Closed C128 CGA to RGB adapter

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Pyrofer

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Update - Please place all purchases through my webshop at,
http://www.pyrofersprojects.com/blog/shop

I will leave this thread open for now so people can ask questions about the device/installation etc and share their installation photos. There should probably be a proper place for that and any suggestions are welcome as to where!
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I have been making and selling these in small numbers. I just improved my PCB and wanted to judge interest in how many more I could sell.
Details,
All Digital processing stage using a programmable logic chip (GAL). This means that there is no loss of quality by mixing signals, also the brown fix is done in logic providing the correct output of brown and yellow instead of 2 yellows.
6bit DAC output. Each of the output channels, R,G,B is output as 2bits and goes into 2 resistors. There is no "Pull up" or "Pull down" mixing the intensity signal across channels. It's a simple 6bit RGB DAC for the best quality no bleed picture.
Correctly mixed Composite sync. A very reliable sync signal by using the 'correct' logic for mixing H and V sync inputs.

9pin CGA plug onboard. Simply plug it directly into the back of the C128, no 9pin cable needed.
15pin RGB output onboard. It uses a VGA style connector so monitors that support 15khz can plug directly in to it. So called "CGA to VGA" adapters like the Gonbes board also have an input that uses the VGA connector, Somebody tested this and the adapter works fine with the gonbes and a straight VGA cable. The standard VGA pinout is used with composite sync on H sync pin. Pin 9 carries 5v for use in SCART (euro) connector cables that trigger the fast blanking pin to put the display into RGB mode.
S-Video connector onboard. The signals from the VIC can be passed through this board via a pin header to allow the use of standard S-Video cables.
3.5mm Audio Jack onboard. As with the VIC video signals the audio signal can be accessed easily with a stanard 3.5mm jack.
6pin header for VIC DIN connector (not supplied). As the board needs 5v and the 128 supplies 5v via the video DIN output I put a 6 pin header on with inputs for, Ground, 5v, Audio, Composite (not connected), Chroma and Luma (Fed to the S-Vid connector). This allows for a very neat installation with this board plugged directly into the 128 and a single cable to the video DIN plug for all other signals. Output is then out via the VGA plug and S-Video plug for 80 and 40 columns.

I can't overstate the difference of using a logic system to convert the 4bit input to 6bit output. The high speed GAL used produces an amazing quality output that you really have to see and compare to a lot of other DIY solutions to understand.

14055122_10157320219885608_2838891942733823945_n.jpg14054974_10157320487930608_7381928756297242619_n.jpgpluggedin.jpg14466885_10202110583123716_1812842163_o.jpg
1) The adapter 2)My testcard image 3)how it connects 4) a customer running it through a gonbes adapter.

The price is £30+post. I have been posting internationally but currently have no stock as I hand assemble them. Please register your interest here.
UPDATE - Price is £40+post due to an increase in parts costs and assembly difficulty - Apologies for this.

*The din cable shown cannot be provided as I don't have a source for the plugs. It is up to the buyer to provide a connection between the video out and the pin header. To use 80 col only you simply need 5v on pin2 which can come from the user/tape or video ports.

Tested direct to a SCART TV, working fine.
Tested direct to a gonbes VGA adapter (using a normal VGA cable) and works fine.
Tested with a cheap SCART to HDMI adapter from eBay, works fine.
Should in theory work with any normal RGB monitor such as used on Amiga.
 
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Count me in, though could be a month or so before I can afford it so only accept me of that's okay with you!
 
this would work with a CGA signal from a PC right? It is the better equivalent of this, correct?



I have built the one above and it works fine with pc/cga , if the adapter on sale is also the same function-wise I'd like one as well
 
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Yes, it's a similar function to that circuit but done with a true 2 bit per colour output for the DAC for a better picture.
It takes RGBIHV in and does RGBs out. I see no reason it wouldn't work with PC CGA cards.

I would love to see somebody using it on an original CGA card on their PC :) photos must be provided !
 
Hi i want one too, to use with an IBM XT clone with a true CGA card.

EDIT: Need more clarification on this.

I understood that the board can be powered via a DIN connector on the C128, but since i want to use this with IBM CGA i would i power the board?

Additionally, the VGA connector is useless for me, since i don't have any VGA monitors capable of syncing to 15KHz, i want to use the SCART connector on my Trinitron CRT TV. AFAIK, unless the TV set supports it, S-Video to SCART won't work since it was never part of its specification.

I just need to understand how i would make this work for IBM CGA.
 
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Assembly takes time, making the SCART cable would dramatically increase the cost for both parts and assembly.
You can get VGA to SCART plugs on eBay but I have not bought one to check the pinout yet.
I made mine by simply cutting one end off a normal VGA cable and soldering the wires to a SCART plug.
 
Assembly takes time, making the SCART cable would dramatically increase the cost for both parts and assembly.
You can get VGA to SCART plugs on eBay but I have not bought one to check the pinout yet.
I made mine by simply cutting one end off a normal VGA cable and soldering the wires to a SCART plug.

So i'd be using the VGA connector to SCART? That's fine with me, but i can i power the board? Do i have to power it exclusively via those pin headers?
 
the Pin header (pin2) and pin 9 of the VGA port both connect to the 5v line on the chip.
I use pin 9 on the VGA plug to connect to the fast blanking pin on the SCART to ensure the display switches into RGB mode.

When used with the C128 the Video out DIN carries the S-video, audio and 5v which all connect to the 6 pin header. If not using with a 128 this is not needed (and the S-Video socket will serve no purpose).

You would simply need to put 5v onto pin 2 of the pin header.

If your TV allows for forcing RGB mode on the SCART (some do, some don't) then you don't need to worry about pin 9 being connected to fast blanking either.

I hope this clarifies what you want.
 
the Pin header (pin2) and pin 9 of the VGA port both connect to the 5v line on the chip.
I use pin 9 on the VGA plug to connect to the fast blanking pin on the SCART to ensure the display switches into RGB mode.

When used with the C128 the Video out DIN carries the S-video, audio and 5v which all connect to the 6 pin header. If not using with a 128 this is not needed (and the S-Video socket will serve no purpose).

You would simply need to put 5v onto pin 2 of the pin header.

If your TV allows for forcing RGB mode on the SCART (some do, some don't) then you don't need to worry about pin 9 being connected to fast blanking either.

I hope this clarifies what you want.


Thanks, that helps.

All i need to do is to get the proper cables and to run 5V either from an external source or from the PC insides.

I am still interested in one adapter so count me in please.
 
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