modessitt
Volunteer: Encyclopedia Submission Moderator
Lighting an LED when I don't know it's voltage rating..
I'm in the process of converting an XArcade control panel into a test bench panel. I've done all the rewiring, but I noticed there is a small red LED mounted in one corner set flush with the top of the CP. Apparently it was a power LED to show the MAME box's IPAC-clone had power.
I'd like to hook it up to the +5 of my switcher. My switcher is an older style that doesn't have an LED. I know the +5 is fused internally, and that it can shut down from an overload, and be restarted later (sometimes) after a few minutes. An LED would let me know whether the +5 was active or not.
The problem is - the LED looks to be epoxied into place. No removing it to look for markings. I know I can but a resistor in to drop the +5 down to whatever the LED needs (maybe 3v?) but I need an idea of the voltage requirements of the LED before I can figure out which resistor to use (already found an online calculator that will tell me the resistor size).
What do y'all think?
I'm in the process of converting an XArcade control panel into a test bench panel. I've done all the rewiring, but I noticed there is a small red LED mounted in one corner set flush with the top of the CP. Apparently it was a power LED to show the MAME box's IPAC-clone had power.
I'd like to hook it up to the +5 of my switcher. My switcher is an older style that doesn't have an LED. I know the +5 is fused internally, and that it can shut down from an overload, and be restarted later (sometimes) after a few minutes. An LED would let me know whether the +5 was active or not.
The problem is - the LED looks to be epoxied into place. No removing it to look for markings. I know I can but a resistor in to drop the +5 down to whatever the LED needs (maybe 3v?) but I need an idea of the voltage requirements of the LED before I can figure out which resistor to use (already found an online calculator that will tell me the resistor size).
What do y'all think?


