VOGONS


First post, by spark2k06

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My name is Aitor and I would like to show you the following hardware design that I have published in Hackaday.io and I have available for sale in Tindie, both the kit version and full assembled. The goal is to simulate a monochrome monitor from a VGA signal in color, both in televisions and PC monitors, etc. as long as you have that input, everything from passive components, therefore, without additional power supply:

https://hackaday.io/project/166041-monochromevga

As you can see, I have also published the scheme so that anyone can create theirs if they wish, but from their own PCB design. I will be happy to answer any questions about this project, I think I have chosen the appropriate section in this forum to publish it.

https://www.tindie.com/stores/spark2k06/
https://hackaday.io/spark2k06

Reply 1 of 30, by Grzyb

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"The luminance is calculated passively and approximately to the following formula: 0.2126*R + 0.7152*G + 0.0722*B"

However, to quote some VGA chipset datasheet:

"With gray-summing flag set, BIOS will weight three color elements (RGB) of Color Register; and sum them to grayshade value, which is based on the formula (30% Red + 59% Green + 11% Blue)."

So, these I consider the proper RGB weights for VGA.

Reply 2 of 30, by spark2k06

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However, an approximate value you will be obtained with the corresponding resistors too. From these values, in a first prototype with a proto-board, I was testing with 3 variable resistors until finding the values ​​that looked best on the monitor, the result you can see in the video that I posted on youtube:

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

Last edited by spark2k06 on 2019-07-01, 12:03. Edited 1 time in total.

https://www.tindie.com/stores/spark2k06/
https://hackaday.io/spark2k06

Reply 3 of 30, by Grzyb

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Come to think of it, I saw a similar thing back in the era...
Some guy had a VGA monochrome monitor which only paid attention to the Green component of the input signal.
So, red and blue objects were totally invisible.
In order to fix that, he implemented grayscale weighting using some resistors.
However, it wasn't perfect - there were some visible distortions, probably because the resistors broke the impedance matching.
But it seems you somehow managed to avoid any distortions... so, good work!

Reply 4 of 30, by spark2k06

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Thanks!

I do not see any distortion in the image, what does happen, especially in B & W and Ambar, is a slight decrease in intensity, but it can be solved by raising the brightness of the monitor 😀

https://www.tindie.com/stores/spark2k06/
https://hackaday.io/spark2k06

Reply 5 of 30, by retardware

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Operating this unshielded is like operating broadcasting equipment.
Might cause costly problems if people (not only radio amateurs!) feel annoyed by the noise being aired.

Reply 6 of 30, by spark2k06

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retardware wrote:

Operating this unshielded is like operating broadcasting equipment.
Might cause costly problems if people (not only radio amateurs!) feel annoyed by the noise being aired.

As I said, no type of noise or distortion is appreciated.
The operation is totally normal, at least visually.

https://www.tindie.com/stores/spark2k06/
https://hackaday.io/spark2k06

Reply 7 of 30, by dionb

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spark2k06 wrote:
retardware wrote:

Operating this unshielded is like operating broadcasting equipment.
Might cause costly problems if people (not only radio amateurs!) feel annoyed by the noise being aired.

As I said, no type of noise or distortion is appreciated.
The operation is totally normal, at least visually.

That's not what retardware is talking about. Every unshielded conductor with an HF signal on it, works as an antenna. It can receive interference, but it also broadcasts whatever signal is conducted over it. Other devices may pick up that signal and be disrupted by it. Because of that, almost every country on earth has regulations about what you may and may not transmit without a license, and penalties for breaking those regulations. The kind of signals going over a VGA connector are almost certainly not allowed and IF someone is disturbed by it and IF your local regulator operates a 'fine first, ask questions later' policy.

Now, how realistic that scenario is depends totally on where you live. Here in NL, you get a friendly visit first, then a letter and only after that do fines come into view. However in DE (and iirc UK and US as well) it's not quite so friendly.

Anyway, you avoid all that stuff by ensuring this device is inside a shielded container, which can be as simple as a cardboard box lined with aluminium foil.

Reply 8 of 30, by spark2k06

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Okay, now I understand. Thank you very much for the advice, I will keep it in mind for future editions.

dionb wrote:
That's not what retardware is talking about. Every unshielded conductor with an HF signal on it, works as an antenna. It can rec […]
Show full quote
spark2k06 wrote:
retardware wrote:

Operating this unshielded is like operating broadcasting equipment.
Might cause costly problems if people (not only radio amateurs!) feel annoyed by the noise being aired.

As I said, no type of noise or distortion is appreciated.
The operation is totally normal, at least visually.

That's not what retardware is talking about. Every unshielded conductor with an HF signal on it, works as an antenna. It can receive interference, but it also broadcasts whatever signal is conducted over it. Other devices may pick up that signal and be disrupted by it. Because of that, almost every country on earth has regulations about what you may and may not transmit without a license, and penalties for breaking those regulations. The kind of signals going over a VGA connector are almost certainly not allowed and IF someone is disturbed by it and IF your local regulator operates a 'fine first, ask questions later' policy.

Now, how realistic that scenario is depends totally on where you live. Here in NL, you get a friendly visit first, then a letter and only after that do fines come into view. However in DE (and iirc UK and US as well) it's not quite so friendly.

Anyway, you avoid all that stuff by ensuring this device is inside a shielded container, which can be as simple as a cardboard box lined with aluminium foil.

https://www.tindie.com/stores/spark2k06/
https://hackaday.io/spark2k06

Reply 9 of 30, by spark2k06

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I added a warning in the Tindie ad and in the hackaday article:

"Disclaimer:

It is recommended to use this device inside an shielded container, which can be as simple as a cardboard box lined with aluminium foil, because although unlikely, the VGA signal could interfere with other nearby devices and depending on the laws of your country, it could lead to fines.

Therefore, USE IT AT YOUR OWN RISK."

Likewise, I will notify those who have already acquired me one or several units.

Again, thanks @dionb and @retardware for the advice 😉

https://www.tindie.com/stores/spark2k06/
https://hackaday.io/spark2k06

Reply 10 of 30, by spark2k06

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Now discounted for the latest units of the PRO version:

https://www.tindie.com/products/spark2k06/monochromevga-pro/

and back in stock of Basic version, with improvements over the previous batch:

https://www.tindie.com/products/spark2k06/monochromevga/

https://www.tindie.com/stores/spark2k06/
https://hackaday.io/spark2k06

Reply 11 of 30, by Badscrew

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Hi, interesting project!

I have a question: for the regular (non-PRO) version, which one will give the best Amber output, the one with the diodes or the one without?

Reply 12 of 30, by spark2k06

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Badscrew wrote:

Hi, interesting project!

I have a question: for the regular (non-PRO) version, which one will give the best Amber output, the one with the diodes or the one without?

The one with no diodes, but with the drawback that the color change with the switch is not good.

However, the effect of the diodes in that case is only a loss (not excessive) of brightness, but you can always adjust the brightness and contrast of the monitor.

https://www.tindie.com/stores/spark2k06/
https://hackaday.io/spark2k06

Reply 14 of 30, by spark2k06

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Badscrew wrote:

What do you mean by color change?

The board has a switch to change color to monochrome and vice versa.

https://www.tindie.com/stores/spark2k06/
https://hackaday.io/spark2k06

Reply 15 of 30, by Badscrew

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Yes, I mean what isn't good in the "no-diodes" case?

Edit: I want to buy one, just need to decide which one 😀
Particularly interested by amber output (I love the old amber monitors)

Reply 16 of 30, by spark2k06

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personally, the option with diodes I think is the best option. And if your amber output does not convince you, you can always short-circuit the diodes. In any case, I hope you like the result, you will tell us! 😀

https://www.tindie.com/stores/spark2k06/
https://hackaday.io/spark2k06

Reply 17 of 30, by Jo22

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This thread reminds me of WinGIF. It had an option for users of monochrome VGA monitors.
By using the standard 640x480x16c VGA driver, it was able to produce pretty grayscale pictures using false colours.

"Time, it seems, doesn't flow. For some it's fast, for some it's slow.
In what to one race is no time at all, another race can rise and fall..." - The Minstrel

//My video channel//

Reply 19 of 30, by spark2k06

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nali wrote:

I like this !
I would be curious to see a modern OS or 3Dgame running this way 😀

It's a good idea, I don't have a very modern PC, but if someone has it it might be interesting to see a demo in amber mode, for example. But you can see an example of what Ghost And Goblins looks like, with the first prototype I made based on protoboard: 😊

https://www.youtube.com/watch?v=9xwnpiCaRJE

https://www.tindie.com/stores/spark2k06/
https://hackaday.io/spark2k06