A lot of people were wondering exactly what testing I did to come to the conclusions from the other post. That’s a great question! Here’s what I did that proves out the math from the other article. Feel free to reference it when you’re double-checking the findings.
My first article on this subject was intentionally written for a non-technical audience. We purposely simplified some of the models, opting for an ideal representation instead of a practical one, in order to produce a message that was accessible to all. Seems like some part of the internet was not happy with that. Therefore, in this video I describe exactly what the clamping diode effect is, measure it on the oscilloscope, show when it happens, and why it’s not such a great idea to design a circuit that does this.
The video starts off with a theoretical explanation, followed by a practical example of the effect at 6:05. The practical example shows the clamping diode effect being measured on D12 of the Sega Genesis while using a Mega Everdrive.
EDIT: The normal logic high voltage of the console, when a real cartrdige was used, is 5V dead on. I’ve seen a few forum posts today that “theorized” the actual console’s output was always closer to 4.6V regardless of what device is connected in the cartridge port.