Hi,
Noob to forum... Hi

This is a question on the use of resistors in a parallel wiring setup.

I'm planning to install a set of LED's in an RC boat using a 6V battery pack.

I have the following items:
6V Battery Pack
8 - 10 x LED's
On/Off switch

I'm planning on using LED's of different colours (Red, Green and Yellow)
They are all the same manufacturer (3mm Kemo LED's)
1.8V
20mA
625nm

Only the pack of red ones state these specs so I am assuming the other colour will be the same.

My question is regarding how to wire them up and with what resistor(s)

I understand I will need to use a parallel circuit but am unsure where to use the resistors.
Do I need one resistor for each LED?
ie: a 220 Ohm
Or a single current limiting resistor for the whole set?
ie: 27 Ohm

These figure were taken from an LED resistor calculator website.

I have very limited wiring knowledge so I'd appreciate any advice in english please.


thanks

anyone got any advice?

I think either resistor set up can work, single or one for each LED. The single resistor would need to be adjusted if you changed the number of LEDs, you mentioned 8-10 if I'm following correctly. The single resistor would be at a higher power level, ~0.65 watts for the apparent 8 LED example you mention, just need to pick one with enough power rating, with some extra to be safe. The resistor(s) would be in series with the LEDs.

A more efficient option is to put the LEDs in a series-parallel combination. Say use 9 and put them in parallel groups of 3, then put those 3 groups in series. (or the other way, 3 series groups then in parallel, whichever wires easier in the model layout). That would get them up to 5.4V (1.8 x 3), with a single 10 ohm resistor in series needed. Then only about 0.036 watts would be dissipated/wasted by the resistor. Would lower the battery drain from about 0.18A to 0.06A for the 9 LEDs and the resistor.

Assuming all the colors will have the same voltage drop and amp draw is wrong. You should be able to find the specs on the manufactor's website. As for how to wire them, do a search for "LED resistor calculator" and you should find some websites that will do the math for you.

I generally just power mine off the reciever rather than a separate battery. LED's take so little power that it doesn't affect my run time.