Hi,
I m currently modifying an xbox server - removing CDROM drive, installing wireless router board, adding USB connector board...
I was lucky to source a front panel SMD LED strip (with buttons!) from a dead dell monitor. It's interface was a common ground with an anode connection for each LED (bicolour so two for each). The plan was to take one of the grounds from the supposedly common ground router front panel light supply, and then wire the anode connections straight on. It seems the circuit path went from the microprocessor output straight to the appropriate LED, and then each went back through a 330ohm resistor (SMD network) with the back ends tied, going what I then thought to be the ground plane. It seems this was wrong, as after wiring it up and no success, I checked with the multimeter and indeed the voltage was reversed. Also, as it was common ground on the front panel connector, I tied the resistors together at the other end too, as I was worried that it might not handle the power of all of them if I had everything on (4 LAN ports, wireless and IO controllable LED - so 6 SMD LEDs) - so I decided to er 1/6 the resistance and trust the SMD LEDs, as I didn't have any data for them anyway (reckless, I know!)
So, I currently have a predicament. I need to turn a common source into a common ground. Is there a simpler way of doing it or would I need 6 lots of a PNP transistor driver thing (still reading up on PNP transistor circuits!). I could disconnect the resistor bridges I put in place and connect them to the anodes, but then I would have all the IOs trying to connect to 1 ground pin, an no, er, control?
So is it a case of inverting everything, and am I doing someting fundamentally wrong with shorting the resistors together? If you need a diagram to explain, I can draw one up!
Thanks so much,
Laurence
I m currently modifying an xbox server - removing CDROM drive, installing wireless router board, adding USB connector board...
I was lucky to source a front panel SMD LED strip (with buttons!) from a dead dell monitor. It's interface was a common ground with an anode connection for each LED (bicolour so two for each). The plan was to take one of the grounds from the supposedly common ground router front panel light supply, and then wire the anode connections straight on. It seems the circuit path went from the microprocessor output straight to the appropriate LED, and then each went back through a 330ohm resistor (SMD network) with the back ends tied, going what I then thought to be the ground plane. It seems this was wrong, as after wiring it up and no success, I checked with the multimeter and indeed the voltage was reversed. Also, as it was common ground on the front panel connector, I tied the resistors together at the other end too, as I was worried that it might not handle the power of all of them if I had everything on (4 LAN ports, wireless and IO controllable LED - so 6 SMD LEDs) - so I decided to er 1/6 the resistance and trust the SMD LEDs, as I didn't have any data for them anyway (reckless, I know!)
So, I currently have a predicament. I need to turn a common source into a common ground. Is there a simpler way of doing it or would I need 6 lots of a PNP transistor driver thing (still reading up on PNP transistor circuits!). I could disconnect the resistor bridges I put in place and connect them to the anodes, but then I would have all the IOs trying to connect to 1 ground pin, an no, er, control?
So is it a case of inverting everything, and am I doing someting fundamentally wrong with shorting the resistors together? If you need a diagram to explain, I can draw one up!
Thanks so much,
Laurence