1.) DO -NOT- regulate the battery source BEFORE the Arduino.. let the Arduino regulate the source itself (should have on-board voltage regulator...no?)
2.) DO regulate the battery source to +5v GOING TO/BEFORE THE: servos & transistor/eye leds
3.) Calculate resistor values based off (source voltage going TO transistor - voltage drop over transistor)
How do we get that?
well source voltage (after voltage regulator) is +5v....right?
the voltage DROP across the transistor is about .7 or so I guess?
so our 'source/supply' voltage is now +4.3v or so..
Use this calculator and fill in the blanks:
LED series parallel array wizard
Source Voltage: = +4.3v
Diode Forward Voltage (voltage your LED needs): = +3.2v *(check you specific LED datasheet though)
Diode Forward Current (current you want to supply your LED, max is usually 20mA): = 15mA
*Number of LEDS doesnt really pertain to you, but add it in anyways..since each led WILL get its own resistor)
calculator says: 82 Ohm valued resistors on each led...
Since you NOW know you are going to supply each led 15mA..
you can add this up.. (say 5 leds [per 'eye'] x 15mA = 75mA total needed per eye)
75mA per 'eye'..... times 2 x 'eyes'.. = 150mA total for the leds....
............now your starting to get an idea of your project requirements.
add in all your other components.. (servo x 2) and anything else you might add.. other accent leds? audio?...etc..etc..
then plan accordingly on your purchases for batteries & voltage/transistor usage..etc..
(servos can take a TON of current under load, depends on the model/brand/load..etc)
Im still confused as to how your only getting +3.4v from your Arduino? where are you metering from/at?
if I plug in my Arduino (Duemilanove 2009) board...and meter the +5v pads.. I get +5v?.. if I meter the +3.3v pad.. I get +3.3v on the meter?...