have you tried radio shack? they have an assortment of power adapters for particular pre-set voltages, so it shouldn't go above what it's rated for.

But that's what I already have, I have an adapter that says the ouput is 3V but the actual output is around 4.5V

yeah I found this... http://www.radioshack.com/product/i.....odsInSession=1

sounds like that's what you have now...maybe the purchase of a variable power supply that you can set the output voltage is what you'd need to have a more steady, reliable 3V.

I already have one and it still reads well over 4 volts

it would be a better idea to test if your volt meter isnt broken but using it on a battery or something like that because the volt meter could be showing the wrong voltage

Checking a 1.2V AA battery on the volt meter results in a reading of 1.24 volts...so it's not the volt meter.

will it be running days (like light) or 24/7 ? because it could be a better idea than getting a new transformer to get a solar pannel (reduced emissions and such)

even though the extra 1.5 shouldnt do to bad because ive put 12V through a 9V circiut (the curciut was rated for 6x1.5 C batteries but i blew it when i put 1 amp though it) before and it didnt get to hot you just need to make sure your not puting to many watts though it

It will be running about...5 hours a night for about a month or so >.> I'm not as worried about the motor as I am the diode.

(i am not sure if that circuit was acctually from that or from another thing) you might be able to run it off a battery for that long or 2+ in parralel so it will last the time (whats the motor gonna be doing ?)

Actually, the cheap adaptors usually do provide too much voltage, they're rather crappily made. Try buying a better one, one with a variable voltage setting should be good enough.

I have a variable voltage AC adapter I bought from radioshack. Its lowest voltage is 3V. I checked that at it still reads well over 4 volts.

If you get a veritable Resistor that would work for you . you then can tune in the voltage on what you need.

You wouldn't happen to have a link or anything to something like that would you?

http://www.allelectronics.com/make-.....ometers/1.html
Radio shack has them also.
they are also called Potentiometer

this might help you also http://www.the12volt.com/ohm/page2.asp

Not to split hairs, but that is variable resistor, also known as potentiometer.

Variable resistors should not usually be asked to dissipate significant power.

Ohm's Law is quite a rough place to start for learning Electronics.

What type of motor is it? Does it have any markings for Voltage and Amperage? Question #2 is much more significant than #1 :)

I'm stepping out, but if you can find the answer to #2, I'll definitely try to help solve your problem.

Voltage can be between 1.5 and 3 volts.

There is a label on here that maybe you can make more sense of than I can:

"Current (load): 10A09
0.98A"

That's what it says verbatim.

The motor and the laser diode are the same voltage of 3V...no clue of the amperage of the diode though.

What's rough about V=IR?

Diodes are typically low current drawing devices. I would advise against using a Potentiometer as stated by  lonesadwolf mainly because the current draw of the motor alone with 0.98A. 1 Watt = 1 Volt * 1 Amp. You have 3 volts at 1 AM which would give you 3 Watts of power. Most potentiometers are only designed to work with at most .25 Watts. You can get higher grade pots called Rheostat (Light fading switches are these). Again, I wouldn't use these. Instead, I would use a voltage regulator that can regulate the output voltage from the transformer. These linear regulators look like transistors... and will have to have a heat sync because it will be dissipating the extra volt or so in heat alone. If it gets too hot, it will fail. Another thing you could do would be to use several high wattage diodes in series to drop the voltage slightly. Anyway, I hope this helps out some. :3

Actually, the link  lonesadwolf posted, they do have a 5W Pot available. :P http://www.allelectronics.com/make-.....IOMETER/1.html

If you are going to be getting into wiring things up, you must eventually learn some basic circuit theory; above all, be willing to learn something new. Not only will you get more things done, but you will be less likely to set your house on fire.

But you probably want me to answer your question. I will try. Before you proceed, check what voltage the power supply puts out when it is connected to a load. The open-circuit voltage--that is, when the power supply is not connected to anything--will tend to be higher than the voltage it produces when it is supplying power because of the supply's internal resistance. Hook up some kind of load and see how far the voltage falls. If it does not fall very much, then consider trying to bring it down, but it may fall to three volts.

The motor dissipates three watts of power, as someone said elsewhere in the thread. Thus, a potentiometer is the wrong way to bring down the voltage, unless you like the smell of magic smoke; most potentiometers and, for that matter, most resistors not intended to dissipate a lot of power will handle about a quarter of a watt before they get too hot. What you could use here is a linear voltage regulator circuit of some kind.

Something like this would work:
http://www.satcure-focus.com/tutor/page5.htm
The design there uses a zener diode to control a transistor. (Don't attempt to use a zener by itself to regulate large amounts of power--even a watt is too much--as zeners are small and go up in smoke when abused.) You can get this to work with parts you can find quite readily. All you need is a three-volt zener, a transistor that can handle at least three watts, and a resistor.

Another option is to use a three-terminal regulator. These are just little integrated circuit packages containing little voltage regulator circuits. However, they all have some minimum difference between output and input--the dropout voltage--that the IC requires for ts operation, so you must make sure that the difference between output and input is not less than the regulator's dropout voltage. Also, you must make sure that the regulator can pass the current you need; if not, you will need to use a pass transistor.

Feel free to ask how to do any of the preceding if you do not understand it. If you do not want to do a little engineering, though, it will be easiest just to buy a power supply that gives you the right voltage.

Im curious.... just what exactly are you rigging up here that runs 5 hours a night for about a month?

Laser vortex...

http://www.instructables.com/id/Laser-Vortex/

interesting. Just for giggles, or you gonna be doing it for something specific?

Halloween...

Yes, I'm well aware that it's March....this is my R&D time.

One other thing.

LEDs, laser diodes, and the like care more about current than voltage. Just put the correct resistance in series with the diode. If you know how much current the thing should get (look up the data sheet--it should say what the maximum current should be), just divide the power supply voltage by that current and you will get the correct series resistance. Then pick a resistor that provides at least that much resistance and wire it in series with the diode.

Laser diodes are pretty fragile things. best make sure you know what you're doing. In any case, you can at least keep your voltage at a steady 3v using a voltage regulator:

http://en.wikipedia.org/wiki/Voltage_regulator

Well, there IS a simple solution to it all. Garbage Sale season is coming up, or browse your local junk shop for an older (not really old) model railroad power pack. They put out 18vAC constant and 0-18vDC (usually) variable voltage, reversible polarity depending on which pair of terminals you put the wires to. Poor man's variable power supply.

Open-circuit voltage on power adaptors like this ia always higher than the rated load voltage. Once you connect the adaptor to a load, the voltage will drop to normal.

Actually what you want is a voltage regulator chip, which I believe you can get one rated for 3V. It has 3 pins. V in, V out, and ground. It works just like you'd think it would. Also, I assume a laser diode works much the same as a regular LED, and you will want a resistor between the cathode and the positive supply. Something like 100 ohms is typical.

Motors won't care if you give them higher than 3 volts, they normally will not give out. The diode however would most likely fry if you give it more voltage. Also, resistors are easy to get, just go to radio shack, and remember E=IR.

Double post, woops, but W/E, what supplys do you have so far electronic wise, my friend is really into this type of shit, he might be able to help.