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I always put a 1N4007 diode in there to lower the voltage to an atomizer-friendly 3.7 Volts.
Forget about them. They're taking up so much current when plugging in the device that your USB port is immediately overloaded. I've tried 
Been using this mod for a while now. Current draw has posed no issues with the two units I've built, and the atomizers are holding up well to the 4.8v my USB port puts out. I may end up adding a small dongle to lower the voltage to 4v later, but I'm in no rush as it's performing wonderfully just the way it is. I have no idea what you are referring to aaa and I'm not sure you do either.
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Why not just make it mains instead? Get something that does 3.7v and can take the current and shove the wires on the atomiser? OK I'll pack my things and order a Kissbox
just a quick point, you will get away with using this on a desktop pc as each USB port is capable of delivering 500mA. I would not recommend trying this with a laptop / notebook as the USB ports on Laptops / Notebooks only deliver 100Ma accross all the USB ports. In other words if you had 4 USB ports on your laptop / notebook thats 100Ma accross all 4 ports. Chances are if you plugged your device in to a USB port on a laptop / notebook you would overload it and possibly cause permanent damage.
P.S. I have 35 years experience with computers and through my job I provide tech support for the MOD.
P.S. I have 35 years experience with computers and through my job I provide tech support for the MOD.
I've been experimenting with homebrew devices for a little while now and also tested on an 8 year old Toshiba laptop. When using capacitors the port gets overloaded but it's nothing serious. Just reboot the machine and the port is reset so it's pretty well protected against over current. If you really want to play safe I'd recommend the Deal Extreme 1000mA USB adapter which is not only very cheap but also delivers enough oomph to power an e-pipe!
http://www.dealextreme.com/details.dx/sku.2381
http://www.dealextreme.com/details.dx/sku.2381
Where's the BS flag icon...I have a test lab with 14 laptops at my house. I've tried my modded 901 cable on every USB port on every laptop here. It works fine, and doesn't damage ports. Who told you laptops are only capable of 100ma? Who told you the port would blow? If the USB port can't supply the current it just won't have enough current to work the way it's supposed to. If you take a 1a power brick and plug it into device that requires 2a... how do you suppose the 1a power supply is going to be damaged? What's going to happen is the device won't work because there is not enough current being supplied to it. This doesn't damage the power source. Either way you look at it.. I've tested it on 15 machines, probably close to 40 ports total. I even tried on 2 micro laptops with 10" screens. Smokes great. Ports still work. I would need to make a cable to measure the current draw on the atomizer from USB power...haven't done it yet but if I get around to it I'll post it up.
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Where's the BS flag when you need it
hahahah ... J/K J/K ...
stop heckling me Steve! lol I can make a video of me testing on 15 computers if anyone calls BS! I'm a wireless networking engineer and my "lab" is based out of my house. This means I just happen to have a crap load of laptops handy to test the USB cable with.
OK Guys, Absolutely no BS, it is true. The usb port on a laptop is not capable of delivering 500Ma. We had a lot of trouble in the past with usb powered scanners that would work happily on a desktop pc but not on laptops because the usb ports on the laptops were not man enough to power them.
Bastage: put a multimeter in line and read the current difference between desktop pc and laptop usb ports when you use your device.
Yo Han: check it out on the internet (google it whatever).
Anyway I'm not bothered whether you believe me or not, the advice was given freely it's up to you if you want to take it or not.
Bastage: put a multimeter in line and read the current difference between desktop pc and laptop usb ports when you use your device.
Yo Han: check it out on the internet (google it whatever).
Anyway I'm not bothered whether you believe me or not, the advice was given freely it's up to you if you want to take it or not.
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It is within usb spec not being able to plug 500mA devices to all usb ports. Or you can plug em but they will not all work. Like I said before, usb spec does not allow devices to draw more than 100mA of current until they negotiate with host. As wiki puts it "All devices default as low-power but the devices' software may request high-power as long as the power is available on the providing bus". 1.5 amps is still quite alot even though other devices connected would only need 100mA.
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One thing to think bout here is that when Voltage goes up amperage decreases - especially in a simple heating circuit such as an atomizer. Using Ohms law we can determine that IF with a 3.7 volt battery is drawing 1 amp of power for the atomizer then the total resistance of the coil (atomizer) is 3.7 ohms. Since the coils are very tiny the variance in manufacturing is probably NOT all that stringent any change in the length of the coil would vary resistance and increase or decrease current draw ( Maybe a cause for dying atomizers - short coil / Could lead to a higher than normal current draw and a battery could get fried also after having to "work" harder) Anyway if we use 3.7 watts as the "BASE" needed for said coil at 5 volts you will only require .74 amps or 740 milliamps a 25% saving on the amperage and much closer to the 500 milliamp spec of the USB port
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