Stew’s Spot

Just a quick update on the DDS Function generator project. I’ve just finished designing and laying out the power supply module. It’s a very basic design that uses 4 linear regulators to output 15V, 5V, GND, -5V, -15V. It’s not the most efficient design but because the system will not be using huge amounts of power, I think it’ll serve quite well, and because it’s a module if heat does becomes a issue it can always be replaced with a more efficient switch-mode supply.

Above is a quick 3D rendering of what it looks like at the moment. For scale, it’ll easily fit in the palm or your hand.

I’ve finally finished the Dual Battery Switcher page. Let me know if there are any glaring errors or spelling/grammar problems.

Ah you’ve got to love long weekends.

I spent some time this weekend doing the initial design work on a new project that’s in the pipeline.  I’m building a DDS Function Generator for the workshop,  nothing too fancy (I can always borrow the work one).  It’s based around the AD9834 from Analog Devices and the goal is for it to have all digital controls, that includes the signal gain and DC offset, with Sine, Triangle and PWM outputs between 1Hz and 10MHz.

I’ve completed the basic design, but there are still some finer points to finish and simulate. The next step is find and source the parts that I’m going to use then complete the schematics and layout the PCB’s.  I’ll post on the progress.

At least the workshop is looking a bit more “used” than in the other photos.

I’ve been working with this really nasty switch bounce generated by a multi-pole toggle. And as you can see on the scope trace, it bounces around for almost 1ms before settling.

Moral of the story? Nothing, I just found this quite interesting.

Some photos of my Agilent DSO1002A Oscilloscope.

On Saturday I decided that my workshop need some more shelves over the workbench.

Work in progress…

And the final result looks pretty good, I also hung up some extra storage boxes and a bigger whiteboard.  There is enough depth on the new shelves to easily store equipment on it, the only problem now is that it casts a shadow on the bench from the florescent light on the top shelf.  I’m going to have to experiment with lighting under the new shelves to fill this shadow.

I’ve been using Globat as my hosting provider for a couple of years now.  The problem that forced me to change was that you don’t get ssh or root access to your webserver. This means that you are stuck with what ever languages and features you hosting provider installs.  I wanted to run a git repository and ruby stuff, so I was out of luck.

I’ve moved all my hosting to Rackspace Cloud servers.  This gives me a virtual Linux box that I can do what I like with.  At the moment I’m running on the smallest VM (256MB RAM and 10GB HDD).

So if you notice anything funny, ie missing images or links that don’t point to the right page.  Just drop a comment so I can fix it.

National Electronics Week expo was on the 9th-10th March.  For those that don’t know their website describes it as

NEW SA 2010 is an all-encompassing event delivering dedicated support for every electronics sector. Business opportunities, networking platforms, seminars and conferences, this is a first for South Africa

Lately the expo’s in South Africa have been going downhill, so it was a really nice surprise that NEW was so well attended both by the public and the vendors.  I went to both days, missed the Microchip nanowattXLP talk on the Tuesday, it was a great show and really got the grey matter working with new ideas and technologies to try, plus there was swag to be had.

You can follow them on twitter @NEW_SA_Expo

I’ve been looking for some video editing software for Linux, it was not a big need so I never really spent much time looking and testing.

On Sunday I wanted to edit a shot clip and kdenlive was recommended to me by a friend. So I gave it a try.  All I can say is WOW what a pleasure to use.  It’s fast,  easy to use and seems extremely powerful.

So if you need to edit video on Linux (or Mac), I can highly recommend kdenlive