Hardware Insights Forum

Okay, so I guess there are two reasons for me making this:

• Because I'm bored (yeah, that's starting to set in lately).
• So you can get the brightness of modern, high-efficacy LEDs down to the desired level.

Anyway, I've come up with two circuits for this purpose. One uses a current source in series with the LED and should provide a very stable current; the other uses a Zener-diode shunting most of the current (as provided by motherboards and needed to drive old LEDs to the correct brightness) away from the LED. I haven't assembled them, but I'm pretty sure they'll work.

The "anode" and "cathode" labels refer to the points in the circuit that connect in place of the old low-intensity LED. None of the components used are critical - be they 1/8W carbon film resistors or 2N3904 transistors, they should work (the Zener diode only may get slightly warm but the smallest (0.4W) axial type should be good enough).

In case you're wondering "why not just use a resistor", I made these circuits in order to avoid dependence on which PSU rail is used. Call it overkill if you like, but at least it's less boring this way.