u/ik_pieta

Hi! I just received my QMTECH Mister but I'm having trouble getting a stable output. I'm using this ArcadeXpress Cable and i have the USB cable hooked up to 5V. In my Mister.ini i have composite_sync=1 and vga_mode=rgb. Thank you all so much!

UPDATE: I finally got it to work! It turns out the sync voltage might’ve been too low for my particular CRT. Inside the ArcadeXpress cable, there’s a 1k ohm resistor between the sync signal and SCART pin 20. For a quick test I removed it completely and boom: I got a stable and normal image on my CRT!

HOWEVER it has been brought to my attention that completely leaving out the resistor is potentially harmful to the CRT. The VGA port on the MiSTer “outputs sync at 3.3vp_p (point to point)” which is way too high for what a TV usually expects. As user u/Medic8ted told me:

>TV wants at least 0.3v (actually 0.286 iirc, but we tend to round up), though up to even ~1v is "safe".

>[..] We should lower that 3.3vp_p sync voltage to be safe. I think you should be good to replace that 1K with a smaller value, such as ~330, 470, 510, 560, 620 ohms. That will still give you a sync around 0.3 - 0.6 vp_p which is fine.

>What would I choose? 470 ohms... or any of the ones I've listed already.

So I would highly recommend replacing the current resistor with a 470 ohm resistor to keep the sync signal at a safe level for the CRT and also maximise compatibility! Thanks to everyone who helped me.

TL;DR what fixed my issues was changing out the 1k ohm resistor for a 470 ohm resistor in my VGA to SCART ArcadeXpress cable.

Hello! I have zero experience with KiCad but i do have a reasonable amount of knowledge with electronics.

Online i found an open source recreation of the Super Nintendo Entertainment System motherboard. For a project of mine I want to relocate the 62 pin cartridge slot to fit my 3d printed shell better.

My idea was to adjust the cartridge connector slot section of the opensource PCB and add two generic 1x40 pin connectors. These will then be connected via approximately 15 to 20 cm in length ribbon cables to a separate board, which will link the original motherboard to the extension / relocated cartridge slot. I chose two 1x40 pin connectors partly because I only had the corresponding 40 pin connectors and ribbon cables on hand but also because this would allow me to alternate between critical signal lines and GND lines to minimize interference.

I dont know much about KiCad so I'm currently having trouble editing all of this. I was able to add the 40 pin connector but i have no idea how to get it to show up in the pcb editor as well.

How do i achieve this? Is this even a good idea? Do I need to worry about interference with ribbon cables?

Thank you all!

Hi! In 1976 Nintendo released a light gun "Duck Hunt" game that used a lamp, lens, and moving mirror to project a duck onto a wall. I'd love to recreate one myself, since original units are very expensive.

I found the patent here and I think I understand most of the optical system, but I'm completely stuck on the mirror drive mechanism.

From what I can tell, the mirror moves both up/down and left/right using a single motor, several gears. The patent drawings I'm looking at are mainly Figures 4 and 6.

This video briefly shows the mirror mechanism in action. I understand how an eccentric cam can create up/down motion, but I don't understand how the left/right movement is generated mechanically, or how I would reproduce the entire mechanism as a beginner.

How do i recreate this?

Thank you very much!

Edit: Broken patent link has been fixed.

Hi! In 1976 Nintendo released a light gun "Duck Hunt" game that used a lamp, lens, and moving mirror to project a duck onto a wall. I'd love to recreate one myself, since original units are very expensive.

I found the patent here and I think I understand most of the optical system, but I'm completely stuck on the mirror drive mechanism.

From what I can tell, the mirror moves both up/down and left/right using a single motor, several gears. The patent drawings I'm looking at are mainly Figures 4 and 6.

This video briefly shows the mirror mechanism in action. I understand how an eccentric cam can create up/down motion, but I don't understand how the left/right movement is generated mechanically, or how I would reproduce the entire mechanism as a beginner.

How do i recreate this?

Thank you very much!

Hi! In 1976 Nintendo released a light gun "Duck Hunt" game that used a lamp, lens, and moving mirror to project a duck onto a wall. I'd love to recreate one myself, since original units are very expensive.

I found the patent here and I think I understand most of the optical system, but I'm completely stuck on the mirror drive mechanism.

From what I can tell, the mirror moves both up/down and left/right using a single motor, several gears. The patent drawings I'm looking at are mainly Figures 4 and 6.

This video briefly shows the mirror mechanism in action. I understand how an eccentric cam can create up/down motion, but I don't understand how the left/right movement is generated mechanically, or how I would reproduce the entire mechanism as a beginner.

How do i recreate this?

Thank you very much!

Edit: Broken patent link has been fixed.