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  • There's no charge for this electricity. In this project we're making a 40 watt hand cranked

  • generator from these common household items.

  • For this project, let's see if we can make an emergency cellphone charger out of a cordless

  • drill. I have a USB charger that charges this phone from a USB port, and we don't really

  • need the USB head, so let's go ahead and cut that off, then use some wire strippers to

  • remove this outer layer. The shielding can be pulled back, revealing the 4 wires inside.

  • I've done this to both ends of the cable, and stripped the plastic from the ends of

  • the wires. Most phone batteries need around 5 volts to charge, and we can confirm that

  • by plugging the USB head into the port, and attaching some alligator clips to the red

  • and black wires. Using a multi-meter, you can see just over 5 volts of direct current.

  • With the phone in series, the circuit is completed when these wires touch and the phone senses

  • power and lights up. This little black plug symbol shows that it's charging, and it only

  • appears when the phone gets around 5 volts. Ok, Let's build our make-shift phone charger.

  • I have a cordless drill I think I can convert into an electrical generator by running it

  • backwards. I'll remove the bit, take the battery out, and looking up into the handle, you can

  • see the two terminals where the battery would connect. For testing, I'll attach alligator

  • clips to both of them, and then connect the leads to my multi-meter. When I pull the trigger

  • and twist the rotating end of the drill I'm generating around 5 volts, and that's what

  • we need. To make this into an emergency cell phone charger, let's round up a piece of scrap

  • 2x4, a wooden fork, a ball of yarn, a mixing beater, a roll of tape, and some aluminum

  • foil. The first thing we'll need to do is secure the trigger in the "on" position. It

  • won't work unless this button is fully pressed, so let's use plenty of yarn to secure that,

  • then fasten the drill to the 2x4 with as many wraps as it takes to hold it tight. The mixing

  • beater gets inserted into the drill chuck, and when it's fastened in tight we can double

  • check there's no slack when it rotates. We'll need the torque setting to be at it's

  • highest, and confirm the drill is set to reverse. Now it's time to rig the electrical system.

  • Let's rip this sheet of aluminum foil in 2 strips, then fold them into makeshift wires.

  • You can use copper wire if you have it, but aluminum is still a good conductor, and this

  • foil will work in a pinch. These ends are being rolled to a point, and these other ends

  • folded over to make them a little thicker. Now the flat ends can be held in place under

  • the terminal clips of the drill, and since we made these wires so long, let's use the

  • extra length to make sure they're well separated because they'll short out if they touch. A

  • little tape will hold those temporarily, until we can add some yarn to fasten them in place.

  • The red and black wires are stripped down about an inch, and for this phone, we don't

  • need these wires at all. So one cut and they're gone. Now the red and black wires are attached

  • to the aluminum leads, respecting the polarity of the drill. In this case, red is our positive,

  • and the black is our negative. The wires are secured with some more yarn, and all we need

  • now is some leverage for our crank handle. My wife's salad fork will work, and now that

  • we've got our handle, I'm thinking this is ready for a test. I'll start cranking to see

  • what happens, and look at that, the phone lit right up. It's showing the little plug

  • symbol, so we know this is charging, and if I stop, the symbol goes away. It looks like

  • it's working great, so I'm gonna take this inside and clamp it down to a table for better

  • leverage. The crank handle gets inserted, and the system is powered up. The charging

  • symbol is flashing which means I need to crank just a little bit faster for stable power.

  • And there it is. I'm cranking this at about 100 RPM to develop the 5 volts this phone

  • needs to charge. If I crank slower, the phone won't power up, and if I crank too fast, I

  • risk damaging it. Just for the challenge, I'm going to see how long it takes to re-charge

  • this battery from its completely discharged condition. It seems to be taking quite a while,

  • but when I think about it, it takes quite a while even when it's plugged in with a charger.

  • I'm coming up on 3 hours, and I just saw the charging symbol flash off. That means this

  • battery isn't accepting any more charge. It's done. I can disconnect the charger cable and

  • this phone is fully ready to go. If this electrical generator will charge a phone, I'm wondering

  • if it will recharge a battery. I've added metal magnets to the ends of a rechargeable

  • AA battery, so that my alligator clips will attach easily. By attaching the same wire

  • to both ends, we've shorted it out, and the charge is being drained as quickly as possible,

  • and I can feel the battery getting hot. This battery is completely dead now, so to revive

  • it, I'm adding these lead wires in parallel with the system, and connecting them to their

  • respective terminals. It takes about 15 minutes of cranking, and it's harder to turn the handle

  • this time, because I'm pushing a larger electrical current into the battery. Alright, it's done,

  • and a quick test on the meter shows that the battery is fully charged. Well that was educational.

  • I tried shorting the system out on my meter, and got about 6 volts at 7 amps. That's over

  • 40 watts of power. I also tried hooking up an incandescent flashlight bulb, and got it

  • to fully illuminate. A white LED was also tested, and was so bright it actually hurt

  • my eyes to watch. Well there's a makeshift electrical generator that you can make in

  • a pinch, that will charge batteries, illuminate lights, and generate around 40 watts on human

  • power. And it's free. That's it for now.

  • If you liked this project, perhaps you'll like some of my others. Check them out at


There's no charge for this electricity. In this project we're making a 40 watt hand cranked


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B1 中級 美國腔

做一個緊急電話充電器--MacGyver風格! (Make an Emergency Phone Charger - MacGyver Style!)

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    Amy.Lin 發佈於 2021 年 01 月 14 日