Simple electric circuit

Stupot_ · 2 May 2010 at 22:34

I'm really not fussed about battery life tbh. If I get a couple of hours that's fine.

BigglesPiP · 2 May 2010 at 22:39

If you use the blue lines as the circuit layout, and you use 6 x AA cells in series, you want 270 Ohm resistors on the single branches and 68 Ohm resistors on the double branches.

Stupot_ · 2 May 2010 at 23:21

Thanks biggles, that sounds good. How does this look to buy? I've bought extra in case I want to add lights, the LED's are 3mm 3.3v 20mA.

geowal19 · 2 May 2010 at 23:27

All these diagrams are far too complex. It would be easier to use 12 LEDs. Use 4 LEDs in series then use those in parallel. Hard to explain get in touch if you want more help! This is assuming a 12v source with generic LEDs. You can think of 12V LEDs then you just solder them in parallel mate.

Stupot_ · 2 May 2010 at 23:52

My brain hurts

!

ElvisFan · 3 May 2010 at 00:25

You can buy led's off the bay with resistors and 6" tails of wire already wired in.

I used them to make this sign: (228 Ultrabright LED's wired in parallel from a 230/9v transformer)

BigglesPiP · 3 May 2010 at 11:52

Stupot_ said:
Thanks biggles, that sounds good. How does this look to buy? I've bought extra in case I want to add lights, the LED's are 3mm 3.3v 20mA.

Make sure the resistors are "through-hole" (THT) not surface mount (SMT).

Don't use single core, use flex instead.

Oh, and you've changed the LEDs, instead of 270 Ohm use 300 or 330 Ohm, and instead of 68 Ohm use 120 Ohm resistors now.

Stupot_ · 3 May 2010 at 12:04

Thanks biggles, sorry, I was trying to buy everything from one website!

With resistors, whats the difference between 1/2W and 1/4W, does it matter? also, carbon film/metal film?

These are the ones I have to choose from

http://www.bitsbox.co.uk/resistors.html

BigglesPiP · 3 May 2010 at 12:10

Power doesn't matter, you're no where near the limits of 1/4W resistors here, just get the cheapest. Material is the same, and tolerance, the application doesn't call for anything in particular, just go cheap: 1/4W carbon 5%, 330R and 120R.

Stupot_ · 3 May 2010 at 12:20

Thanks for all your help, now ordered.

Samueltastic · 3 May 2010 at 12:25

Just skim read but may have been said. Make sure the LED are wired in the correct way as they are polarity concious and unless they have polarity protection will blow if wired in wrong.

BigglesPiP · 3 May 2010 at 12:50

Samueltastic said:
unless they have polarity protection will blow if wired in wrong.

No they won't, they are diodes, most will take far more than their Forward Voltage in reverse bias before they break-down and begin to conduct. If you wire them back to front they just won't light up.