Help with resistors & circuits Arghhh

I'm trying to set up the circuits in my NX-011 model & having a devil of a time - Any help would be fantastic -

I'm using a 6V - 300ma power supply

I want to hook up the following circuit to the power supply:
Star Trek Enterprise NX-01 Lighting Kit Preassembled Polar Light Star Trek POLAR LIGHTS NX-01 PREASSEMBLED Lighting kit [26TVO06] - $49.99 : Monsters in Motion, Movie, TV Collectibles, Model Hobby Kits, Action Figures, Monsters in Motion

The circuit is designed to run on 4.5V or 3aa batteries, If I'm a litttle hi or low on the power the nacelle dome chasers get twitchy & the nav lights won't flash.

I also want to add 3 white flashing LEDs to the power supply to run the white flashing nav lights. I have the 5mm white flashers from allelectronics, but they don't seem to flash for me - These...
WHITE FLASHING LED, 5MM | AllElectronics.com
They're supposed to operate at 3-5V
I'm hoping if I use the same resistors for three white flashers that they'll stay in sync at least for a while when the power comes on.

I was also planning on piling in a few blue LED strips for the nacelles, plus a few more plain whites & a couple small reds to even out the spinning nacelle effects.

So can anybody who got better than my my "C" in circuits help me out here? Want to make sure I get this right before the hull gets sealed (eventually)

Slowly working my way along - I'm stuck as can be on the electronics - specifically the power supply. The diagram above is what I want to install & I was trying to power it with a 6V 300 amp source (The easy-LEDs run on 6V to 12V) but just plugging in resistors for the monsters in motion kit doesn't work. The MIM kit runs on 6V but not properly.

So I guess I'm going to need a 12V source and then convert it to 4.5 for the lighting kit & leds.

That's where i'm stuck so any electronics wizards got some hints on how to get 4.5 V out of 12V & how to connect all this up?

Easiest option is to pick up a 5v regulator at radioshack. If you want 4.5v exactly you can pick up a variable regulator and set it to the value you want with some resistors.

Thanks, but...

The problem there is the easyLED strips won't fire up below 6V so I need both 12V & 4.5V available inside the model. I want the 12V to get the max brightness out of the easyLED strips.

BTW Jack, Thanks for the response...

First things first: bare LEDs, that don't have any current regulation on them such as your "steady white LEDs", always need resistors, the only exception being if you're using a specially designed constant-current power supply (which you aren't unless you have been specifically told you are). Failure to do this will limit the useful life of the LEDs to perhaps only a few hours, which is an awful situation if it's sealed up inside a model, but it's especially true with white ones that will dim and go purplish-blue very quickly if overheated.

It is not difficult to calculate the required resistor values. I use this calculator, or just do the mathematics. LEDs do not require a specific voltage, they require a specific forward current, and a properly selected resistor will limit that current pretty accurately to the required amount.

The flashing LED may not need resistance because it isn't really just an LED, it's an LED with a tiny driver circuit built in - but check. The lighting kit looks like it already includes them.

Flashing LEDs will not stay in sync for any worthwhile amount of time unless you are spectacularly lucky. You can build a very simple circuit with a single transistor which will allow one flashing LED to control several conventional ones (which will need resistance) and then they'll flash together.

Depending on the situation, you can either redesign your lighting system so that it'll all run from a single voltage, you can provide all the required voltages to the model, or you can provide one voltage and convert inside. I like to use 3mm stereo jack plugs - the sort of thing you have on headphones - to mount models, as it allows you to rotate the model on its mount. These have three (or sometimes even four) contacts, so you can easily supply more than one voltage to the model.

If you really do find you need to convert voltages, I tend to use something like this:

DC-DC LM2596 Converter Buck Adjustable Step Down Regulator Power Module 1.2-35V | eBay

...although there are dozens of types available, just do an ebay search under "DC DC converter." But really, it should be possible to engineer it to all run from 12V.

What do the "Easy LED" parts do? Is it just three LEDs in a board with resistors? I hate to be Mr DIY here, but you can build that for cents and then you get to control how it works and what sort of power supply it needs.

HF

Hfuy, has some very useful information. ^^^^

You could also buy some led kits, that will operate from 9 to 12 volts. They contain
all the parts you need, for whatever effect you may be going for. You could try some other suppliers like electronics goldmine, and bg micro. These kits can sometimes be wired in parallel to the power source and last for hours. It just depends on what you want the kit to do. Alot of the kits may come with red leds, but you should have no problem switching them out. Just check the spec sheet with the kit, and let it run for a good while it before final installation. Although you should try to make some sort of access panels just in case you need to replace a part!

Question: Why are you needing 12V? Unless I overlooked something, everything you listed runs on 6V or less. Are you wanting the 12V to run the LED strips in series?


ATM
ShackMan

Yea, he said he needed the 12 volts for the led strips ( which are rather nifty! )

ShackMan said:

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Question: Why are you needing 12V? Unless I overlooked something, everything you listed runs on 6V or less. Are you wanting the 12V to run the LED strips in series?


ATM
ShackMan

I'm not sure exactly what is meant by "Easy-LED" here, and it's a bit of a generic term to google.

But again, if they're just LEDs in a board with resistors I think unless you have a physical fit issue or some other very specific reason to use them, they seem to be causing more problems than they solve.

They are led strips, that lay flat, and they usually contain smd led's. You can get them
In different lengths, or cut them to the length you want. They are commonly used for the automotive aftermarket ( that's where the 12 volts come in ). Not to mention, you can get different lengths fairly cheap, off ebay. You can hook them up to a 9 volt battery, and they still work just fine.


Now, if space were an issue, regular smd led's could be used. I've started using them on some projects that are tight fit areas, but they are not easy to solder!

Hfuy said:

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I'm not sure exactly what is meant by "Easy-LED" here, and it's a bit of a generic term to google.

But again, if they're just LEDs in a board with resistors I think unless you have a physical fit issue or some other very specific reason to use them, they seem to be causing more problems than they solve.

Oh, right, we're just generically referring to flexible LED strips. Couldn't tell from those one-DPI images.

What's the OP doing with them, I wonder?

Glad you asked - It's all getting stuffed into a 1:350 Enterprise NX-01! The Blue strips will augment the 3 LEDs in each engine, the white strip should help with the saucer, Flashing LED (with fiber-optics) for the little white nav lights & a few extra LEDs to get into some tight spots.

Checked the converter auction - So I could get my 12V by hooking directly to the input wires & connect my 4.5V parts on the other side of the converter? How do you adjust the conversion on those?

You simply adjust the variable resistor (blue box with a brass screw head on top, upper right corner of the picture) while observing the output voltage with a multimeter.

But as I say, you can easily wire up some blue LEDs such that the entire thing will run from 5V or so. Where does the requirement for 4.5V come from in the first place? Can you link to the datasheets for the parts you have?

The 4.5 Volts is the Monsters In Motion lights kit in the picture - It kind of runs at 6V but the nacelle dome lights act wierd & the nav flashers don't flash unless I'm right near 4.5V, also the white flashing LED I'm using for the white nav strobes runs on 3-5V

LM2596 DC-DC Step-down Adjustable Power Supply Module Converter US | eBay

Just ordered 2 of these - They look OK Hfuy? Can't wait to try this out!

Sorry for the fuzzy LEDs - I was just trying to get the idea across - LOL

Those are constant-current drivers for directly controlling bare LEDs.

Those ones are really intended for driving large high power LEDs such as those used in flashlights and lightbulb-replacement devices. You could possibly use them to drive your more normal-sized bare LEDs but they'd be operating right at the bottom of their range and might be a bit unstable.

So no, that isn't entirely what I had in mind

I suspect they will be equally able to act as simple voltage regulators if you wind the current limit all the way up, but I don't have any experience with them.

Hmmmmm. I don't have alot of experience with adjustable voltage converters.
You could just focus on the power supply for the kit (aa's) then wire the other leds to a
differnt power source. That way you know your kit is getting what it needs (power wise), than you can focus on the other led's.

Thanks for the feedback Hfuy - I'll give em a try & report back - in the mean time exactly what specs did i get wrong?

It's not so much a spec, as it is a misunderstanding of what it's for.

Here's a quick intro to how voltage and current work, using a popular metaphor.

You can view voltage as being the pressure in a water pipe. You can have a pipe ten feet across or a pipe a tenth of an inch across, but they can still have water flowing at the same rate. If you wanted to fit a valve to that pipe, you'd have to choose a valve that's specified to withstand that pressure, regardless of the pipe diameter. That's voltage.

You can view current as being flow rate, the bulk of water moving through a pipe. Your ten-foot-wide pipe has a higher maximum rate of flow than a tiny one, but if you only connect a tiny outlet to the end, the actual amount of water moving - the current - might still be small.

You can think of a resistor as a flow-rate restriction device - a tap that's partly on.

So now we understand voltage (pressure), current (actual flow rate) and resistance (flow restriction).

For a practical example, think of a lightbulb. In most circumstances, you supply voltage, and the lightbulb draws an amount of current that's controlled by its resistance. The lower the resistance, the more current flows at a given voltage. Increase the voltage - that is, push harder - and the flow rate goes up. Increase the resistance - that is, close the tap a little - and the flow rate goes down. Voltage, current and resistance are related (the relevant formula is voltage = current x resistance).

If this is not clear please do ask as a lot of things will start to make sense once you understand it.

LEDs have the unfortunate characteristic that, as they heat up, their internal resistance goes down. This causes them to draw more current, which causes them to get hotter, resistance falls further, and you're in a vicious circle that eventually leads to overheating and destruction. In the strictest sense, if you can hold the LED at a precisely steady temperature and keep a lot of other physical parameters identical, you don't need current control - just supply its specified voltage and it'll obediently draw the right amount of current. But achieving that in practice isn't practical.

There are two ways to control this situation. Either you put a fixed resistor in series with the LED such that the maximum flow of current in the circuit is always limited, or you reduce or increase voltage until the correct amount of current flows. The boards you have bought are designed to do that current control automatically, but really they're complete overkill for a simple situation like yours - they're designed to run big high-power LEDs. Using resistors to control current on those is terribly wasteful because the resistors waste power as heat. But for tiny LEDs like yours, not running from batteries, the resistor losses are trivial.

The usual approach is to run LEDs with a series resistor for each one, from a voltage a few volts higher than the voltage specified for the LED. Online calculators will allow you to figure out what resistor value you need.

OK?

HF

Well Good news & bad news - I got the Voltage device to work! Powered everything with a 12V 500ma source. The bad news - I burned up the 555 chip on the Monsters in Motion Board - I've got a new one on order - but I want to replace the fried chip too - Ordered some 555s from allelectronics but as you can see in the photo the chips I got are about 4x bigger - so any suggestions?

Bump for hep with the fuzzy photo!

looks like you bought the wrong kind.

You want an SMT (surface mount tech), or SOP (small outline package) part.

Throw '555 timer' and 'sop' into eBay and you'll get what you're looking for.

Awesome - Got a few on the way! That'll teach me to order without checking here first!

Anybody want a few big 555 chips?