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Bryan

New video upgrade coming soon!

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I see you are from Austria. You got PAL B/G there, same as Italy, right ??

Any Atari 400 PAL computer ever produced outputs from factory a PAL-I (UK, Ireland, Hong Kong, South Africa, and Macau) RF signal... (afaik).

This lead to a problem when we try to RF tune the output of a PAL-I (UK) on a standard PAL B/G TV set (Italy, Austria, most of Western Europe, Australia, and New Zealand).

The video part is tuned with no problem, but the audio is "%&/%$/%£&/%$/&&/£%"£%$"%£&/$"£####" (you get the point, right?).

Is this the same reason why you want to install a UAV board in your 400 ?? You have the same issue on your 400 ??

Let me know your thoughts.
 
C.

The last time I played a 400 via RF was about 30 years ago ;) I never had one back in the 80s and my friend soon upgraded to an 800XL. I now have an NTSC 400 which I want to install the video mod in and an acquaintance needs the mod installed in a PAL machine. Once Bryan has posted his instructions for 400 sound that should take care of poor sound quality.
Sorry for not reacting sooner, didn't notice that post in the torrent that thread has become.

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Thanks man.

Could you share pictures of the actual mod kit you received?

I was not able to fetch one in time unfortunately.

So i need to wait for the next batch. Edited by iratasan

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The last time I played a 400 via RF was about 30 years ago ;) I never had one back in the 80s and my friend soon upgraded to an 800XL. I now have an NTSC 400 which I want to install the video mod in and an acquaintance needs the mod installed in a PAL machine. Once Bryan has posted his instructions for 400 sound that should take care of poor sound quality.
Sorry for not reacting sooner, didn't notice that post in the torrent that thread has become.

There's no need for Bryan to come up with instructions for an audio upgrade, these already exist from other sources.

 

First of all, do you plan on keeping the RF output once the UAV is installed?

 

If not the audio could be disconnected from the video(remove R164), and the sound oscillator disabled(removed C177,C178,R162). The pad for R164 connected to C183 can then be used for the audio source, if audio signal is too strong insert resistor of required value in path to output jack, if too weak reduce values of R161,R166 as necessary.

[attachment=445116:400_2.jpeg]

 

If RF output is being retained the following is the suggested audio circuit from the Little Brother Grows Up article(April 1984 ANTIC)

[attachment=445117:LBGU-audio.jpg]

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There's no need for Bryan to come up with instructions for an audio upgrade, these already exist from other sources.
 
First of all, do you plan on keeping the RF output once the UAV is installed?
 


Thanks for the Vector. Do you happen to know whether these include SIO sound as well?

(I would not keep NTSC RF, with PAL I'm not sure.)

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If RF output is being retained the following is the suggested audio circuit from the Little Brother Grows Up article(April 1984 ANTIC)

attachicon.gifLBGU-audio.jpg

 

I've got someone testing something similar to this, but with fewer parts. For example, you don't really need the caps for DC blocking on both the inputs and outputs.

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Thanks for the Vector. Do you happen to know whether these include SIO sound as well?

(I would not keep NTSC RF, with PAL I'm not sure.)

Both of these include SIO audio, the Little Brother Grows up schematic calls it tape audio. Their relative volumes may be different with the LBGU version as it takes the 2 signals from different locations before they combine, I think this is to weaken the sound oscillator carrier signal.

 

My suggested modifications to the original circuit if not retaining RF output isolates the video signal from the audio and disables the sound oscillator carrier signal used by the RF modulator.

 

Personally, with the UAV for video output, I see no need to retain the RF signal. There is no need to remove the RF modulator completely, removing L203 on the power board will disable it.

 

If you are retaining RF output I would suggest using a chassis mount RCA jack or a short RF cable with inline RCA jack, so the long RF cable no longer needs to be permanently attached.

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This is what I'm proposing for a simple 400 audio mod:

 

msg-3606-0-93755200-1460246102.jpg

 

The 47K/18K input resistors have roughly the same 2.6:1 mixing ratio as the 18K/6.8K resistors in the RF mixing circuit. The mixed signal is always within the 0-5V range so I don't use any input capacitors. The opamp is configured as a follower to make the circuit as simple as possible. It can be configured for gain if you wish using feedback resistors. The output is capacitor coupled, removing the DC offset (4.7uF gives a cutoff frequency of 7Hz into a 5Kohm load). Power/ground for the opamp can be pulled from both sides of C182.

 

Thanks to orpheuswaking for testing this for me.

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This is what I'm proposing for a simple 400 audio mod:

 

msg-3606-0-93755200-1460246102.jpg

 

The 47K/18K input resistors have roughly the same 2.6:1 mixing ratio as the 18K/6.8K resistors in the RF mixing circuit. The mixed signal is always within the 0-5V range so I don't use any input capacitors. The opamp is configured as a follower to make the circuit as simple as possible. It can be configured for gain if you wish using feedback resistors. The output is capacitor coupled, removing the DC offset (4.7uF gives a cutoff frequency of 7Hz into a 5Kohm load). Power/ground for the opamp can be pulled from both sides of C182.

 

Thanks to orpheuswaking for testing this for me.

 

No problem, sorry to anyone in the thread waiting for this as it took me longer than I expected to get this tested out. 

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Thanks for the effort of designing and testing this to Bryan and orpheuswaking! Being quite electronically challenged, I have tried to kind of combine the two pictures into something I hope to be able to recreate on a perf board. (I actually tried to design a PCB with Upverter but as I have never done that before I failed in finding the correct sizes for the parts and therefore put holes and traces in the right places.) 

 

It would be great if you could confirm that I got the connections to the amplifier right.

 

Thanks!

 

[attachment=445436:Atari-400-Audio-out--3.png]

 

Is it OK to take the ground for the audio cable right from Vdd or should it better come from the same place as the ground for the video signal?

 

 

 

 

 

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Looks correct, 

 

PIN 1 NC

PIN 2 connect to PIN 6. This connection also goes to the 150 ohm resistor and the 4.7uF cap (positive toward the opamp, other end to the amplifier).

PIN 3 this is the positive input to the opamp. The other two resistors connect here.

PIN 4 is ground.

PIN 5 NC

PIN 7 is 5V

PIN 8 NC

 

Bryan isn't planning to make boards for this as it's just for a single machine. However I've discussed with him about getting a small amount made myself and he is assisting me with that. No promises or timeline (But won't be too far in the future)... Not sure if I will offer them as a kit or If I will solder them myself (Caveat I'm not the best at that but I will guarantee it will work.)

 

The one I made on prototype board works but I think a small board would be neater to put in along with the UAV board (I just have problem with that neat board and then my ugly audio mod.)

Edited by orpheuswaking

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However I've discussed with him about getting a small amount made myself and he is assisting me with that. No promises or timeline (But won't be too far in the future)... Not sure if I will offer them as a kit or If I will solder them myself (Caveat I'm not the best at that but I will guarantee it will work.)

 

The one I made on prototype board works but I think a small board would be neater to put in along with the UAV board (I just have problem with that neat board and then my ugly audio mod.)

 

That would be great! I'd take two of them assembled or unassembled.

 

I was concerned about aesthetics as well but quickly found that I lack the skills to create a small board (and the time to acquire the skills).  

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That would be great! I'd take two of them assembled or unassembled.

 

I was concerned about aesthetics as well but quickly found that I lack the skills to create a small board (and the time to acquire the skills).  

 

Nah, I'm sure you are about as handy as I am, just takes time and patience... I almost just made it as a "dead bug" install to test it. 

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Finally got around to installing the uav in an 800xl.   This is the basic board so I ordered some breakable header pins strips from china, think 1 dollar free shipping or something.  I took the opportunity to remove the rf modulator and I removed the 4050 as well.

 

I really cant believe how fantastic the picture is now, its pretty much perfect.   This is on a Vizio 24" led tv.   Monitor port to s-video to hdmi.    Kudos Bryan.  

 

 

[attachment=446598:20160417_194459_resized.jpg]

 

[attachment=446599:20160417_194511_resized.jpg]

 

[attachment=446600:20160417_194540_resized.jpg]

 

 

Edited by bugs

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Finally got around to installing the uav in an 800xl.   This is the basic board so I ordered some breakable header pins strips from china, think 1 dollar free shipping or something.  I took the opportunity to remove the rf modulator and I removed the 4050 as well.

 

I really cant believe how fantastic the picture is now, its pretty much perfect.   This is on a Vizio 24" led tv.   Monitor port to s-video to hdmi.    Kudos Bryan.  

Nice install! What device are you using to convert to HDMI?

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Im using the StarTech composite/s-video to hdmi converter

 

http://www.walmart.com/ip/StarTech-Composite-and-S-Video-to-HDMI-Converter-with-Audio/29503170

 

I am going to try some cheaper ebay solutions, be nice to find one that can fit inside the Atari.

 

I have a full uav left and I cant decide which machine deserves it the most lol.  I will order a few more when they get in the store.

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Bryan is going to have hire an army of Costa Rican solderers to make all the boards needed lol.


Sent from my SM-G920W8 using Tapatalk

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I'd like one of the 400 audio mod boards as well.

 

Thanks!

 

 

Looks correct, 

 

PIN 1 NC

PIN 2 connect to PIN 6. This connection also goes to the 150 ohm resistor and the 4.7uF cap (positive toward the opamp, other end to the amplifier).

PIN 3 this is the positive input to the opamp. The other two resistors connect here.

PIN 4 is ground.

PIN 5 NC

PIN 7 is 5V

PIN 8 NC

 

Bryan isn't planning to make boards for this as it's just for a single machine. However I've discussed with him about getting a small amount made myself and he is assisting me with that. No promises or timeline (But won't be too far in the future)... Not sure if I will offer them as a kit or If I will solder them myself (Caveat I'm not the best at that but I will guarantee it will work.)

 

The one I made on prototype board works but I think a small board would be neater to put in along with the UAV board (I just have problem with that neat board and then my ugly audio mod.)

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