Homepage update and new project

Hi Ruud,
Thank you fot he info. I will have a look at that. Really strange, as it was working two weeks ago when I updated the page, and the computer has not been touched. The index files are there, and the other projects I uploaded are there.

Until then you can use http://sm0vpo.altervista.org/power/diy_txfmr2.htm for that project, and I will be in a position to check the server in just over a week.

Thank you for the info. best regards from Harry - SM0VPO

Maybe it is only here (or only today), but it seems the 'Simplified DIY transformers for tubes' link doesn't work. Just sayin'...
(404, not found)

Hi Glenn,
Yes, there are loadsa sites that can print these 3D models.

The coil project does need a bit of work, tapping the M3 inner and fitting the bolt/ferrite. Probably better to make it yourself.

I can make a couple for anyonme, but at a few hours per print I couldn't do it for money. If you (or Ivan) want one I can sent you one to play with :-)

the idea was that anyone can play with 3D if they have a printer, a printer at school, or a freind with a printer, then they can experience tha days of the Denco era :-)

BR Harry (Still in Spain, no radio gear)

Admin wrote:
...
Have also included the 3D-Max file, the STL file, and the printer GCODE file.
...
BR Harry

The 3D models can be printed anywhere:
https://www.3dhubs.com/

Hello Ivan,
Thank you for the information. It was interesting to read the info, and I didn't realize that laser engraving was so cheap.

if you do try the black-pain etching method I would be grateful if you could share the result. That is something that I think is interesting.

My 3D printer is based on an Arduino, I the though crossed me that I could replace the print nozzle with a UV LED, focused to a spot, then use it as a plotter to expose a PCB photo-resist. I think tha basic problem would be the resilution as I would want 0.2mm minimum, and that is a very small spot. It would have to be a laser with some form of optics.

But printing speed could be quite fast if the laser was sufficiently strong.

Very best regards and thank you for the information. I am sure that there are other interesting in this sort of information.

Very best regards from Harry - SM0VPO
(I must go to bed now, still at work!!)

Hi all,
a homemade 3D printer can be extened to a laser engraving machine. All you need is a powerful (1W at least) blue or infrared laser, which replaces the melting nozzle. For those who prefer a ready-made device, see e.g.
https://www.aliexpress.com/item/KKmoon-1000mW-Miniature-Laser-Engraving-Machine-Carving-Engraver-Carver-AC100-240V-Automatic-DIY-Handicraft-Wood-Burning/32827448448.html?spm=2114.search0104.3.22.boVaMN&ws_ab_test=searchweb0_0,searchweb201602_3_10152_10065_10151_10068_10344_10345_10342_10343_10340_10341_10304_10307_10060_10302_10155_10154_10056_10055_10054_10538_10537_10059_10536_10535_10534_10533_100031_10099_10338_10103_10102_5590020_10052_10053_10107_10050_10142_10051_10171_10084_10083_5370020_10080_10082_10081_10110_10111_10112_10113_10114_10312_5610011_10313_10314_10078_10079_10073-10102,searchweb201603_17,ppcSwitch_5&btsid=779dd57d-b6ab-4284-9b59-c5cb3b760a67&algo_expid=144e9456-c7c8-4a6d-8b8e-368546967e70-3&algo_pvid=144e9456-c7c8-4a6d-8b8e-368546967e70
I was surprised how cheap are such beasties now.
It can be used for making durable panels for your devices from plastics or wood. I found recipes how to make PCBs on the web, too. Generally such small lasers cannot carve copper foil directly. The method is to cover the board with black spray paint, carving the pattern into the paint layer and then etching the copper foil chemically. I have not tested it yet.

BR from Ivan

At last, I have SSH:ed into the Raspberry Pi and uploaded all the recent project files I posted from Spain.
Found the battery backup LiPo was fried. Bad idea to use one as a battery backup / UPS. Perhaps I am unlucky this Friday the 13th  

Pointed www.sm0vpo.com to the new IP address. While I was away the painters disconnected it for so long I had to point www.sm0vpo.com to the www.altervista.org mirror site because I lost my IP address.

Anyway, problem solved.

New project; do you remember these old Maxi-Q coils, taken over by Denco (Clacton) in the 60s?



I have been searching the web for them and absolutely impossibe to buy a set. I found isolated examples for as much as US$55 on E-bay. My pockets are not that deep. That's more than I paid for the oscilloscope CRT!!

So I took 3D-Studio Max and created something similar. Only 10mm Diameter (not 15mm (5/8")) as the originals. I also reverse-engineered some of the Denco coils and recalculated them for 10mm. Tests showed them to be surprisingly accurate. Also used 0.1" PCB matrix, instead of B9A or octal bases. I even added (optional) connection busses, just as they used in the old valve (tube) IF cans. They were aleays wonderful for mounting other components.

The project is 3D Printed Denco Substitute, uploaded this evening. I even added calculators so you can calculate your own coils. My experimental 15 MHz just happened to be within 200kHz of the calculated frequency, and was almost spot-on the 2nd Harry's Law (20 metres = 20 turns + 20pf).

Have also included the 3D-Max file, the STL file, and the printer GCODE file.

Today many people have 3D printers, and the printout doesn't take all that long, so you can always ask a friend. I borrowed one for a few months, but now I have my own. If you don't have a friend with a 3D printer, then you can buy a Wanhao Duplicator chassis for about 90$, get stepper motors from the council electronic dump site, and the SW runs on an Arduino. The motor driver card you can get from China for $30. I have used a "tea-light" under the build plate to start a printout, then when it has stuck to the plate, blow out the candle.

Hope you have fun with the project

BR Harry