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A resistor will work but only at a certain current. So if the device you want to run at 3V has a varying current draw a resistor won't work. However 3V linear regulators are cheap and easy to use. If you don't need much current they are also very small. Like if you want to hardwire a remote instead of batteries, the regulator will be no bigger than a pencil eraser. If you need around an amp they will get bigger. If you give me some more info I can help you out with more details.
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Actually these are key chain lights. Has a small chip board inside and has a 3volt watch like battery inside. It is almost like a blue laser but diffracts quickly to make a blue spot light that is supopsed to be visable up to 2 miles. I am puting these in my head lights for a parked mean ass glow.
Hope that helped a little. And yes I want to hardwire it in with a toggle instead of using the push button switch on the key fob housing.
Or if it would be easier I would run both lights and boards of one hardwire instead of separating them.
posted
A linear regulator will be the way to go. The current from those coin cells is pretty minimal so even the smallest regulator will work. You can just use one regulator for both lights and wire a switch between the 12V and the regulator. I'll find a data sheet for you on them.
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On the topic of linear regulators..... I know nothing about these, but would they be useful say if you wired two 12volt batteries in series, ran it through the regulator down to 16 or so, and then to the amps??
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posted
The linear regualtors wouldn't work for dropping 24V down to 16V for amps. The reason is the large currents the amps need. If the amps take 100A and the voltage is dropped from 24 to 18V the regulator needs to dissipate 600 watts. That makes the whole setup very inefficient.
Zeners would work fine in this situation, it helps to know the current needed by the device but in this case we could probably assume around 20mA per light and get close. I just figured a regulator would be easier to use than a zener.
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Just an actual experience fact : if choosing between a 1A or a 100mA regulator (e.g. 7805 vs. 78L05) ALWAYS ALWAYS ALWAYS go for the 1A version. They are the same price, and the stability of the 1A version is infinitely better.
This cost me about $40 to learn, and I give it to you for.....FREE.
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Like the other guy said, you could wire four of them in series.
Also, go to your local department store and look around where the Walkmen are. They have inexpensive devices that you plug into your cigarette lighter, which drop the voltage down to hook up your Walkman. You could buy one of those and hardwire it behind the dash.
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Posts: 16 | From: Malden, Massachusetts, USA | Registered: May 2001
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posted
If you like to DIY, pick up a LM317 and build your own regulator. Parts should be less than $5 and it's a great learning project. Radio Shack should have these for a buck something. Here a link to a data sheet for the LM317: http://www.onsemi.com/pub/Collateral/LM317-D.PDF
I built one for my garage door opener because I'm too cheap to buy new batteries and I made a remote switch for a cleaner look.
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