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Discussion Starter · #1 ·
Hi everyone! I made this laser vortex recently and currently the motor/mirror runs on a AA battery and the laser pen uses 2 AAA's. It works and looks great but I'd love to be able to plug it in and not worry about it. Any suggestions on power supplies and such? Here's a photo. Thanks!

 

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There have been a few different methods discussed in other threads on this forum.

One option is to use a hacked computer AT power supply. It will output 12v for the fan and 3.3v for the laser (along with a couple of other voltage options).

Another option is to buy two different "wall warts" (those black boxes that plug into an AC socket and provide DC output) at the correct voltages and use those.

Finally, if you are slightly handy with electronics, forum member CDW designed a circuit that will take a 12v input and provide two outputs, 12v and 3v so that you can use a single, 12v supply to power the whole thing. I used this option and it works great. The post detailing his circuit design is post #94, here: http://www.halloweenforum.com/halloween-props/107283-laser-vortex-complete-10.html
 

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Doh! I just realized that your motor runs on a single battery (1.5 volts).
So, the 12 volt details in my reply don't apply.
You could still use a 3v wall wart, and use a resistor in series with the motor to drop the voltage down to the required 1.5 volts (you would have to know how much current the motor is drawing to calculate the correct resistor size.)
 

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if you don't mind the expense you can use two selectable voltage wall warts, which go down to 1.5V. However many are unregulated, so the voltage can initially go much higher. As mentioned there is pretty good coverage on the forum on powering a laser vortex. You might want to consider a regulated 3V supply, and a 1.5v zener diode to provide the motor power from the 3v supplying the laser. Or one of the $4 step-down dc-dc converters sold on feebay, and a wall wart
 

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Discussion Starter · #5 ·
Thanks for the suggestions. I've obtained two 3v power supplies and I will start working on figuring out which resistor to get since it spins the motor too fast.

Here's another issue I'm having though. When I soldered the power supply to the laser and then set it to reflect off the mirror while its spinning, it looks like there is a break in the beam that rotates around the circle. In other words, its not a smooth/solid cone anymore. When switching back to batteries, its smooth and unbroken again. Any suggestions on why that might be and how to correct it? Thank you!
 

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You can also use a diode, such as a 1N4001 (or pretty much any in that series... 1N4002, 4003, etc.). That will drop between 1.3 and 1.7 volts, so no calculations or current measurements required. :)
 

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Here's another issue I'm having though. When I soldered the power supply to the laser and then set it to reflect off the mirror while its spinning, it looks like there is a break in the beam that rotates around the circle. In other words, its not a smooth/solid cone anymore. When switching back to batteries, its smooth and unbroken again. Any suggestions on why that might be and how to correct it? Thank you!
A resistor or zener should work fine for slowing down the motor. As to the odd break in the beam, it's hard to say exactly what might be causing it; if the power supply is particularly poorly regulated, it might have a significant ripple or other irregularities in the signal. A quick fix might be to put a smoothing capacitor across the laser leads (>1 uF, larger if practical), but that will only work if it's a fairly moderate distortion. Could be worth a shot, though.
 

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Quick question. When using an ATX power supply and the 3.3v for a laser , which runs on 2 aaa and from what I can gather around 300ma. Will the amperage from the power supply be to much and damage the laser. Correct me if I'm wrong, but doesn't the power supply put out about 10 amps on the 3.3 v line.

It would be great to use the ATX power supply cause I have a ton of them and it would eliminate 1power supply.

Thx
 

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Quick question. When using an ATX power supply and the 3.3v for a laser , which runs on 2 aaa and from what I can gather around 300ma. Will the amperage from the power supply be to much and damage the laser. Correct me if I'm wrong, but doesn't the power supply put out about 10 amps on the 3.3 v line.

It would be great to use the ATX power supply cause I have a ton of them and it would eliminate 1power supply.

Thx
Nope, no worries about excess amperage. That's just the capacity of the supply. The laser will only draw as much current as it needs, so long as the voltage is correct.
 

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Thx for the reply. And I take it since people are using this for this same reason, the extra .3v is of no concern?
 

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Yep, 3.3 is fine. A fresh new AA will typically put out around 1.6 V or a little more, so the laser pointer has to be able to handle at least 1.6 + 1.6 = 3.2 V, plus a little extra. You may want to be more aware of potential overheating issues, though, since you're running it for extended periods at its maximum intended voltage.

As a cautionary addendum, what I said in my previous post about current ratings is true for most devices that take a battery or plug-in supply, but there are some exceptions. Most commonly, be wary of things that run off of coin-cell batteries, since some very cheap devices, such as keychain LED flashlights, may be relying on the fact that coin cells have a very limited current capacity to keep from burning out the device.
 

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Quick question. When using an ATX power supply and the 3.3v for a laser , which runs on 2 aaa and from what I can gather around 300ma. Will the amperage from the power supply be to much and damage the laser. Correct me if I'm wrong, but doesn't the power supply put out about 10 amps on the 3.3 v line.

It would be great to use the ATX power supply cause I have a ton of them and it would eliminate 1power supply.


Thx
The laser will only draw as much current (amperage) as it needs. You will not overdrive the laser.
 
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