Dangers of plugging a 5v device into a 9v adapter?
You're right -- there's no problem in going over the amperage limit. In fact, you should. The device will draw as much current as it needs, and it's best to have a comfortable cushion. Same thing as your household electrical outlets. They're rated at 15 amps, but you can use a radio that draws maybe 100 milliamps. I wouldn't use a 9-volt adapter for a 5-volt appliance. Even though most low-voltage electronics stuff has a very wide tolerance, nearlyh doubling the voltage would be a big risk. There are some fairly simple electronic circuits that you could wire together to drop the voltage, but that's unnecessary. The easiest solution would be to go to your local Radio Shack store and buy an adapter for the plug. It will have US flat prongs for the wall adapter and the two round plugs from your VGA/HDMI adapter fit in the other end. (If your plug is some other shape, you can probably find others as well.) These things are widely available online as well. Radio Shack charges $7 for them. That's a rip-off, but if you buy online you'll get hit with shipping charges that are three times the value of the thing anyway.
Is there a way to tell which laptop charger is mine?
Heya, As long as it's not a cheap-as-chips charger which was hastily made and not safety checked, it shouldn't do any damage to your computer if you at least attempt to plug it in. If they're both HP branded, at the very least it won't do damage so you may as well try both. If neither work though then you'd probably need a better charger, most manufacturer's basic chargers are cheap and never last the lifetime of a laptop - this is coming from someone who's had five company laptops in the last three years and never had a single charger outlast a computer!! A good charger will exhibit: - Auto voltage-switching (so you don't have to use a screwdriver to select a voltage, and accidentally get it wrong) - Meets western (US/Europe, one or the other or both!) safety standards, this kind of thing basically ensures chargers have adequate surge protection, various failsafes in case of an incompatible connection, et cetera. - Are actually in English as opposed to really broken Chinese (a lot of cheap Asian chargers look like this) on the packaging and instruction manual, this is usually a giveaway of a bad charger if the language used is rubbish! I personally got mine from universallaptopchargers.co.uk after cycling through a few cheap ones on Amazon. One out of three of my old ones worked but eventually overheated so I bit the bullet and grabbed one that was a bit more expensive, and didn't really regret it - I charge my phone and my laptop at the same time now and sometimes leave it at my desk at work so I don't have to remember to lug a phone charger around. If you're not UK-based I *think* they ship internationally, but you may want to e-mail to make completely sure. They may also have some vouchers running around here and there, so you may want to ask around in case there's a discount somewhere. Good luck! Please best-answer me if I've been helpful :-)
Is it possible to charge a 6v battery with a 12v charger?
I figure that's a 6Ah battery. 1A for 6 hours should fill it up.Here is the datasheet for the BD681.The transistor is a bit on the small side for comfort. It's only a TO-225 type rated at 4A (& 40W). A bigger TO-220 device with a rating of at least 10A would be my choice.Remember it's a very simple circuit with no safety features of any kind so it needs to be dimensioned fairly well to survive (but the 4A might survive if cooled well enough).Steel (or brass for that matter) is a very poor heat conductor and will not do at all as a heatsink material. Aluminum and copper are the only common metals that'll do.An aluminum "sheet" would also need to be at least 3 mm thick and 20 x 20 cm to come close to being up to the task. Copper is much better and can be thinner (1mm).You might even consider water cooling (like a small pan, if you dare).. PVC tape is also a very poor heat conductor, as you noticed. If the heatsink is well protected from touching anything else then you can do without transistor insulation.A small drop of (cooking) oil between the transistor & the heatsink/ underside of the pan could make do as a heat transfer improver.Anyway, this charger may help you Liang's FM Transmitter,the Best Wireless Bluetooth Handsfree Car Kit/Adapter, with USB Port/Car Charger for Cellphones Power Charging iOS & Android iPhone, try it7ATest the output voltage of the circuit first without connecting the battery. The battery, being small, will not draw as much current as a car battery does, fooling the indicator.A battery resting voltage of 5.8V means it's very flat indeed. 6.4V would mean it was full however (not much of a difference).For measuring currents you usually have to move the red test lead to a separate socket on the meter (and remember to move it back before measuring Volts again).
What happens if I use a 6v AC adapter on a 9v electric piano?
No. This poses no risk of a fire hazard as it is not enough power to operate your unit as the manufacturer intended. If it works at all (on the 6 Volt adaptor) it will be like trying to run it on low batteries and not provide volume and/or undistorted signal(s) as desired. I suggest that you visit a store like Wally World as they will have an adaptor that will work well for your unit. Be sure to note the polarity of your keyboard and choose an adaptor that will have the right power and voltage said unit requires. Most units will have the polarity, voltage and current ratings printed or embossed next to the port where the adaptor plugs in. If it calls for an adaptor of 9 Volts DC @ 900 mA (0.9 Amps Direct current) you should choose an adaptor that has (at least) 1.0 Amps DC (1,000 mA) available. This will insure proper desirable operation of your keyboard. If you have the Owner's Manual on your keyboard you can refer to it for the proper power requirements. Feel free to e-me. Happy Holidays!
The end of my charging cable fell in water. What do I do?
Just let it dry out. If you can, and especially if the water it fell in wasn’t clean, rinse it well in distilled or at least deionized water before you dry it out. (Contrary to popular belief, pure water isn’t a very good conductor, and is used as a cleaner or rinse in many electronics manufacturing processes. It's contaminants dissolved in water, esp. salts, that cause trouble for electronics.) The drying process can be sped up a bit by putting the cable in the sun or in some place where you can keep it at, say, 120–150 deg. A hair dryer on low may also help.Really, this is no big deal. Cables get wet all the time, and as long as you take care of cleaning any gunk off and drying them before using them, you’ll have no problems.