flex rapidfire cg2 optocoupler power drain

[manwinder]

my battery runs out of power in like 30 minutes after i do a full charge, i am using a 4.7 ohm resistor on the optocoupler, could it be the battery. i have modded the leds to red and blue, could it be the led's.

[Anonamous]

try using a different set of batteries or using real AA batteries.

[Hazer]

4.7 Ohms is way too small. You need at least 100 ohms.

V = I*R

The optos LED is most likely 2V@10mA. Since the battery is 3V, the drop across ther resistor should be about 1V. For 10mA, this would be R = V/I = 1V/0.01A = 100 Ohms.

With a 4.7 Ohm resistor, you are probably sourcing 100+ mA and draining the battery real fast.

[magic_man185]

Hazer,

Wouldn't the opto actually be running off less than 3v?  The led of the opto is being powered by the analog voltage of the controller, which is like 1.5V to 1.6V.  The 3V is on the other side of the optocoupler on the collector, which then flows through the emitter to the rf chip when the controller is powered on.  The thread by RDC on using an opto actually says 10 ohm resistor (granted he does say it depends on the optocoupler).