Friday, 30 December 2016

Stuff

Cant think of a title for this post. The failed SMPSU has been refunded. No actual communication from the seller (apparently the sellers proper trading name is 'LeadCoo Ltd'), but a very prompt refund with no hassle.

Sadly, the cost of these supplies has over doubled! So ive ordered a replacement from a UK based (allegedly) seller. Ive also had to order more nut rivets for the mounting, and replacement fuses, as im all but out of them!

The IR remote control tester works nicely, but rather than continue with that now and try to fathom out a way to include 6v worth of battery and a 5v regulator into a 1inch mint tin, ive decided to instead power it from USB! To this end, a bit of shopping around on ebay found me ten micro-USB 'break-out' boards for a quid. These simply give you four PCB through holes on a 0.1" pitch, intended of course for SIL headers. But will allow simple circuits like this to be build dead-bug on the board.

Ive also finally got the box for the Theremin coming. Again that has proved to be far from cheap! But with any luck that will be another project complete and finished with soon.

Thursday, 29 December 2016

Infrared Remote Control Tester

Two things ive been pondering recently - how to test some potentially dicky TV remote controls, and what to do with a number of nice little metal mint tins I have,

well clearly the obvious thing is to build a little IR remote control tester!

I have some salvaged IR receiver modules amongst my junk boxes. It seems from what I can work out that these generally have an open collector output and run nicely on 3-5v, so it should be little more complex than giving it a suitable supply, and connecting a visible light LED to the output pin.

If it will work on 3v or less then a lithium CR2032 coin cell should power it for a good long while at the sort of very intermittent usage it will get, but it would be a very handy gadget to have.

To the workshop!

Well, I eventually found the IR receiver modules, in the box full of LEDs! I picked two out, one of which is a TSOP1738, and since this worked first time I haven't tried the other one.


Thats the best photo your getting, so deal with it! The circuit is so ridiculously simple for something so useful. A final version will need a few more parts to deal with the voltage requirement, sadly it doesnt work at 3v, so a pair of 3v coin cells and something to regulate it down to 5v will be needed. Probably a simple resistor and Zener diode will do. But other than the power supply, there really is nothing more to it than the IR receiver module, an LED and a 1K series resistor!

Ive tested this with all the remote controls I have to hand. Its interesting that some have much faster data rates than others. And as suspected, the remote for an Amazon Fire TV stick isnt IR!

Clansman 24V Power Supply - Major Setback!

The project to build a self contained 'battery eliminator' for the Clansman using a 24V 3A SMPSU has suffered a major setback today. Rigged up for its first live test, I switched on the mains supply - there was a blue flash and everything in the workshop went dark.

The supply had tripped the mains, right back to the main breaker in the house. On inspection, one of the mains fuses in the IEC socket was very much blown - it had literally exploded!

Checks for shorts etc done again, the fuse replaced, and this time the mains coming via the isolation transformer and a portable RCD, I tested it again. There was a brief flicker but then the RCD reset successfully - due to both fuses in the IEC socket having blown!

Inspection of the SMPSU module revealed it to have failed catastrophically.





In the top photo, and more clearly in the bottom one, there is a 'defect' visible in the solder. The two traces this defect was over are the DC output. It looked like a piece of loose wire had got soldered over the tracks (the actual bridging part of the wire had been blown off by the fault current!).

I later unsoldered this piece of wire, and found that it is actually the entire leg of one of the capacitors, nicked but not cut off, and bent right over the board by the forming machine and then soldered down by the wave soldering process.

This module was bought on ebay from a seller using the trading name 'Yall-UK'. I have contacted them. It is very clear that there is absolutely NO WAY this module could have passed any testing before being shipped. Lets see if they are willing to replace it.

Saturday, 24 December 2016

More on the Clansman 24V SMPSU Build

After posting the last entry, I remembered that i'd recently been upgrading the fans on my PC, and that some left over bits were on my shack desk. Amongst these were four self tapping screws, which turned out to be a perfect fit for the fan on the SMPSU build! So that fan is now very securely fitted.

After a bit of playing about with other things, such as testing the NEL Tornado coil on my detector in the garden (and finding 5p!), I returned to the problem of how to secure the SMPSU module in the case without being able to tighten anything up inside. A bit of pondering and measuring later, and I had the two mounting holes on the power supply module drilled out (in the case of the one that was a whole hole) or filed out (the other one, and open 'fork' type mount) to 5mm and a pair of Nutsert rivets installed. Now, the module had a pair of M3 tapped nuts permanently attached.

Quite a while was then spent deciding on the exact position of the module inside the case. I wanted to provide maximum airflow around it, but also keep it clear of the mains socket connections by at least a quarter of an inch. Having decided where it would go, the next difficulty was measuring and marking out where to drill the two mounting holes.


It is now fixed in the case. It will come out of course for the installation of other parts, for wiring up, and for testing. Still to be fitted are the output fuse holder and indicator, output 'on' and cooling 'on' switches, and the 12V regulator to drive the fan. I 'might' also provide a 12V output DC barrel connector socket, since the 12V will be available. I cant decide whether to mount these on the 'top' of the case, as seen when in use with the radio on a bench, or the bottom of the battery case.

I also have a problem in that im not sure if I should connect the DC negative lines to chassis! Something to research. If not, then i'll need to find an insulating kit for the regulator!

Clansman 24V SMPSU Build

With the filtered IEC socket installed, and the Earth Bonding Point, I mentioned the next thing to consider was what to do about the other previous cutouts in the 'front' of the case. Well, I cut them out!

I happened across a couple of small but really rather powerful fans amongst some salvaged equipment, plus a bit of old perforated aluminium sheet.


The first task was to drill a shed load of holes. No, its not an attempt at a Clansman Nipkow disk, but it does make it a damn sight easier to file the excess web out! I will give one bit of advice to anyone mental enough to decide to copy what im doing - drill out the mounting stud for the original DCCU charging plug first!


Once all the excess metal was out, I could then use a half round bastard to form the final circular cut. Or at least as near to circular as its going to get.


The vent mesh and the fan are bolted in in a sandwich. Im not happy with the bolts to be honest, as these only just have enough bite to hold the fan (and im one short!) so will replace these with self-tappers that will properly bite into the fan plastic when I can find some.


The pic above shows the fan in place. One thing to note about this, is that this is a 12V fan. But hey, this is a one off project, and im using mostly whatever I have to hand. I happen to have some 12V fans. I also happen to have some 7812 regulator ICs. So I can run the fan from one of those.

The next major problem to solve, is installing the PSU module. This is a problem, as its mounting holes will not be accessible once the PSU is in the case. So I need to find a way of bolting it in that doesnt require me to tighten it up on the inside!

A check of my other salvage found me another IEC panel socket with an earth lead attached. So now the power socket in the battery case is connected up to the Earth stud. I already have L and N cables ready.




Low Power UHF Data Modules - Audio Experiments

Any of you who play with Arduinos or R-Pi etc will be aware of the vast number of add-on modules available for experimentation. Amongst these are little UHF radio data link modules. Now, I used to use very high quality versions of these many years ago made by Radiometrix, but today you can pick up a Tx/Rx pair of these cheap imports for around a quid!

The transmitter of these is a little over half inch square, with just three connections for supply, ground and data, one for an antenna wire, and nothing more than a SAW (Surface Acoustic Wave) oscillator on the board! The idea being to simply use the data stream to key the device on and off, what is known as OOK (On/Off Keying, easy this radio lark init?)

But, thinks I, I want to send audio! Can it be done with these modules?

Well, sooo many people will tell you no, it cant. Or they will tell you you have to digitize the audio, or PWM the device. But is this really so? I mean, its really nothing more than a crystal oscillator, and we've all made simple 'bug' transmitters that are nothing more than an oscillator!

So I played with some ideas. Directly driving the data pin with audio didnt work. Neither did feeding the audio in via a transformer in the supply line. So I asked the wonderful folks who inhabit the G-QRP club forum, and was directed to Youtube for video of Peter Parker, VK3YE, experiments in a similar vein -

https://www.youtube.com/watch?v=vNMIIh4sCeE

Peter has made these modules do it! In a later video he shows a DC bias system that improves the results. So I copied this to see if it would work,


I used whatever was already lying on my overcrowded, untidy bench - namely a 47k pot and a 100uF electrolytic, plus various wires and leads. 100mV at 1kHz audio in from the test set, 10V DC supply,


And bugger me with a fish fork! It actually bloody works!

In this test, I seem to get considerable, reasonably clean FM deviation. On AM there is mod there but its not very deep. Varying the supply voltage does vary the frequency, and the modulation level. But it quite clearly works!

Next job is to actually listen to it, see how it sounds in a receiver. From then, the next stage will be to experiment with the Rx module to see if audio can be recovered from it. I suspect the LM358 IC on board is being used to 'shape' the output to reasonable logic levels, so might have to play around with this somewhat.

Friday, 23 December 2016

Clansman 24V SMPSU Build Started

With the transfer of the 4Ah 7S LiPO pack to its new home inside the metal cased 1Ah battery, that left the metal 4Ah battery case free to start building a mains PSU into.

There is one aspect of this which is of prime importance above every other consideration - Earthing!

This is a metal battery case. Its attaching to a metal radio. And im building a mains supply into it. I personally (dont know about the rest of you) like to live through my radio sessions. Plus, I learnt what mains voltage can do to a body at a very young age - having suffered a severe electrical burn aged only four, the scars of which I still have on the join between my index and middle fingers of my right hand, and the first knuckle of that index finger.

First task then, was to fit an IEC socket. The one chosen was salvaged from a piece of professional video coding equipment, and is not only fused but also contains EMC filtering.


This is installed very low into the bottom of the case, which did pose a tricky problem - how to fasten the nut underneath! The technique I used for that was to fit the nut, star washer, and the bolt through the hole, with another nut and washer on the outside. I could then adjust until the bolt only just was through the inside nut, and then tighten the outer nut up so that everything was in alignment and secure. I then used hot melt glue to secure the inner nut in place against the chassis, a sharp blade to cut away any glue over the hole in the nut where the bolt would come through. Once the glue was set, the outer nut was slackened, and the bolt withdrawn. Once the socket was in place, this bolt was then reinserted and very slowly and carefully tightened, so as not to disturb the glue until the star washer had a chance to bite and secure the nut.

The other nut and bolt of course I could reach to tighten. Those of you possessed of Action Man like Eagle Eyes might have noticed the other nut and bolt, in the bottom center. Here I used a drill powered wire brush disk to remove the paint etc from the chassis around another 3.5mm hole, and then added a cheesehead bolt, crinkle washer and nut, and tightened them to a damn good level of torque. Another washer and nut have been put on for safe keeping. This will be the Earth Binding Post, to which the SMPSU's earth terminal, as well as that of the IEC socket, will be bolted.

A good number of continuity checks were then made to this bolt from everything so far that had to be earthed.


From the outside, you can see that the socket is fitted off to one side. This, when the battery is attached to an RT-320 and the radio laid down for operating on a bench, will actually be at the top of the battery, and the Earth pin will be highest - exactly as you would expect to put the plug in.

The next problem, is what to do about the previously cut holes for the LiPo monitoring and charging. Ive decided the best thing here would be to expand this into one large square hole, and then mount, bolted behind it, a sheet of metal ventilation grill mesh, which luckily I salvaged off of some other bit of kit.


Once I have the grill fitted, there should be relatively little metal bashing needed. A few holes for bolts to attache the SMPSU, one for an LT fuse holder, one for an indicator lamp. Maybe one for an 'LT ON' switch, and perhaps an external 24V output.

Clansman 24V 1Ah Battery Rebuild - Complete

Much of the final work on the 1Ah case has been to get things secured inside, route wiring, ensure the battery is safe from any spiky bits etc. Liberal use was again made of hot melt glue and foam.



Once all the wiring was secured inside, the balance leads were connected up, the battery placed inside the case, and the balance connectors and wiring seated down in the space above the  D-connector. A sheet of cardboard covers the rivets on the side where the data plate is attached. Ive kept this plate for authenticity, even though it refers to a NiCd battery. The pack will also get a MOD record sticker at some point. The RED paint markings will identify that this is a special pack.


The screw terminals of the main power terminal block required some trial and error adjustment to get the wire form to fit effectively. Once that was secured however, the rest of the case was packed with foam, ready for the lid to go on.


Some rework was needed to the wooden batons within the lid into which the small wood-screws go to secure it, as these were far too thick for this case. But the lid is now on, and the pack tested. All that remains is to mark the bottom of the pack in red that this is a LiPo pack.

I can now use the metal 4Ah case for the SMPSU build.

Clansman 24V 1Ah Battery Rebuild

Some time ago I acquired a 1Ah metal cased Clansman battery, which after removing the old cells I had planned to build a 24V SMPSU into. Unfortunately, the Chinese PSU obtained doesnt quite fit - its a few mm too big!

So, I decided to build the mains power supply into the 4Ah metal cased battery, that had my LiPo battery in, and transfer the LiPo to the 1Ah case. This means the PSU will have plenty of room to 'breath', and a cooling fan, or at least a vent grill, can be added if required, as can a proper filtered IEC socket and any other items needed, such as protective crowbar and under/over voltage cut-outs.


The first task was to strip out the balance charge, monitoring and alarm wiring, and install these into the 1Ah case. The same technique as before was used - widening out the original DCCU charge port, and reusing its fixing lug for one of the bolts.


With the D connector fitted, the next task was to create the hole to mount the monitor and alarm display. This is 22mm x 14mm, or theres abouts. This was good old fashioned metal bashing with a drill and files.


Below is the battery and case in its present state of construction, connected for a wiring test. The bypass plug is attached to do this.


The next step is to secure the LED display in place, add the alarm LED and the buzzers, and secure everything in place ready to add the battery itself. Once the battery is in, all spare space will be foam packed, and the temperature sensor secured to the battery. Then  the lid will be screwed back on (after re-engineering the mountings), and all will be good, except for the final job of adding the safety markings to the bottom.

Ultimate 3S Beacon - Shiny Box!

A knock on the door yesterday from our friendly local postlady, put me in possession of a remarkably heavy box postmarked from China. For quite a while I couldnt think what it could be, being much heavier and bigger than a few DS18B20 ICs or a couple of Arduino Nanos. Then I remembered that the Ultimate 2S beacon kits bespoke case is shipped from the Far East.

I had planned on re-engineering the rear half of the case to provide a mount for a Clansman PRC-349 NiCd pack, but on seeing the case decided to keep it as intended.


The front panel was a fraction bent but will soon straighten out. In fact with such a panel its best to give it a very slight curve inwards, as then when secured to the rest of the case it will be under slight tension and form a good seal. There are two buttons, for the operating settings, and two switches, both SPCO. One is of course power, but the other is available for anything you wish to put it to.


On the rear is the power connector, a standard DC barrel connector with a switching contact, the RF out BNC, and a 9-way D-sub for the GPS and anything else you may need connections for.



 The GPS only needs four connections, which leaves five for other use, such as ICSP, or control outputs. Of course, a very simple way of getting many more connections would be to change the 9-way D-sub for a 15-way High Density D-sub!


The Ultimate 3S is now mounted on the front panel, but I have not yet connected it up. I do have one small problem now in that my recently installed SMA connector is now too close to the edge of the case to put the plug on! Looks like i'll be going back to using the pin headers for the RF output connection!

One very noticeable thing is the large amount of empty space in the rear of the case. Intended I think for building an SDR receiver in or adding the PA block. However, I want a QRP portable  beacon, so have begun pondering using this space to build in a 5V regulator and a 2S LiPo battery pack - using the spare D-sub pins for a balance charging connection.

Wednesday, 21 December 2016

Air Test on the NEL Tornado

By the time I had my new NEL Tornado 12x13" Double D coil installed on my Garrett Ace 250, done the Target ID mod, tidied up, put the pictures up for Julie, and collected my car from the menders, at a mere four ton and a pony for the privilege, it was too dark to do any actual detecting.

I was actually feeling strangely off, as my initial brief air test had seemed rather lacklustre. To the point that I was becoming a bit paranoid that something was wrong. So tonight I found time to pull up someone elses air test of the same coil on the same machine, put mine on exactly the same settings, and try again.

Ive not tested with actual gold yet, but the readings for various coinage in my possession are below -


Coin
Depth in Air/Inches
Notes
£2
12
Bimetal
£1
9.5

50p
11

20p
10

5p
7

2p
11

1p
8
2016 copper washed steel
1948 Half Crown
12

1942 Florin
12

1922 Shilling
9

1954 Sixpence
7

1917 Threepence
7
Silver
1943 Threepence
8
Octagonal Brass
George V Penny
12

1967 Halfpenny
10

1907 Farthing
9.5



These might not be particularly accurate, maybe out half an inch or so, and some of the 12" might even be deeper! My ruler isnt long enough to check! Plus, still learning how this coil behaves, I found the sweep speed has a bearing. They are all 'face on', edge on readings will be lower of course.

But, they do seem quite good depths to me. I will try and get some actual gold readings tomorrow, and also start compiling a list of target ID numbers for the above test coins, plus some typical trash.

Detecting Rules of Engagement!

Ive been pondering a quick reference card for the basic principles of the Treasure Act 1996 today. This came about as I can never remember the rules concerning how many coins constitute a hoard, and most of the explanations are rather wordy and not really suited to a quick pull out the pocket and go "Ah yes!" moment. So I have knocked up a little double sided aide memoir card. Its not finished yet and the details might not be quite right, but its the sort of thing I have in mind. Im putting a screen shot of it on here so I can link it to the MDF forum with a link thats a damn sight smaller than the one from Photobucket! And besides, im starting to lose confidence in Photobucket.


Today has otherwise been a detector day - but not detecting. By the time I had fitted my new NEL Tornado coil on my machine, added the Target ID numbers mod (a simple label 1 - 12) and cleaned all my kit, it was too dark again to go out! Testing the new coil will have to wait.

Thursday, 15 December 2016

Ultimate 3S - now 6-Band ready

Finally got around to completing the Low Pass Filters for 15m and 17m, and to adding the SMA socket to the relay board.


So now my Ultimate 3S QRP beacon is ready to go on six bands - 10m, 15m, 17m, 20m, 30m and 40m.

I still need to build a little 5v regulator unit to go with it, but I have all the parts for that, its just a case of bothering to build it. The official metal case for the beacon is on order. When that arrives, I will also obtain a suitable low profile plastic case for the GPS module, which I will then bolt on top.

I still need to test the new LPFs, but its not likely there will be anything wrong with them. I cant test them just now, as without the proper regulator card, I need battery power - and none of them are charged!

Dew Heater Progressing.... and then stops

With the display working, ive managed to make much more progress with the Dew Heater, but then sadly come to a stop.

The DHT22 humidity/temp sensor is now connected and working fine. The display now reflecting this data,

Unfortunately, it seems my DS18B20 temp sensor is duff. A later update to the sketch from the author also includes test sketches that return the data from the sensors via the serial link to the PC, and this shows error for the DS18. A meter check shows just 0.75V on the signal line for the parasitic power, when it should be around 4V, as it is if I pull the signal line and check it open circuit.

I dont have another of these sensors, so will have to wait now until spares arrive, however long that takes!

I have also discovered that the OLED display will run quite happily with the DC and CS pins open circuit, which saves a couple of wire links.

So it looks like thats it for this project for a while - lucky theres no clear skies again!

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.