I Need Help

[Fyvve]

Please look at the diagram on this page about a quarter of the way down.Link

So in that diagram i am not sure how to read the diode part. I think it is saying to put the diode in with the line on the diode closest to the DB9 side. i.e.


Diode with the line on the left side


DB9 Pins ----<-|-------------->----- DB25 Pins

Is that correct? I know that the "arrow" of the diode points in the opposite direction of flow but i am not sure what that means when translated to the actual diode. Thanks in advance.

Edit: my drawing was crap

 

[refractor]

I think it is saying to put the diode in with the line on the diode closest to the DB9 side.

Correct. The line marks the cathode. In the circuit diagram, the line after the triangle is the cathode.

Anode ------|>|----- cathode

The arrow points in the direction of the travel.

 

[Fyvve]

I know that the "arrow" of the diode points in the opposite direction of flow but i am not sure what that means when translated to the actual diode. Thanks in advance.

So i guess i was wrong then on the part about the direction of flow? The arrow actually points in the direction of flow. Just for clarity's sake: in the diagram i linked to, current can flow from the DB25 pins to the DB9 pins but not the reverse of that...? Which means i would put the lined end of the diode closer to the db9 side...?

I hope that is right because thats the way it makes sense to me. If its wrong then i am totally lost.

 

[gp32rich]

I know that the "arrow" of the diode points in the opposite direction of flow but i am not sure what that means when translated to the actual diode. Thanks in advance.

It's a historical assumption that current flows from positive to negative.
It was later found that electrons carry negative charge, so current flows in the opposite direction.
Thay had a 50-50 chance of getting it right - and they guessed wrong

Diodes were created before this was discovered and the diagram does point in the direction of 'classical' current flow, positive to negative.
This kinda describes what they do, but it's opposite to how they do it.
TBH It always confused me.

But things are simpler when you're not designing the circuit
When you get a physical diode it is marked with a bar at or near one end. This matches the bar on the diagram so you should have no trouble matching them up.


[edit] after googling :S

 

[WarmFluffyUK]

Not sure if this is of help, but I have drawn a little image of a diode and included a diode diagram, which shows you the relationship between the two:

Clare.

 

[Fyvve]

Thanks for the replies. It ended up not working. I dont know why. It sort of works but the d pad directions register as buttons. And only b and c work on a six button controller. And b and c both show that you are pressing two buttons when only one is pressed. Very frustrating. I spent 40 bucks on the supplies for this. damn....