Smart Sockets for Telefunken ZM 1350

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1 month 2 weeks ago - 1 month 2 weeks ago #10478 by Torsten Lang
Hi,
some months ago I designed my own interpretation of so called "smart sockets" for the rare Telefunken alphanumeric nixies ZM1350.

Yesterday and today I finally found a window to occupy our pick'n'place machine and the reflow oven. So finally I could assemble the PCBs. Here are some pictures:





As you can see the socket uses a modern 32 bit Cortex M0 controller. I cleanly separated the high tube supply voltage from all low voltage signals and supply on the connector. And I furthermore took care to expose the high voltage as less as possible and to protect all low voltage supply and data lines. No place for a sloppy design here as 170V are potentially lethal.

In contrast to other designs I route more lines to the connector to get more flexibility. So I have the possibility to use UART or I2C and have a general purpose line (e. g. as a trigger). I also provided some solder jumpers in case I don't implement any auto detection scheme.

The next step is to design the main controller board which also will contain the high voltage power supply.

I'm not yet sure if I design a high voltage supply my own. If anyone knows a reliable and high quality ready to use supply please let me know. I would prefer a ready-to-use solution for a lot size 1 project. What I need worst case is about 16mA/socket, I plan to use 10..12 sockets. So the power supply should be able to deliver 200mA minimum.

Regards,
Torsten

P. S. I don't known why the forum software rotated the first foto (I checked the copy on my server - it is clearly upright)...
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Last edit: 1 month 2 weeks ago by Torsten Lang.

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1 month 2 weeks ago #10480 by Ty_Eeberfest
That looks VERY nice! I am envious. :)

It has been a few years since I looked for a ready-to-use HV power supply. I never found one that would drive more than 50mA, which is nowhere close to what you say you are looking for. When I needed almost 500mA for my "shoutbox" project I ended up using a brute force approach: isolation transformer, bridge rectifier, big capacitor. Definitely not elegant or efficient but it sure does work! B) I'm in a 120V country so a simple 1:1 transformer was all I needed to end up with 169Vdc output. If there are any wobbles in the DC due to mains fluctuations they are too small to see on the tubes.

Look into it later when the dust is clearing off the crater.

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1 month 2 weeks ago - 1 month 2 weeks ago #10481 by Torsten Lang
Hello Ty,
I had similar feelings when I saw the feature about your shoutbox ;)

That feature inspired me to go on with my smart socket although I'm quite disappointed with the situation with my VFD clock that currently binds a lot of money. This is why I didn't even think about making these smart sockets available to the public.

I'm not yet sure how to solve the power supply problem. Taking mains power directly is not really an option - things have changed a lot over the last two to three decades when it comes to regulations. Today most low voltage applications are powered by some kind of wall wart delivering an intermediate DC voltage.

If suppling from mains there would be a quite simple solution similar to yours: I found the idea to connect a 220V/9V and a 220V/15V transformer together on their secondary side to generate about 130V AC. For todays higher mains voltage that would have to be adapted a bit but transformers with 130V output are simply not available.

If I have to design a PSU myself I think I will go for a flyback converter which clearly is the superior solution compared to a 12V to 170V boost converter.

Regards,
Torsten
Last edit: 1 month 2 weeks ago by Torsten Lang.

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3 weeks 2 days ago #10567 by Ian
Nice work!

I'm also totally envious that you have a pick and place machine and a reflow oven. I have soooo many projects that I have on the list and hand prototyping is really slow.

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3 weeks 2 days ago #10572 by Torsten Lang
Yes, I'm really happy that I can use our equipment for such projects. A major problem with SMD are the stencils. We have a paste printer, but the stencils for this are quite large which makes the shipping expensive (for my clock project shipping alone was nearly 100€!).

Regards,
Torsten

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14 hours 49 minutes ago - 14 hours 49 minutes ago #10615 by Torsten Lang
Hi,
regarding the power supply I found a preliminary solution: On Amazon currently there are boost converters for up to 40W (70W peak) output power available. They are made for 8V..32V input (instead of the more common 9V..36V) and can be adjusted for 45V..390V output. Regarding EMI I do not expect too much because it's a two layer PCB with a quite dilettante layout. It seems to be a flyback design.

Nevertheless I think it's a simple start to get my smart sockets into operation...

Regards,
Torsten
Last edit: 14 hours 49 minutes ago by Torsten Lang.

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