9V to 4.5V?

[Tchail]

I'm trying to find a way of taking a 9V current and reducing it by half to 4.5V.

(I know that LEDs run on 4.5V, but I have a blinking light circuit that runs pretty dimly at 4.5V).

I'm using Lightsheet for the nacelles (made by Miller Engineering) and the output requirements are 4.5V and 250 mA.

I found this on Sparkfun.com:

http://www.sparkfun.com/commerce/produc ... ts_id=9370

But I also understand that it's possible to reduce the voltage by using a Zener diode:

http://www.reuk.co.uk/Zener-Diode-Voltage-Regulator.htm

But I don't know anything about these. From what I can glean from the link above, it seems that the Zener diode and a resistor have to be wired in parallel.

Then again...

Any help would be appreciated,

-Tchail

[Umi_Ryuzuki]

You could do it, but you are going to lose running time by dumping
the excess voltage as heat... and nine volt batteries don't have
a whole lot of amperage to begin with. Espcially if you are
trying to run an Inverter for EL lighting...

However maybe you could try one of the switching regulators by
Dimension engineering. They have a 5v, and an adjustable regulator
that might work for you.
http://www.dimensionengineering.com/DE-SW050.htm

http://www.dimensionengineering.com/DE-SWADJ3.htm

Or
You could line up your AA or AAA batteries in series to
run your LED, and then run a tap wire to grab the lower
voltage from the first three batteries.

.

[Tchail]

I'm actually planning on using a wall-wart to power my starship.

-Tchail

[Umi_Ryuzuki]

I'm actually planning on using a wall-wart to power my starship.

-Tchail

Well the resistor will still be dumping voltage as heat...
My impression is that the zener diode stabilizes the voltage.

The wall wart will be a constant voltage, no need for stabilization.
The resistor will be doing all the work.

So you could still use the switching regulators I linked, if they provide
the voltage and amperage you require, and there will be no heat issues.

[Scott Hasty]

Why not just buy a 5V wall wart? Otherwise 3 AA's in series is your best bet...

[Darth Humorous]

Why not just buy a 5V wall wart? Otherwise 3 AA's in series is your best bet...

Most wall warts are unregulated, so there is a good chance it will output significantly more than 5V.

Mark

[Tchail]

My goal here is to avoid using two wall warts - one for the 4.5V circuit and another for the 9V circuit.

I'm sure there has to be a way.

There's an article in "Famous Spaceships of Fact and Fantasy, 2nd Edition" on building the Enterprise D.

The author used 12.6V florescent tubes for the window lighting, and a 7805 Voltage regulator to reduce the current down to 5V to power leds.

Doing a search on "7805 voltage regulator circuit diagram" I came up with this:

http://www.tkk.fi/Misc/Electronics/circuits/psu_5v.html

and this:

http://eidusa.com/Electronics_Kits_Voltage_Reg.htm

It would be a start.

-Tchail

[Madman Lighting]

I recommend Umi's suggestion for the adjustable regulator module.

There's a few reasons:

1) High efficiency, you wont be dumping heat into your model and possibly warping it.

2) Easy. That adjustable 3 terminal rig is probably the easiest way I've ever seen to use a high efficiency 3 terminal regulator.

3) Compact. I'm a super tech with lots of power supply experience. Thats a *very* compact power supply there.

4) Accurate, stable output voltage. May not sound too important but if you want your lights to be flicker free and not be overloaded if the voltage spikes somehow, it matters.

Sure, you could "roll your own" and for someone like me, its easy. For a newbie, buy a module. You'll get the money back in much less frustration.

Good luck.

-John