I want to make a ac-dc converter so i can wire some led on my fish tank. The power supply form radio shack are pretty expensive and I know i can make one for cheaper and most of all I like to make stuff. So does anybody know a good website where I can find a layout of how to do this?
2007-01-22 23:17:11 · 5 answers · asked by v_bird26 3 in Science & Mathematics ➔ Engineering
Well, I just went through something similar for lighting a dollhouse. I don't know where you have looked at the prices of DC supplies, but the price difference between buying and building isn't really that great.
Your biggest problem is getting the 120V AC down to a usable voltage level. The other two schematics provided for you will work, but the most expensive item is the transformer that steps the voltage down from the utility power. From the research I did around christmas time, those transformers alone were 75-125% the cost of buying a DC voltage source as a package deal.
In the quick once over I gave those other two schematics, it appeared that they were using a voltage regulator chip. Those chips are designed to accept a DC voltage and regulate (lower) it to a another DC voltage. Those chips can cost from about $1.50 to way more than you would want to spend. Some are fixed, producing only one voltage; or variable, producing a single voltage that can be adjusted to a range defined by the regulator design.
For what you said you wanted this for, it seems like overkill to use a voltage regulator. A simple Zener diode (with a resistor in series) could be used to provide a specified voltage to a group of parallel LEDs.
Another cost saver idea is to not use a voltage regulator or capacitors. The output of a bridge rectifer is a like a varying DC voltage pulse train (the bridge takes the one part of the sine wave and flips it to the other side, sort of like folding the AC wave along the y axis). So with standard US power that would make the pulses come at about 120 times a second if connected to an LED. I doubt your eye would notice the difference in output between a smooth DC and the high freq pulse train.
But the best all around way i can think of getting something you can use is to look for some garage/yard sales. Find something for sale that uses an external AC/DC converter and then salvage the parts you need (the DC converter iteslf and the receptacle it goes to). Then all you will need to do is hook up your LEDs and a (possibly) a current limiting resistor. I know it's not as cool as building everything yourself, but if your on a budget it might be something to think about...
But if you do decide to build your own, bear in mind for your safety to include a fuse on the primary (high voltage side) of your circuit. I can't imagine you pulling more than 2 amps, so i would think that should be fine. I would strongly recommend you add this, besides being a general protective feature, you are going to be using this near an aquarium, that i assume will be filled with water, and the higher moisture level can lead to some future problems.
2007-01-23 15:18:28 · answer #1 · answered by TKA 2 · 0⤊ 0⤋
Well it has three main components.
The first is a transformer to step down the AC power to the desired voltage.
The second component is a full wave bridge, which consists of 4 diodes configured top prevent the current from alternating, this will convert the sign wave to a rather bumpy single sided wave form. You can buy the full wave bridge in a single component.
The third component(s) are filters, which are just capacitors which when placed in parallel smooth the DC waveform to a uniform voltage by charging at the peaks of the wave form and discharging in the valleys of the wave form, the more capacitors the smoother the voltage usually three is sufficient.
The above will get you a DC current, however for safety I would recommend a switch and fuse in line with the AC current before the transformer.
I build one back in high school, in my digital electronics class.
2007-01-23 06:22:58 · answer #2 · answered by Brian K² 6 · 0⤊ 0⤋
Look at discover circuits under power supplies, and study ones which are close to 35 amps.. That is a lot of current and I guess you are using some switchers. If not switch to switchers.
2016-05-24 00:23:36 · answer #3 · answered by Anonymous · 0⤊ 0⤋
Here's one that will give you plus or minus 12 volts. If you use only one leg, you'll get one or the other.
If you've never worked with primary power (110 volts) before, just go out and buy one; it's safer ..
http://home.att.net/~eliel/power_supply.htm
2007-01-22 23:27:29 · answer #4 · answered by Gene 7 · 0⤊ 0⤋
AC/DC rules!
They rock on, they kick ***!
LOL!
2007-01-22 23:26:31 · answer #5 · answered by Black Wizard 3 · 0⤊ 2⤋