Voltage Drop Resistor

Every Christmas i put  togather  Christmas wreaths for the front of cars,

Last year I found some Battery power lights Two different sets i use one has 4 Dbl A  Batterys

the other takes two  C Batterys, this year With the help of someone out there 12 volt land,

I'd like to connect them to the  Parking lights. I have a limited knowledge on OHM's Law'

I know  I have 12volts that have to drop 6 volts or  3 volts I like to learn more .

Thanks Mark

hi,

well if you use christmas light sets that are meant for use at home...110 volt that is, determine if the set is two independent strings.  if it is, divide half the number of bulbs into 110v.  that will give you volts per bulb.  then cut the set into strings that will operate on car voltage..14v or so when running,

example....100 light set, 50 lights per string, 110v/50= 2.2v/bulb, 14v/2.2v/bulb~~7bulbs.  so cut the set into short strings of 7 or 8 bulbs.

run strings in parallel for more lights, or a bigger wreath. 

hope this helps

mark

...or you'd need an ammeter to measure the current that flows through the sets that you have.   then  you'd have car voltage minus set voltage divided  by current of set...that would equal the value of the resistor you require.  you also would need to take that current squared multiplied by the resistor value to get a wattage rating for the resistor...plus a safety factor, (double the wattage value) so as to not burn up the resistor

more info for you

m