hydranix

The reason this poster thinks that only the computer USB power source was working was because he was hearing the noise produced by the various components in the computer come through the power wires.A battery is a much cleaner source of power than a switched power source like a computer USB port for a project like this.

Primary is input, secondary is output. Simple as that.

No, do not do this, you shouldn't try to regulated a MOT's output voltage by regulating the input voltage.

Do not ever use LEDs in parallel. The cheap chinese LED lights you're referring to are unreliable and can fail if given enough current. Try to use the light with rechargeable versions of the batteries it requires (they can provide much more current than regular non-rechargeables). You'll find the LEDs eventually burn out.Even if using LEDs all manufactured at the same time, they will not have a consistent resistance across them. Further, the resistance of an LED changes dramatically with thermal conditions. If one LED was warmer than the others it would have a lower resistance. It's would pass more current, and heat up even more...This is why we use an series resistor with LEDs when current is not constant. It mitigates most of the unpredictable properties of LEDs.Proper parallel LED circ…

Do not ever use LEDs in parallel. The cheap chinese LED lights you're referring to are unreliable and can fail if given enough current. Try to use the light with rechargeable versions of the batteries it requires (they can provide much more current than regular non-rechargeables). You'll find the LEDs eventually burn out.Even if using LEDs all manufactured at the same time, they will not have a consistent resistance across them. Further, the resistance of an LED changes dramatically with thermal conditions. If one LED was warmer than the others it would have a lower resistance. It's would pass more current, and heat up even more...This is why we use an series resistor with LEDs when current is not constant. It mitigates most of the unpredictable properties of LEDs.Proper parallel LED circuits have a series resistor for each LED.

Galvanic corrosion. A tiny piece of less noble metal, a sacrificial strip so-to-speak, in electrical contact with the metals you intend to protect will do just fine.

Butane can work but will be more expensive as you'll (quite a bit) use more gas to get the aluminum to melt.Propane works and will be cheaper than butane, but still will require quite a bit of gas, unless you have an oxygen fed torch or a powerful air blown torch,For a torch like in the picture (no oxygen or blower) you'll want to use MAPP gas (yellow can) as it burns much hotter and will melt the aluminum using far less gas and cost much less despite being a more expensive by weight.

In sorta layman's terms, a weld molecularly bonds the metals into a single joined piece. Melting a dissimilar metal between the two pieces is just a simple solder joint.

Flourine is very important for our teeth. We have a layer of stuff protecting our teeth and it's called apatite. This stuff is easily dissolved by acids, like in carbonated drinks and in a lot of candy and other things we indulge in too often.Flouride ions bind with the apatite on the surface of our teeth and create Fluorapatite.Fluorapatite is much more resistant to acids, and also naturally kills bacteria it comes into contact with.This is exactly what allows us to keep our teeth beyond our 20s or 30s (which they were evolutionarily never intended to last beyond).If fluoridating water actually showed links to health problems, and the science was real and reproducible, then there would be no reason to continue adding it. Conspiracy theories aside...

use he pwm signal to drive a transistor to pulse the battery

I took the top of a fire extuingsjer that I thought would be the perfect crucible. Fire extinguishers are often made from aluminum. They can do this since the pressure is very low, the gas used is safe, and the content is (obviously) non-flammable.Propane is under much more pressure than the extinguisher, and being flammable even explosive has certain legal requirements, one of which I imagine is requiring either very thick aluminum (not economic) or using a stronger metal like steel.

Will this produce enough heat to melt asphalt concrete (pavement/tarmac). Yes it will melt the asphalt cement in the concrete.How smooth it becomes is entirely dependent on the aggregates in the concrete. Heating it may even make it less smooth as the warm cement loosens and sinks deeper between the aggregates.You'll likely have to roll the hot concrete to smooth it out, the roller size also depends on a lot of things. Anywhere from 300lb to 3ton roller could be required.

Hi jotclot, I was wondering if the whispers were still bothering you, or if you perhaps had seen a doctor for their opinion yet?Don't let the other posters calling you crazy get to you, you're not. Unfortunately though, if you don't see a doctor about it, the whispers could eventually drive you crazy.I hope all is well with you.-

In case anyone was wondering, this is not a night vision camera (as some comments suggested). The cheapest way to get a night vision camera is to just emit a very bright flood of infrared light in front of the camera. Human eyes cannot see infrared light, but cheap webcams can. Get a handful of high power IR LEDs and point them in front of a normal web camera with no modification.This instructable is not trying to make a night vision camera. It's modifying the webcam to filter out most of the visible light spectrum but intentionally not filtering out the infrared light. Infrared light occurs at a lower (electromagnetic) frequency than visible light, and lower frequencies tend to penetrate better than higher frequencies. But that's only partially true. Since almost all humans are very fami…

In case anyone was wondering, this is not a night vision camera (as some comments suggested). The cheapest way to get a night vision camera is to just emit a very bright flood of infrared light in front of the camera. Human eyes cannot see infrared light, but cheap webcams can. Get a handful of high power IR LEDs and point them in front of a normal web camera with no modification.This instructable is not trying to make a night vision camera. It's modifying the webcam to filter out most of the visible light spectrum but intentionally not filtering out the infrared light. Infrared light occurs at a lower (electromagnetic) frequency than visible light, and lower frequencies tend to penetrate better than higher frequencies. But that's only partially true. Since almost all humans are very familiar with the penetration properties of visible light (as we experience it all day long), the properties of non-visible light can be surprising. Infrared light penetrates flesh fairly well, but gets absorbed by blood almost completely. So you can see the veins within thin parts of the body (like hands). Ultraviolet (UV-B) light is a higher frequency than visible light (and UV-A), and just barely penetrates the skin, and is completely absorbed just below the surface along with all the energy of the photon which "carries" the light, which is why it gives you cancer.Woah i got carried away...