Below shows the error (now corrected).

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I you have been following my progress here in Cumbria, you may remember a couple of months ago I produced a PCB for a generic PIC development board, and that I had this board professionally produced - a first for me. The whole exercise was very successful, however there were a couple of things that could have been better. The solder resist around all the ‘vias’ was one issue.

Over the weekend I finished the Cumbrian QuickSilver board layout, however the solder resist issue was still present, what follows is an explanation of why it’s there, and a solution that works here

EAGLE generates by default a solder stop mask for each Via (also for Pads and SMDs, of course). This means the Via is free of coating material. The solder stop mask is drawn automatically in the layers 29, tStop, for the top side and 30, bStop, for the bottom side. The size of the solder stop mask can be determined in the Design Rule’s Mask settings. See the values for Stop. By default the value is fixed to 4 mils. Minimum and Maximum are set to the same values therefore.

In order to have vias coated, EAGLE allows you to set the solder stop Limit in the Design Rules’ Mask tab. Here you can define a value which is dependent on the drill diameter of the via. Let’s assume you would like to set the Limit to 0.7 mm. Now all vias in the layout up to a drill diameter of 0.7 mm will be covered with coating material. All those vias that have bigger drills will stay uncovered.

Yep the solution was straight forward and found on the Eagle CAD FAQ’s, and is now embedded into my design rules

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]]> http://www.m0khz.com/?feed=rss2&p=394 http://www.m0khz.com/?p=392 http://www.m0khz.com/?p=392#comments Mon, 14 Jul 2008 05:00:14 +0000 M0KHZ - Kevin http://www.m0khz.com/?p=392 This is a very quick blog update sharing that I have now generated the gerbers in preparation for manufacture. Below is a snap shot viewed from GC-Prevue, a free gerber viewer.

I have sent the files across to Andrew for checking and am hoping to dispatch to the manufacture within a couple of weeks. I’m now relocating from the shack to the patio – looks like we’re getting the second half of the Cumbrian Summer this afternoon, and I’m going to enjoy the sun shine

End of update.

Below is an enlarged section of the PCB as you can see things are a little congested This is the first time I’ve attempted to layout a 4 layer board and it’s been an interesting exercise. The next stage is to create the gerbers to enable manufacture, however I’d like to take up Andrew’s offer of checking my work before I spend some serious hard earned cash!

As always, ‘click’ to enlarge, by the way the line through the LTC2208 is the separation between the analog and digital ground planes. Oh yes one final point I’ve tracked this board manually and NOT used auto-routing

End of update.

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]]> http://www.m0khz.com/?feed=rss2&p=387 http://www.m0khz.com/?p=386 http://www.m0khz.com/?p=386#comments Tue, 08 Jul 2008 15:50:17 +0000 M0KHZ - Kevin http://www.m0khz.com/?p=386 This is a short blog update sharing the status of my current projects in progress. I needed to do this to attempt to prioritise my efforts.

Cumbrian Q1SR near clone, all components have been procured, the PCB layout is probably 80% complete, steps to move this project forward:

• Finish PCB layout
• Run off Gerbers and send to Andrew for checking
• Print top and bottom foils and check footprints against actual components
• Make any minor mods required
• Send Gerbers off for manufacture

Priority: points 1 & 2 must be towards the top of the list!

HPSDR Pheonix, waiting for the remainder of parts to arrive from Al in the States, missed taemspeak this week, so not sure of latest status, however from last week’s teamspeak Al was waiting for a couple of long lead items to arrive before dispatch of kits to alpha builders.

• As soon a the remaining parts arrive, construction will re-commence.
• I don’t believe the 125Mhz clock will be part of this kit, and I assuming Phil has a solution to this issue?

HPSDR Penelope / CSDR integration, waiting for a ‘rigrunner’ to arrive before hooking up the individual supplies, this item has been outstanding for over 4 weeks now!

• Install rigrunner
• Hook-up interconnections
• Install new software and commission
• Test on air

This list may not happen, depending on the progress of Pheonix, if Pheonix flickers into life soon, I’ll bypass the Penelope / CSDR integration and wait for the arrival of Mercury J

Cumbrian magnetic loop controller, as predicted this is a slow ongoing project, bubbling along in the background, however with the arrival of the K2 the background noise on 20M with my 132’ doublet is over S9! I’m sure the loop will help here, so this project may see some progress shortly.

Gate Dip Oscillator, I have yet to mention this new piece of test gear on the blog, but suffice to say I’m pulling on together from parts from the junk box, the hardware is finished, PCB etched and drilled, just need some time soldering the few components required. This however is another background task.

DSP-10, This build is slowly progressing, the DSP has been ‘boxed’ the RF PCB is about 85% complete, and is currently on hold due to missing components, basically lack of funds have stalled this build. This project is once again a background task J

High Performance Analog Defined Radio (HPADR), this is a new project, hinted at a couple of posts ago, basically I’m about to embark on a new radio build, based around Martein’s excellent work. I predict the front end boards will be with me with a couple of months, this will mark the start of the build. I am currently intending to develop my own user interface, and am learning a lot through research of graphic displays and touch panels, I am nearing completion of my selection, and following Martein’s advice I will probably be ordering an EA eDIP320-8 intelligent module, it has a number of interfaces and I will probably hook it upto my generic PIC development environment and control it through I2C. More to follow on this shortly J

Sat here in front of the screen and not in the shack, I reasonably confident the above list represents what is currently on the bench here in Cumbria (although I might have missed something), as you can see there’s a lot going on, but as always I’m learning new things at every step. Isn’t that what the hobby is all about, it is for me.

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Now for the bad news, it’s good to have ‘true’ knobs and buttons again, but my fingers are too big! I’m sure I’ll get used to it very quickly, the bad news is (and I really hope my XYL doesn’t read this), I’m still not fully happy with the user interface, so I am going to build yet another rig, a high performance analog radio based on the work of Martein - PA3AKE’s designs, but will spend a lot of time (and learning) developing my own interface using a large graphic LCD with a touch panel interface! This is going to be a very slow build and the K2 is definitely STAYING!

End of update.

As good as the K3 is, I do not believe this radio is suited to opening up the covers and modifying to suit my needs / curiosity, the K2 certainly is, this has been the main reason for my decision. I have also been lucky to find a pre owned K2 with the majority of options fitted at a good price, it’s a late serial number, constructed by a very competent radio engineer and has seen little use and no field use.

My recent eBay sales have almost funded this purchase and to cap it all, my XYL is pleased with my choice as she’ll now have more funds at her disposal for our Australian adventure in September .

Over the weekend I have been making preparations in the shack, and am now ready to plug and play when the K2 arrives.

I have a number of ‘extras’ I’m already contemplating, and here is the start of my wish list (not in any particular order):

• Swap out the analog audio filter and replace it with the DSP option.
• Modify the VOX circuitry to improve performance.
• Design an SSB pre-filter board to plug into the noise blanker header, to steepen the slope and improve strong adjacent signal handling.

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A while ago I shared the excellent work Martein is doing and the extremely good IP3 figures Martein is achieving with his design.

While Martein has been busy developing a high quality 1Ghz LO, interest in the front end design has steadily grown, Martein is now investigating the possibility of getting the boards professionally produced and has secured a good deal for the QT cut crystals which are needed to obtain high intercept.

I highly recommend a visit to Martein’s site, here is the link:

http://www.xs4all.nl/~martein/pa3ake/hmode/pcb-query.html

Here is an opportunity to acquire a full set of professional boards for your next HF radio project, or use as a set of bandpass filters for say HPSDR / Quicksilver etc.

Read the information on the site and send an email to Martein before he closes the list

End of update

The story really starts back in the mid 1700’s, when scientists in Holand and Germany found that, if you applied a voltage using static electricity, the Leyden Jar could store charge. This was the first capacitor and the first basic circuit element.

Fast forward to the 1820’s, and Ohm was figuring out that every wire had resistance and that resistance was related to voltage an current. Resistance was the second basic circuit element.

About the same time, Faraday was winding wires into coils and discovered the relationship between electricity and magnetism. The inductor was the third basic circuit element.

Since then nothing has happened, these three basic elements - capacitance, resistance and inductance - allow simple equations to be written relating voltage, current, charge and flux. And it is here that a clue appears, flux is often thought of as relating to magnetism and we look at flux in terms of how much voltage has been applied.

Now the story leaps to the present day - or at least to the 1970’s. Leon Chua joined the Electrical Engineering and Computer Sciences Department at Berkeley, where he is now a professor, in 1971.

Chua looked at the basics of electronic circuit design and saw something perplexing, although he saw four variables, he could only see three circuit elements. He believed something should be there to link two of the four variables - charge and flux.

When he worked through the maths, it started to get interesting. From his mathematical analysis, he determined that, if a fourth element did indeed exist, it would look like a resistor with memory. Not only that, he believed that such a device might also ‘remember’ how much charge had flowed and for how long. Effectively, such a device would change its resistance according to recent conditions.

OK so we now have a grasp of the background to this missing forth element, and we now need to explore ‘Quantum research’.

HP Labs has been researching the nanoscale for some years now and has set up the Information and Quantum Systems Lab 12 years ago. Heading the Lab, which is focused on turning fundamental advances in areas of mathematics and physical science into useful technologies, is Stan Williams. During the past 12 years, Williams and his team have been researching the fundamental limits of information and computing and this work has led to a series of breakthrough discoveries. As part of this work, Williams’ team has seen things which defied explanation, and it was while trying to understand and explain these anomalies the realisation of the physical memristor occurred.

“Part of what’s going to come out of this is something none of us can imagine yet,” says Williams. “But what we can imagine in and of itself is actually pretty cool.”

For one thing, Williams says these memristors can be used as either digital switches or to build a new breed of analog devices.

For the former, Williams says scientists can now think about fabricating a new type of non-volatile random access memory (RAM) - or memory chips that don’t forget what power state they were in when a computer is shut off.

That’s the big problem with DRAM today, he says. “When you turn the power off on your PC, the DRAM forgets what was there. So the next time you turn the power on you’ve got to sit there and wait while all of this stuff that you need to run your computer is loaded into the DRAM from the hard disk.”

With non-volatile RAM, that process would be instantaneous and your PC would be in the same state as when you turned it off.

Scientists also envision building other types of circuits in which the memristor would be used as an analog device.

Indeed, Leon himself noted the similarity between his own predictions of the properties for a memristor and what was then known about synapses in the brain. One of his suggestions was that you could perhaps do some type of neuronal computing using memristors. HP Labs thinks that’s actually a very good idea.

“Building an analog computer in which you don’t use 1s and 0s and instead use essentially all shades of gray in between is one of the things we’re already working on,” says Williams. These computers could do the types of things that digital computers aren’t very good at — like making decisions, determining that one thing is larger than another, or even learning.

It’s very early days, but I’m sure we will be seeing a lot more about the memristor in literature over the forthcoming months and years!

End of update