9 or 12 volts

belkin321 · Post by **belkin321** » Mon Mar 03, 2014 5:12 pm

Is there a preference as to 9 or 12 volts for lighting models
Thanks

Tchail · Post by **Tchail** » Wed Mar 19, 2014 2:26 pm

I've actually be migrating towards 3v, unless there is some sort of circuit that needs to be driven.

3v allows you to drive white LEDs without the need for resistors.

But then again, you could always put 3 white LEDs in series and drive them off of a 9v source...

Disillusionist · Post by **Disillusionist** » Wed Mar 19, 2014 4:44 pm

I've always leaned towards 12 volts. Good power supplies are easier to come by, and most of the LED strips are designed to run at 12 volts.

Ant · Post by **Ant** » Thu Mar 20, 2014 8:37 am

The only time the lighting in my kits gets demonstrated is at shows, where there is usually no mains supply available so everything is designed to be battery powered.

That means careful consideration over what is actually needed by the circuit, rather than taking what is available and burning off the excess as heat.

Either 3 or 4.5v supplied by AAAs AAs or a CR123A is usually fine. It's a compromise between space available for batteries, and battery life.

Ziz · Post by **Ziz** » Thu Mar 20, 2014 11:38 am

You always want to use as little voltage as possible, for safety more than any other reason, but there's no minimum or maximum - it depends on the lighting you're doing for that individual build.

Just approach it logically. Work out the different kinds of lighting you're installing and what each needs individually. If everything is the same voltage, you're on your way.

If you have different voltages, get a power supply that matches the highest one and use resistors/limiters branched off to cut the voltage down to suit the remaining ones.

And in all this, don't forget about amperage. If you don't have enough of that, you'll either burn out your power supply or you won't be able to run all your lighting at once. Calculate both voltage and amperage as you plan your installation.

chiver · Post by **chiver** » Thu Mar 20, 2014 11:45 am

How do you go abouts to do that? I'm still new to lighting models. And how do you know what to use if you have a strobe circuit in the model?

brt · Post by **brt** » Thu Mar 20, 2014 2:00 pm

Average LED takes 20 milliamps. 50 LEDs would need at least a 1 amp power supply. Better to have a little more than needed, than come up short. If your strobe is off a 555 or 556 timer, you lose about 2 volts through it.
For my project right now, I am using 4 AAs for 6 volts, dropping 2 Volts across the timer for 4 Volts. Leaves me using small resistors.

chiver · Post by **chiver** » Thu Mar 20, 2014 7:32 pm

What about with LED tape? It would be about a foot of blue LED tape, 4 red LEDs and one blue led with a 555 strobe driving a white led

brt · Post by **brt** » Thu Mar 20, 2014 7:59 pm

You need to read the specs on the LED tape. They have built in resistors don't they? So you just need the voltage rating.