Can kits run off house current instead of battery power?

david banner · Post by **david banner** » Wed Jul 19, 2006 11:19 am

I am a newbie at electronics and I'm sure my lame quesiton here will show you this but I just got to ask:

I notice that all lighting kits for modeling are always based on battery power instead of house current.

What if I want to keep a kit lighted all day and night long? This becomes a real burden having to recharge and change batteries each day.

Is there a way to convert kits to plug into the house current?

There must be a reason why this is impossible or I would expect to see "plug in" type power sources for model kits already for sale in the world.

So what am I missing here?

Umi_Ryuzuki · Post by **Umi_Ryuzuki** » Wed Jul 19, 2006 1:15 pm

Heat is the biggest enemy.
Overheated lamps will soften and defrom a model.
Worst case scenario is the model overheats and catches fire.
Nothing can ruin a day like a flame dripping blob of smoking styrene in your house or apartment.

If you are confident in the lighting set up, wiring, and heat dissipation, then electronic stores often sell low voltage plug sockets lsimilar to those on the side of walkmans, and ipods that can be installed somewhere on the model or the model base. They will also sell "wall warts". Plug in wall transformers that can supply 3-24volts DC and a variety of amperages.

In this manner, you can dispense with the need for batteries, but I doubt it would be wise to run the display 24/7.

Kylwell · Post by **Kylwell** » Wed Jul 19, 2006 1:18 pm

Sure, just use a wall wart. I've even seen models that could swing both ways (battery pack with an interupt plug).

karim · Post by **karim** » Wed Jul 19, 2006 1:37 pm

My moldy crow was built with a base that holds 4 AA batteries. I also added in a DC socket with interrupt pin, so that I can plug in a 6v adaptor. Works fine. The socket automatically disconnects the battery circuit when the adaptor is plugged in. The socket was about $2 at Radio Shack

There's no heat issue, because the adaptor is supplying the same power as the batteries.

david banner · Post by **david banner** » Wed Jul 19, 2006 2:57 pm

So it sounds like everyone is saying that it IS possible.

So it's then just a matter of knowing my overall voltage needs and matching that with the right plug that equals that voltage but not more or I may fry the circuts and LED's etc.

is that correct way of thinking?

I"m currently interested in adapting this idea to the Bandai Trek kits.

Anyone else out there ever do this or know what would work best for these models? I assume the voltage needs is listed in the construction booklet that comes with them.....

Sparky · Post by **Sparky** » Wed Jul 19, 2006 5:14 pm

Neil's Masui had a AA 12 volt pack: It had, two Red leds (bridges), four blues (small engines), one small red (some bump in the front), 2 whites (one po0king out a bump on the bottom, one feeding 2 fibers), and two whites facing out of the little mechanical bays on the bottom of the neck.

All ran from the time he took it the entry room at wonderfest, till he picked it up Sunday (all night).

You can add the auto disconnect like Karim did, and run it off a wall transformer.

Get one or two at radio shack as they are dumping their stock. Pick a plug that matches say a 1/8 inch or 3.5 mm mono/stero jack. They should have that too if they haven't dumped the stock of those yet.

jwrjr · Post by **jwrjr** » Wed Jul 19, 2006 10:13 pm

About 90% of the models that I've lighted run using plug-in power supplies. That way you don't have to worry about replacing batteries that have run down. In larger models, that would happen frequently (My refit has 2 CCFL tubes, 6 light bulbs, and 208 leds).

en'til Zog · Post by **en'til Zog** » Thu Jul 20, 2006 1:25 am

At the moment, I'm looking at a couple of LED units (not exactly models) that I have sitting on top of my Compooter tower. They've been plugged in and running continuously on wall warts for - over a third of a century, each. Guess that answers that question.

If your model doesn't overheat with the lights you have installed and which are running on batteries for hours at a time, I don't think running them on a PROPERLY SIZED wall wart will hurt anything.

Please SEE the article in one of the two "ANNOUNCEMENT"s that head this forum.

Madman Lighting · Post by **Madman Lighting** » Sat Jul 22, 2006 9:05 pm

Yes, its very possible to run models all day but you hafta use a wall transformer to get the house power down to battery voltage.

Heck, my DS-9 runs for weeks at a time and makes a darn nifty night light.

You hafta know what voltage your circuits need and get a wall transformer that produces that, plus you need to know how much current you're going to draw, and make sure the unit can handle the load.

For example:

You want to use six 20mA LEDs and run it off 6V.

LED voltage drop is 3V.

Calculate resistor you need to limit current for each LED: R = V / I
R = (6-3)/0.020
R = 150 ohms.

So now you need six 150 ohm 1/4 watt resistors. Hook resistors in series with LEDs, then hook the resistor-LED pairs in parallel with the transformer output. Done.

This works good for small models with a few lights. Wants a lot of light? Use a CCFL (compact flouresent lamp), or the new high brightness LEDs. Do watch out for heat though, models trap heat and resistor generate lots of it.

-JC.

Kylwell · Post by **Kylwell** » Sat Jul 22, 2006 9:45 pm

Also, just because LEDs will run for a very long time doesn't mean they'll last forever so built it so you can replace them.

If you're planning on running it a lot.

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Can kits run off house current instead of battery power?

Can kits run off house current instead of battery power?

Is it then just a matter of..........