simon.plata

Hi, Here is a schematic and PCB design for the mod made in Eagle CAD. I will fabricate it to replace my generic PCB. If someone want to fabricate your own PCB, just let me know. I can share the PDF or the Eagle files.

Hi, Nice work, I'm pleased it worked for you, moreover considering it was done on a PAL which requires a higher bandwidth. Best regards,

Do you mean V1 and V2? They are voltaje sources to model the Atari's +5 volts power suply (V2) and the video signal (V1). But you don't need to worry about them, just ignore them because are just for simulation purposes in LTSpice.

Good question, I was asking to me the same thing. I did some experiments and I found the resulting video is too Sharp. Even each pixel could be seen. This makes some text dificult to see, also camera is 50% guilty. I added some distortion to the signal to make it more blurry and then it is easier to read. I take some pictures, first is the clean output: This is with some added blur (distortion) and different camera settings: If you prefer to add some distortion, just add a capacitor (from 47pF up to 100pF) between pin 4 (video signal from the Atari) and GND.

Great! One sugestion, I selected the resistor values to be easy to find in 1% metal film precisionn or in 5% carbón film. If you decide to use 5% tolerance components, just buy at least 5 of each and read the value with a multimeter and use the most close to the design value. Large deviation in the resistors values could affect the results because it is DC coupled. Also try to test the transistors and use the ones with the higher gain.

Just sharing a picture of SeaQuest in a CRT TV using composite video!

Hi, I'm glad you want to give it a try. I forget to indicate it is for NTSC signal bandwidth and may be not perform well on PAL. The capacitor was tougth to increase the gain at high frequency and reduce the phase shift of the color signal. A 47pF capacitor gives a Little more crisp to the colors but it's not much noticiable, then I decided to not use it to keep the mod as simpleas possible. The Brown wire is for the audio signal. This signal does not need additional amplification, then I just put a 100 Ohm resistor to ease the connection. The signal is taken from the node indicated by the red arrow. Attached some pictures for clarification. Hope it Works good for your. Please share your results and don't hesitate to ask any other questions you have.

It looks like the LED TV processing trow away or filter some pixels in some frames. Only the camera notice this, but is less noticiable when looking directly with your eyes. My conclusion is definitively is the LED TV processing, because this is not happening in the CRT TV.

I had the same problem but I solved it with this simple DIY AV mod: http://atariage.com/forums/topic/271678-simple-diy-composite-video-mod/ CRT TV image LED TV image

Hi, I tried some simple composite video mods for my Atari 2600 with terrible results: Blurry image, ghosting, dark image, etc. Then I designed my own mod and it works good enough for me. I wanted to share it with all who want to give a try. First you need to remove some components from the board. I prefer to remove all unused components and store them. But if you are more conservative then remove the following components only Also, you need to remove or disconnect the "RF Modulator Module" and built the Video Amplifier. I designed two simple video amplifiers: The first is a simple one stage amplifier. This circuit Works good but due to the limited gain of only one amplification stage, there is some limitation in the brightness of the image. Most people will not notice it, but I wanted to ensure the best quality possible keeping it simple. The second is a two stage amplifier. This is still a very simple circuit with flat gain up to 4.2MHz (Composite video band width) which ensures brightness and color preservation with minimun distortion. Use the 5K trimmer to adjust the gain (brigthness) of the signal. Teorically you will have 0dB or unity gain with 1577Ohm. This is the Bode plot of my LTSpice simulation of the circuit This is the board with the circuit installed And finally this is the results: Video on a CRT TV Video on a LED TV

Hi, I tried some AV mods from internet in my Vader board with terrible results, blurry image, dark, etc. Then I designed my own transistor video amplifier mod an the results are good for me. First image is in a CRT TV and the second is a LED TV. Very simple and cheap DIY circuit.

I had same problem with my AV mod. The problem was the coupling impedance and a 150pF capacitor not removed from the board. I decided to design my own video amplifier and it Works well. First I tried with a simple one stage design. Clear and Sharp image but not ful brightness. Then I tried with a two stage and I'm happy with the results. Attached the scree pictures of an CRT TV and a LED TV. If you are interested in try this circuit just let me know and I will post the schematics.