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Could I fry my LedWiz if I...

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Kman-Sweden:

We'll see how long they last... I've soldered wires to the holes labeled 1 to 4 on the RGB-drive.
+5V to No:4 and GND to the others depending on desired color.

It's powered (and grounded) by another PSU than the PC.



When the "PC PSU" is turned ON, running Mame in Maximus Arcade, the LedWiz is calling all the shots.

When the "PC PSU" is OFF the "Extra PSU" powers the LED's in buttons 1-4 with constant +5V, making them light up in a predetermined colors (Red, Yellow, Green and Blue).
This is for my NeoGeo MVS... The NeoGeo is actually powered by a third PSU that only have power when the Extra PSU has power...
I'll post some pics when the project is completed.  ;D

Beley:


--- Quote from: Kman-Sweden on February 11, 2010, 04:38:14 pm ---We'll see how long they last... I've soldered wires to the holes labeled 1 to 4 on the RGB-drive.
+5V to No:4 and GND to the others depending on desired color.

It's powered (and grounded) by another PSU than the PC.



--- End quote ---

The way you have it drawn it wont work, you have shorted the 3 outputs from the led wiz together, as RandyT said you would have to put diodes in to make it work as shown (put them where you have drawn the dashed Ground lines)

Kman-Sweden:


--- Quote from: RandyT on February 11, 2010, 11:48:45 am ---An external diode to prevent backfeeding to the LED-Wiz, and maybe another on the external supply, might be prudent.

RandyT

--- End quote ---
On the +5V?

Bobulus:

I don't think diodes on the ground lines would be the way to go, but either way...wouldn't the Ground on the Extra PSU be connect whether or not the Extra PSU is turned on? (Assuming you're not unplugging it all together) That would mean, for example, that if you've got a button set to be 'red' when the computer is turned off (by connecting the RGB-drive red ground to the Extra PSU ground), that even when the computer is on, the red part of the RGB will always be on.

I'm assuming Randy was talking about diodes on the 5V lines to prevent power from going from the Extra PSU, bypassing the resistors in the RGB-drive entirely, and directly into the LedWiz, which would probably be bad.

There's probably a more elegant way to do it, but seems like what would work would be to use transistors on the ground lines to open or close them based on the power coming off the PC-PSU 5V line.

* I only took one semester of electronics. My career is in biology. These guys are almost sure to know more than me. Listen to them.

Kman-Sweden:


--- Quote from: Bobulus on February 12, 2010, 01:10:52 pm ---I don't think diodes on the ground lines would be the way to go, but either way...wouldn't the Ground on the Extra PSU be connect whether or not the Extra PSU is turned on? (Assuming you're not unplugging it all together) That would mean, for example, that if you've got a button set to be 'red' when the computer is turned off (by connecting the RGB-drive red ground to the Extra PSU ground), that even when the computer is on, the red part of the RGB will always be on.

I'm assuming Randy was talking about diodes on the 5V lines to prevent power from going from the Extra PSU, bypassing the resistors in the RGB-drive entirely, and directly into the LedWiz, which would probably be bad.

There's probably a more elegant way to do it, but seems like what would work would be to use transistors on the ground lines to open or close them based on the power coming off the PC-PSU 5V line.

* I only took one semester of electronics. My career is in biology. These guys are almost sure to know more than me. Listen to them.

--- End quote ---
I couldn't wrap my mind around the "diode on GND" either... I think I have to give his some more thought before hooking up the PC to it again...
All help would be appricated.  :-\

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