Dew Heater Progress - Eventually!

As usual, i've not found the easy path with this! For a kick off, it seems one of my two Arduino Nano modules is duff. Ok so they are chinky knock-offs at under £2 so im not overly fussed about that, although I would have preferred to discover this earlier. The other ran ok as a bare board with the L LED blink test sketch, and is still running fine after having the pins soldered on.

The next difficulty came with the actual sketch - it wouldnt compile! Many many reads of the error log later, and I had identified and installed all the missing libraries it was trying to access. And then -

It still wouldn't compile! This time it threw a more troubling error - 'dht' does not name a type. This resulted in having to read a lot of bumpf on the internet without getting anywhere, until I finally decided to completely read the entire thread on the project, and discovered an updated version of the sketch, written to address this very issue! It seems an upgrade in the Arduino program somewhere along the line knackered the handling of some libraries. Having obtained the new v.4 sketch, which is also updated for three dew heater channels, I found that it would compile and upload to the Nano nicely.

So now, I had a properly programmed Arduino Nano. Perhaps. I still didn't have a display on it so no idea if it was working. But, my OLED display is a 7-pin module capable of several interface protocols, and set up it seemed for 3SPI not I2C. I suppose a good programmer would just have changed the protocol from the controller. But im not a good programmer. So I decided to change the displays physical config.

The silkscreen told me I needed R1, 4, 6, 7, 8. R7 and 8 are already in place, as is R4. R3 was fitted for 3SPI, so I moved that to R1. No display. Ok then I need to fit R6...

These are tiny SMT resistors. My smallest is an 0805 4k7 which I had to 'tombstone' on the board and add a wire link to. Still no display function! So, download the datasheets. Generally useless as expected, but it did show that R6 was a zero ohm link! So, resistor off and solder bridged - and still no display!

Grrrr!

But, luckily then, back on the internet, I found this How to wire these bloody things up!

But this wasnt quite the end of it! I set Chip Select to ground. I set the DC pin to ground. Still no display. Then I did the one remaining option open to me (oh, did I mention swapping SDA and SCL over each time as well to check those?) which was to pull RES up to Vcc...

About bloody time! I don't think the link to Vcc is particularly healthy for RES so will change that to a 100k pull-up resistor later, which I will add onto the OLED display board itself. But I now have a working display. It shows errors of course as I haven't yet added the humidity and temperature sensors. I'll be doing those next, one at a time, the DHT22 humidity/temp sensor first, as this is what is used to calculate the dew point.

Hopefully the link above will help out anyone else who gets one of these awkward modules, although be aware just how tiny those resistors are! If your good with the code your probably better off changing the control protocol to match!

PG Tips

Oooh look! A video!

Alright so its not very well produced - hey I work in transmission not production! But anyway, this is a little video clip showing a tip I picked up, if I remember correctly, from Hans Summers. SIL header pins can be a bugger to solder in and keep them straight, so that they mate to the sockets properly.

Its a simple enough trick - just stick a spare bit of Veroboard or other perfboard into whatever you use to hold PCBs, pop the SIL headers in, and put the device on top. The board will keep the alignment perfect whilst you solder.

It is worth, however, finding out the separation between SILs before recording a video of it!

Anyway, I now have the headers soldered onto an Arduino Nano, ready to program with the Dew Heater sketch, and try and get the display running. It makes sense to do this on a breadboard for now, as im sure there will be a bit of tinkering needed with the wiring before the day is out.

Dew Heater Controller

I am going to claim that I have all the parts now for building the Dew Heater Controller, to keep my camera lens or telescope clear. I say 'going to' as the OLED display I have has more pins than expected, and im not sure it is actually build for I2C control, and not one of the SPI configurations. There are what look like resistor/jumper instructions on it but they seem a bit vague! It looks like it might be set up for 3 wire SPI, but I cant tell for sure yet.

The project I am recreating is this one here Arduino based Dew Heater which uses an Arduino Nano to read a combined temperature/humidity sensor (the DHT22) and a digital thermometer chip (DS18), to calculate dewpoint and to measure the heating element. A small MOSFET driver module allows PWM control of the dew heater strap, and a 0.96" OLED I2C display shows me what its doing.

Tomorrow I will connect up the Arduino Nano and the OLED, and program it up. If I get the wiring and config right then I should at least get a display! And i'll be able to build on from there.

The big astronomical event, the Geminids meteor shower, is this week, the peak being yesterday. It would have made no difference having the dew heater already built, as in true fashion with the British weather I cant see the bloody sky and havent for several days!

On a more positive note, I did manage to get out for a short session on my newly secured metal detecting permission this morning. I didnt have long since I had an important phone call at lunchtime and then meeting an old work mate for tea, cake and moaning in the afternoon. It was a bit too wet really, very muddy, but it gave me chance to try out an Android based tracking app called 'Tect-o-track' which is so good I have just battled Google Play's poorly designed log-in screens to buy the full version (at a bank-raiding £3). Sadly I didnt realise it wouldnt transfer todays track and finds data from the Lite version! So the app doesnt have the details of the partial Thimble find from today.

Since I will be soldering tomorrow, I'll complete the remaining U3S LPF modules as well. I have the official case for this beacon on order on the slow boat from China. Ive also ordered yet another OLED display, this time one specifically I2C (it only has the four pins Vcc, GND, SDA and SCL). Ive had no luck with these damn displays, and had to endure a fight with a previous seller to get a refund.

Detecting

Some of you may know that as well as amateur radio, Clansman radio, astronomy, photography, a bit of DIY and long distance walking, I also do a bit of local history research and metal detecting.

Up until now, I havent documented anything of my metal detecting, other than electronics builds, online, instead keeping record on paper. However, Ive decided that since its a fairly technical hobby in some ways, I will occasionally add my detecting experiences to this blog. Im not starting a separate blog as that will inevitably confuse me!

One thing I will not be doing though is detailing any locations! My current permissions are small, and very exclusive, and im working on building up a good reputation!

And Zebedee said - BOINC!

Ive just recently decided to get back into using my PCs idle time to contribute to scientific and medical research. I used to do this quite some time ago, when taking blocks of data from the Arecibo radio telescope and searching it for evidence of little green men was all the rage, but havent done so for some time.

Its been suggested to me that others might be interested in this and that I should mention on here how to get involved, so, I will,

Firstly, you need to know what it is your getting involved in! Essentially, your letting your processing power be used in an official and above board Botnet! But, unlike a spammer or other nefarious dude of the internet underworld, in this case your processing power is used for the good of mankind, or, at the very least, to help some very dull mathematicians solve hideously difficult and probably pointless equations involving prime numbers, and give them maybe enough of an exciting moment that just one might actually manage to pull a girl...

What you are doing is getting involved in Distributed Computing, as part of a Grid Network. Imagine the architecture of a supercomputer - lots and lots of processor cards rammed into vast racks, and all networked together. Now, imaging that each of those cards was not in a rack, but in someones home, office, mobile phone etc, and the network was the internet. Well, thats exactly it. A control server splits the work up into liddle iddy biddy meatballs, and sends a few to your device. Your CPU (and if you have a powerful enough one and your project can use it, your GPU) then crunches the numbers - so long as your not using it yourself. If you are, it waits until your not (or does less crunches) and then starts again. The result is that instead of sitting there bored and running windows idle processes, waiting for you to play, your expensive multi-core processor can happily get on with doing what it was made for. When its done, it sends the finished jobs back, does its best silicon Oliver Twist and asks for more, and the work server assigns you credit for a job well done.

So what do you need to do this? and above all, why would you?

Well, the why is because your a very public spirited and charitable person, and the chance to use waste PC time to solve sciences big questions, probe the mysteries of the universe, find cures for diseases etc, with no cost and little effort, appeals to you. That or your the sort of person who will keep adding PCs to try and be top of the score cards!

The what, again is simple. If your reading this blog, then chances are you have all you need - an internet connection, and a device with a decent CPU in it. All you need then is the client software, called BOINC. You can get this here https://boinc.berkeley.edu/ which will also explain more of what your doing. BOINC stands for Berkeley Open Infrastructure for Networked Computing. Once you have the client installed, you go to 'add projects' and simply select those that interest you. Only some of those listed are currently active, but if the one you choose isnt active it simply wont use any CPU time. You can play about then with settings to do with now and when the projects run on your machine. The website will explain that better than I can.  A few projects require specialist hardware so you can only take part in those if that hardware is available at the time. Interestingly though, one project for sensing earthquakes can use your mobile phones accelerometers and run on the Android BOINC client. Yes, you can do this on your phone too! And why not, chances are your phone has more processing power than the last PC you owned before your current one!

And then you just leave it to get on with it. Some projects do have graphics showing you what they are doing, such as SETI@home (searching for aliens) and Rossetta@home (protein folding analysis), but generally you just leave it to get on with it in the background.

The screenshot above shows my current active projects. Thats how it looks and thats all there is to it. Close the client and it will run in the background following the preferences you've set up.

If your PC is left on doing nothing you may as well do this and contribute!

Testing U3S now on 30m

Another LPF finished and installed on my Ultimate 3S beacon. This one is in the position 5 slot, so maintaining the increasing frequency order (40m in slot 0 on the main board, 30m in 5, 20m in 4, and so far 10m in slot 1)

So far its been received nicely across Western and Northern Europe, and into the central region, but also across the pond into Florida. Not bad for a touch under 23dBm into the antenna system, and that not perfectly matched.

The only gripe I have is that there is no clear space on the componant side of the LPFs to mark which band they are tuned for. I have written the band on the underside of the PCBs, but thats not visible when they are plugged in. I might mention this to Hans on the group, but I dont know how he could adjust the design to provide a write space, as the boards are very compact. Perhaps a few mm extra board on one end and a white silkscreen?

Ultimate 3S Relay kit

The relay board kit and extra LPFs for my U3S beacon arrived yesterday, so I found some time to work on them today.

As with all Hans' kits, its very compact but goes together very easily, excellent quality. I did find the nylon pillars were a bit awkward to fit due to being so close to other components, something that would not be a problem if the stand-off for the display was screwed into it, rather than the other way around. I removed my pins connecting the RF out, then realised I could leave them, and tried to put them back but couldnt clean the holes out properly and ended up making a mess of it! So they were left out permanently. Not to worry though, im unlikely to revert to single band operation.

The above shows the relay board fitted onto the U3S. This is revision 5 of the board, which includes a novel modification to increase the harmonic suppression performance, but it does require the highest frequency LPF (in my case 10m) to be left permanently installed in position 1. Position 0, that is, the LPF location on-board the U3S, I have left my other original filter for 40m installed. This leaves me four positions for my four new filters - 30m, 20m, 17m and 15m.

I have so far only completed building the 20m LPF, and so this is installed in position 4, leaving positions 5 (30m), 3 (17m) and 2 (15m). The only other thing to do is make sure that the correct 'band', that is, the relay position number, is set in the software so that  the corresponding filter is selected to match the operating frequency. I have already modified my two transmission settings for 40m and 10m to match the new filter arrangement.

I have also recently been trying to program some old Philips PRP70 series radios, but so far without success, despite having a genuine programming lead. I suspect theres a corrupt file in the software, as it throws up a run time error that seems to relate to file handling in MS-DOS. I have three of these radios and only really need to get one working, as that will go on 4m.

More bits ordered from the Far East are beginning to trickle in. Several cheap multimeters, just to give me some extra metering capabilities, but one of the little analogue meters ive had to have refunded, as it is totally dead! I suspect i'll be able to fix it so long as its not the coil in the movement itself.

Ive also received the 24v 3A SMPSU block, which, as feared, is slightly wider than the 1Ah clansman battery case i'd hoped to fit it into! I need to test it anyway first, but I think I will have to look out for a 4Ah metal cased battery to decell and turn into a mains supply instead. I could perhaps switch the casing on the LiPo pack.

Ultimate 3S WSPR Beacon Success

After some further testing, I moved the U3S into the shack today ready to go on air. Some advice from Hans Summers regarding the GPS module allowed me to get that working, and after a number of false starts due to settings, it went on air on 28MHz around lunch time.

Not a single spot!

10m conditions clearly not up to much today! Powered from a 12v 7Ah SLAB, via a modified 3v/5v regulator board (el cheapo, intended for Arduino and R-Pi prototypes), the U3S was working away quite happily, so I changed the frequency, swapped the LPF, retuned the DX-70, which was acting as monitor receiver, and moved to 40m...


And was spotted a dozen times on the first transmission!

Ive been running on 40m since then, at 10min intervals, heres the spots for the last 6h -

Not bad for a mere 200mW! Rather than try and explain what the U3S does when its running, ive done a little bit of a video of it. This shows it from just before transmission, when during the gap it displays the GPS data, to just after the start of a WSPR transmission

Immediately after transmission, the beacon calibrates itself using the GPS 1PPS signal, before putting the synthesiser into 'Park', that is, running but on a frequency safely away from the operating band, to keep it warm and so avoid drift,

I will try 10m again tomorrow.

Clansman PRC-349 on 6m?

The PRC-349 is generally shunned by the amateur community, being as it is the bog-brush haired back-stairs sprog of the Clansman range. Its quarter of a watt output power is mediocre at best, and its 150Hz tone squelch system makes it awkward to interwork with non-Clansman radios. But perhaps its biggest drawback is that it doesnt cover any amateur bands.

Shame really,

But should this be the end? Why cant it be converted? This is something ive been looking into.

There are a number of problems that would need to be overcome in order to move the 349 to somewhere it might be useful -

- Its coverage 37 to 46.975MHz
- Its tone squelch system
- Its 25kHz steps

Lets look at each of these in turn,

Coverage - ok, so its a good way from anywhere, but, the move to 6m (50MHz) from 46MHz isnt too far, and the front end might just adjust, if not, it shouldnt be too hard to retune.

Tone Squelch - The squelch system needs to see a 150Hz tone at >3mV at the discriminator output. Hmmm, shouldnt be too hard to inject a suitable tone here

25kHz steps - ok, so this is harder. But - we would also need to pretty much replace the Tx and Rx VCOs and the synthesiser anyway to convert the set, so the new control system would just be built for 10kHz steps as required.

Heres my thoughts - Replace the synthesiser and the VCOs with an Arduino Nano, and a DDS module. Most DDS modules have multiple outputs so one for Rx and one for Tx. The original switches could be reused, or other suitable types fitted to get easily selectable steps. The Arduino takes care of all that. The Tx mic audio would need to be modulated onto the Tx side of the DDS, I believe this is not too hard to do. Some waveform shaping I think might be needed though. The Arduino can generate the tone to defeat the squelch.

Perhaps a trial on the bench might be in order...

Ultimate 3S - It Lives!

In between boxing up parcels, and scaring kids with my S10 respirator (in my defense it is Halloween!) ive had chance to power up and configure, partially, my Ultimate 3S beacon -

I had a few difficulties at first, due to a crocodile with a wide mouth! It turned out that the crocodile clip I was trying to use had been over stretched and its teeth didnt quite come together, so my -ve lead kept falling out!

It took some time for me to become familiar with the menus and the setting process. I managed to eventually get my callsign and locator set, and a WSPR mode transmission set up. I then had to go Trick or Treating with Tom,

These are the pumpkins I carved yesterday, suffering intense cramp in my hand as a result!

Back in the workshop, timing was set reasonably successfully using my watch. The power output was a doddle to set though, although my QRP power meter and dummy load isnt calibrated! I used my Alinco 2m handheld to calibrate it roughly, by measuring the handheld output on the Marconi 2955, and then seeing what that power read on the QRP meter. With the one BS170 MOSFET, it seems I am getting a comfortable 1/4W, or there abouts. Frequency was more awkward. For a start, I wasnt at all sure what to set! Luckily I discovered the table of sub-bands in the manual, and was able to set up for the center of the band. Then I managed to eventually find my signal on my main radio, which is acting as test receiver.

I eventually worked out, after a few false starts getting great decodes of my own spurii, that I was about 4kHz off frequency. Without the GPS module in use, I had to do a manual calibration. The instructions for this turned out to be in the assembly manual, not the operating manual!

My frequency is now roughly in the middle of the operating window. My own decodes are a bit intermittent at present which im putting down to having set the synthesiser to turn off between transmissions, which I think is causing a bit of a chirp! The 'park' control in the firmware is for telling the synth what to do between active transmissions, so I will set that back to an 'on' state.

The above screenshot shows my WSPR signal, and the recent decodes.

Before I can put the beacon to air though, I need to build a 5V regulator board for it, to allow me to run it from a 12V supply. This is a task for tomorrow.