz and 3.3V 8MHz versions, I used the 5V versions @ 16MHz to get the best uSecond resolution, I believe that the 5V versions can be run at 3.7V and still run at 16MHz. This device needs an external USB to serial adapter to allow programming but, once progr ammed, can be fed from a 7V source via the on-board regulator (RAW input) or a regulated 3.3 to 5V supply on the VCC pin. I bought mine on Ebay from here for less than £3 but it took 27 days to arrive. Others on Ebay sea…
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Chronograph completed - Finally

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As anyone who's read this blog before will know, there's a common theme throughout, the DIY Chronograph I made for measuring the speed of an airgun pellet.

Well since getting a 3D printer I've finally managed to finish off the project and put it in a case, it's not often I actually put things in a nice case.

The first case with the Nokia display, it was a bit clunky and easy to break, when I dropped it that is!

Second attempt, this is the one I've been using.  This one uses the Bluetooth module to talk to an app on the phone here
The final one, this one contains all the gubbins from the shot above inside the cover.

This one uses the Bluetooth adapter and connects to an app on the phone and has an internal lithium Ion battery than can be recharged using an external supply and charging module, you can leave out the battery and use the USB connector of the Nano to power the chronograph from your laptop or a battery pack with a USB power output. (if you do this then th…
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