Driving LEDs straight from Relay outputs

[skippy178]

Thanks Don

I did have a look at the RC and Spike specs, but neither gave definitive figures on the amount of current (if I am wrong, please point me to specific page numbers !).

The page on the RC at IFI Robotics site

http://www.ifirobotics.com/rc.shtml

mentions 7mA for the Digital I/O pins, but says nothing about the Relay ones.

In response to your message, the short answer to my question should be that with 5V on the FWD and REV pins of the RC when they are switched on, and assuming a 1.5V drop across an LED (being a typical figure), that leaves 3.5 volts to drop across the series resistor. For a 10mA current, that would require a resistor of 350 ohms (or higher to give a lower current).

The nearest E12 resistor value is 390 ohms - the next lowest, at 330 ohms is too low and would give too high a current.

OK ?

Jason