LMFAO Robot Head

Want to just shoot the breeze? Forum 42 is the place!

Moderator: Moderators

Post Reply
WTB360LABTOP
Posts: 56
Joined: Mon May 16, 2011 7:15 pm

LMFAO Robot Head

Post by WTB360LABTOP » Wed Oct 19, 2011 6:57 pm

I plan on making a LMFAO robot head for Halloween. I am planning on using a carboard box and putting packing foam on the inside so it is tight against my head. Then I'm cutting out a mouth a putting mesh over it (you see out of it) and for the eyes I am going to use 3 leds on each eye. How would I run 6 leds off of 1 battery?

Image

I'm also thinking about putting 4 white super bright leds on the front near the bottom so I can see where I am walking.

cross
Posts: 14
Joined: Sun Oct 02, 2011 7:30 pm

Re: LMFAO Robot Head

Post by cross » Wed Oct 19, 2011 7:08 pm

Hehe, sorry I used search function wrong.
If you find a AA battery pack from radioshark you can wire it up to some leds using a basic wiring. If its just for a night I have just slapped on a random resistor and it works fine (Use 220 ohm on a 3v line, thats how my Gameboy DMGs are allwired fine and thats with two led)
Last edited by cross on Wed Oct 19, 2011 7:45 pm, edited 1 time in total.

WTB360LABTOP
Posts: 56
Joined: Mon May 16, 2011 7:15 pm

Re: LMFAO Robot Head

Post by WTB360LABTOP » Wed Oct 19, 2011 8:02 pm

Question, i just read online that if you supply an led the exact voltage you don't need a resistor. Would it be possible to wire 6 3v leds in series (I think its series, might be the other) onto a two AA battery pack without a resistor?

cross
Posts: 14
Joined: Sun Oct 02, 2011 7:30 pm

Re: LMFAO Robot Head

Post by cross » Thu Oct 20, 2011 11:33 am

Well by that logic they would be underpowered. But if theyr the same voltage they should be fine, you power a PS1 with 7.2 volts from the battery which it asks for without it breaking, the leds will be the same

User avatar
jdmlight
Posts: 795
Joined: Thu Dec 27, 2007 11:17 pm
Steam ID: jdmlight
Location: A boring suburb of Chicago.

Re: LMFAO Robot Head

Post by jdmlight » Thu Oct 20, 2011 11:47 am

WTB360LABTOP wrote:Question, i just read online that if you supply an led the exact voltage you don't need a resistor. Would it be possible to wire 6 3v leds in series (I think its series, might be the other) onto a two AA battery pack without a resistor?
That may or may not work.
jdmlight wrote:
minnieman wrote:i just need to power 2 3v leds and i am using 4 AA batteries. how should i aline them to power the 2 leds? i have them in a straight line right now but no power is getting to the leds. any help?
You need a resistor with LEDs, always. LEDs aren't so much concerned about the voltage, but rather the current. (to a point, you have to have at least the minimum voltage specified and there is a maximum) Typically you'd aim for around 20mA current. (.02A)

To calculate the resistor you need, take the voltage you have (4xAA = 6v), subtract the voltage that the LEDs take (6v-3v=3v), and divide that by the current. (3v/.02A = 150 ohm) You can pick a higher value resistor, but lower will probably burn out the LEDs. (higher value resistor = dimmer LED but also = less current drawn, which may be important for a portable) This isn't magic, it's just the V=I*R formula. (V=volts, I=current in amps, R=resistance in ohms)

In this case, you can't put the LEDs in series (straight line) because each takes 3v, so if you have two of them, you're trying to calculate the resistance necessary based on 0v, which ends up being infinity. Which is impossible.

tl;dr: Go here. :P
From here.
--John (and please call me John, it's really weird to be called by my username)
Fight MS Paint abominations! If you don't have a camera, go here, and pick something 3 megapixels or higher.

WTB360LABTOP
Posts: 56
Joined: Mon May 16, 2011 7:15 pm

Re: LMFAO Robot Head

Post by WTB360LABTOP » Thu Oct 20, 2011 5:14 pm

Image

User avatar
jdmlight
Posts: 795
Joined: Thu Dec 27, 2007 11:17 pm
Steam ID: jdmlight
Location: A boring suburb of Chicago.

Re: LMFAO Robot Head

Post by jdmlight » Fri Oct 21, 2011 10:48 am

jdmlight wrote:You need a resistor with LEDs, always. [snipped the rest of this]
tl;dr: Go here. :P LEDCalc will answer all of these questions.
--John (and please call me John, it's really weird to be called by my username)
Fight MS Paint abominations! If you don't have a camera, go here, and pick something 3 megapixels or higher.

User avatar
Turknatr12
Posts: 191
Joined: Sun Jan 27, 2008 9:00 am
360 GamerTag: turknatr
Location: Richland Center, Wisconsin, USA, North America, Earth
Contact:

Re: LMFAO Robot Head

Post by Turknatr12 » Mon Nov 07, 2011 7:50 pm

Here is one I made for my Homecoming:
Image

I used 2 regular LEDs in each eye and also a 5 LED mini flashlight in each eye, mounted inside pop cans for reflectivity, and there's a switch to control it on the back.

Image
"Look at you, flying through the air majestically, like an eagle piloting a blimp."
http://www.youtube.com/user/RMSJaggers?feature=guide" onclick="window.open(this.href);return false;

Post Reply