Search This Blog

Loading...

Sunday, 15 January 2012

So, how's the penguin?

I've been fiddling with my Pinguino board a little after the build I reported last time. I have, in fact, created a second board - this one will end up as my first Pinguino project. I would like to make a DDS signal generator, but this one needs to include a sweep function so I can more accurately measure crystal filters.

Here's the new board, you'll see that I have interfaced an LCD display, a keypad and if you look carefully you will see there is a rotary encoder there also:

The display has a really neat blue backlight, but is almost impossible to photograph:
I actually want to use a four line LCD display that I have here, I think the software needed to drive the four line display will be the same, I just wanted to start with something I am more familiar with. I am a great believer in build a bit - test a bit.

The keypad will be used for frequency entry, and I have that working OK - I wrote a test program to simply display the keypad entry on the LCD and that's working fine. The shaft encoder will be used to change the frequency steps by utilising the push click switch that's built into it and the rotary part will be tuning when in signal generation mode.

So far so good, but the DDS module I have here I used before:

http://g0mgx.blogspot.com/2011/08/dds-this-and-dds-that.html


This uses a AD9850 DDS chip, and at the time I was interested in the later AD9851 DDS but I couldn't find a way to buy the chip in anything other than the basic SMT package itself. A quick look on eBay suggests that you can now get development boards quite cheaply for this IC now so I have ordered one. It includes 6x clock multiplier on board so it should be easier to get extreme accuracy without spending a fortune on an accurate high stability high frequency clock module.

So, now I wait for a parcel from Hong Kong - why there aren't any in the UK I have no idea.

Time will tell, fun though, egh?

Monday, 9 January 2012

Penguin - you mean Pinguino!

Well,

For a few days I've been playing once again with Pinguino:

http://www.pinguino.cc/

It's an IDE that simplifies programming of PICs and the one I've built uses the 18F4550 PIC from Microchip. The board I have built is detailed here:

http://wiki.pinguino.cc/index.php/PIC18F4550_Pinguino

and it looks like this:


I had quite a bit of difficulty getting the IDE to run on Windows 7; previously I managed to get it running on Linux, but with some help from the Pinguino forum users, I was pointed at this tutorial:


Which has worked out just fine. The IDE is now running:


and this communicates with the board via a Bootloader that you have to program into the PIC. I accomplished this using my recent ebay purchased Olimex PIC board:

This board is directly compatible with the Microchip MPASM IDE and programming the PIC was a doddle.

Once the PIC was programmed and on-board my homebrew Pinguino I have managed to successfully download and run an initial test program to flash an LED. Not much to show for it, but good progress!

I'm planning to play some more with DDS and some other homebrew ideas I have; all of which will be PIC based.

Watch this space!

Sunday, 8 January 2012

Can we handle the power?

Well,

The ATU that I am making for Vince has finally neared completed. My mate Paul completed the drilling of the metalwork for me; after my recent experience with drill bits I decided to let someone who knows what they are doing have a go!

So here are some pics of the nearly finished article:

The quality front panel labels are courtesy of my recent e-Bay purchase of a Brother label printer:
The problem we have now is that the turns counter we bought has a metal front panel piece. This (which I thought was plastic) is connected directly to the metal shaft which in turn is coupled to the metal parts of the roller coaster and is therefore at full RF potential. This is dodgy because we don't want that potential near the user and also because the front panel itself is at ground; the screws holding the turns counter to the front panel are actually causing a short circuit.

An initial attempt at getting past this problem by using some isolating washers (the kind of thing you would use to isolate a TO3 transistor from a heatsync) between the screws and the two other metal bits has resulted in a rather spectacular light show at about 40-50 watts. Clearly no good, and even if it worked electricaly, the metal part of the turns counter would still be at full RF potential, dead ATU  users makes for little or no repeat business, so this is no use whatsoever!

I'm going to get my aforementioned chum Paul to try and make be a plastic shaft coupler... we will have to see how that works out.

You can see the offending article at the very top centre of this picture, it's all at full RF potential:

To finish, here's a recent picture of the Geddy cat:


Al good fun though, egh?

Tuesday, 3 January 2012

How did that happen then?

Well,

I've been trying to make an ATU for my mate Vince, G0ORC. We have been toying with the idea for some time, but have finally decided to cannibalise an old CAP Co Tuner that had a very broken turns counter. The parts have ended up inside a rack mount box and I have been slowly building these bits into a high power tuner. There are two chunky variable capacitors and a really well made roller coaster inductor:

Now, today I have been making a bracket to mount a wafer switch on, this is to be used to switch the ATU between the rig or a dummy load. Nothing complex going on here you wouldn't think.

I used a recently purchased set of drills, the result was rather astonishing:

This was a bargain set of drills from Maplin, fantastic!

I think the ATU is going to work out OK though, once I've drilled the holes I need, what do you recon?