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I have done "tapping" or jolting many times and not a single cell has even warmed up. Today I just did it twice! The current is too low to cause damage and the supply may warm up if the cell is shorted. But most bad cells are open and will not charge from a dedicated 4.2 VDC regulated supply (you can measure the current), so a "jolt" can kickstart the cell revival.I began this "tapping" on NiCad cells using a 15 VDC, 30 A battery charger. That generated many sparks but never an "explosion" or even a warm up. So 9 VDC is low enough to avoid damage and yet enough to "jolt" the cell.
As an additional note, there may not be any known recycling center near your home, but you may ask battery sellers. I have one nearby (Batteries Plus) that will take in any type, rechargeable or disposable, and handle them for recycling. I give them all the lead-acid batteries from my UPS equipment, too.
All good advice, but I have revived a few 18650 cells by tapping the ends with a higher DC voltage. I use a 9 VDC 0.3A (300 mA) supply, and I tap the ends several times then measure. If the reading is over 2 VDC, then I can use a standard Li-ion charger overnight and see if it hold the charge the next day Of six Panasonic cells that I recovered from an IBM ThiinkPad 600 laptop battery, four were revived.
A third note: many smartphone use flat Li-ion cells that have a protection circuit in them. The top plastic cap may have three or more contacts where only two are for power and the others are for temperature sensors to detect heat These also have overvoltage and overcurrent protection chips inside, so there are tiny FET switches and a fuse in that circuit. If you measure zero volts, then the fuse or a FET is open. The cell cannot be reused in a smartphone.But if you are willing to experiment and take a risk, then remove the packing and the plastic caps. The protection circuit is on the negative electrode of the cell and the metal body is the positive. There is a small metal strap electrode that carries that side to the circuit. Removing the cap and disconnecting the electrodes from th...see more »A third note: many smartphone use flat Li-ion cells that have a protection circuit in them. The top plastic cap may have three or more contacts where only two are for power and the others are for temperature sensors to detect heat These also have overvoltage and overcurrent protection chips inside, so there are tiny FET switches and a fuse in that circuit. If you measure zero volts, then the fuse or a FET is open. The cell cannot be reused in a smartphone.But if you are willing to experiment and take a risk, then remove the packing and the plastic caps. The protection circuit is on the negative electrode of the cell and the metal body is the positive. There is a small metal strap electrode that carries that side to the circuit. Removing the cap and disconnecting the electrodes from the circuit allow you to measure the cell directly (be careful as the entire metal body is the positive!). If it has a voltage, then use alligator clips to charge and remeasure. If it does hold a good charge, you may find a use for this cell later. But if nothing happens, just have it recycled.
AC is more efficient to move power than DC because in a direct current circuit, the electrons move from atom to atom in the conductor, while in an alternate current circuit, the power is moved as waves due to the vibrations (60 Hertz). Higher frequencies can move even more energy (that is how cellular phone service works). This is how tidal waves can move so much power across lakes and oceans. Tesla was trying to move free energy using large transmitting towers but failed. Yet even now we move our data across high frequency waves (Bluetooth, Wi-Fi , FM , TV, and cellular) thanks to Nikola Tesla's inventions.
I have a king-sized bed made in 1989 that is similar, but uses mirrors and fluorescent lamps. The mirrors reflect the floor and covers the normal platform side walls. The lamps have two 2-way switches so any side can turn them on or off. I have replaced the fluorescent lamps with LEDs but it still works as a "floating bed".
No, you cannot use the phone company's power to charge your devices. It is limited to several milliamps (mA) and they can measure that consumption, indicating an "off-hook" condition as if you were activating a phone. And if the limit is exceeded, they can do a "disconnect" and you are left without phone service. Don't tryit unless you wish to pay for a line reconnection at the CO (Central Office). If you wish to know more, you can ask the phone company or just search the Web.
I do for over 40 years! The phone company supplies 48 VDC battery power with its own UPS and generators. So if there is a general power failure, your home phone will still operate, but your cellphone may not! Besides, without power, how can you keep your cellphone charged?
Eye protection is always needed when you handle wire, because a strand can break loose and fall into your eye. And if you have ever cut solid wire, the force can eject a piece of wire into your eye!. I use prescription glasses so I am indirectly protected. But whenever you manually handle wire, solid or stranded, put on safety glasses or goggles, and save your eyes.
I see what was done here. The "wart" isn't "gone", but just mounted where it would be unseen. Having both the 120 VAC and the transformer output (lower AC voltage) in the same pipe for a short distance isn't a fire hazard and I see it acceptable. I would go even better by opening the "wart", removing the plug inside, wiring the 120 VAC line directly to the transformer wires, close up the "wart" body, then hide the "wart" inside the outlet box, and put a blank cover on it.
The primary reason that the electrical code exist was to prevent fires. The first NEC (National Electric Code) was written by the Fire Deprtament of New York City over a hundered years ago. And if your home ever gets burned, and the fire instectors detects that a bad electrical connection, not done by the code, was the cause, your fire insurance will not pay!!
I suggest covering the plastic tip with the cutoff finger of a glove so it does look like a human finger is pushing the switch off.
This is a very useful guide, but why "a hot hair tool"? Even if it were a "hair dryer" the temperature will never reach the melting point of solder.
I have a special charger that holds two 18650 cells and has built-in protection, so I don't need the protective circuit.
Great idea using the NO to short the load current. I would also recommend use a "push off, push on" switch that mechanically toggles and keeps the switch in the pushed position, so you can let go and it will still stay off.
Each unit is a "cell" ,and the "battery" is the whole group (I wonder what fool started the single "battey" mistake years ago). Each cell can be measured individually between its two electrodes without disconnecting it. That is how the author finds which cell has to be removed and substituted with a better cell from a donor battery.
I have revived bad NiCad cells from the "shorted" malady or ailment by striking (hitting) the electrodes with the contacts of a car battery charger (uses rectified and unfiltered 12 volts) for a few times. Sparks fly because of the internal short, but that fuses open the short and revives the cell.
I aghree. The hand drawn schematic is very hard to read. If you can't use a professional drawing program, ask someone who has excellent drawing skills to do it for you. And I ask if you wired the twin heater filaments of the 12AX7 in parallel with the heater filament of the 6V6.
The original equipment has their vacuum tubes exposed to release the heat. Only certain equipment needed metal shields over the vacuum tubes to isolate the internal tube elements from stray magnetic fields or radio signals.
Marconi invented the wiremless transmission of noise (from a spark generator) and the first use was wireless telegraphy. The first tuned (frequency stable) wireless transmission for audio, which is what we call "radio" was invented by Nikola Tesla. Tesla even had to sue Marconi for the "radio" invention.
The car charger has a switching voltage regulator inside that can handle DC from 6 to 30 V, so even two AA, C, or D cells in series can charge your smartphone. And if the voltage is too high, don't worry! A regular car can generate up to 16 V, which the same charger can handle, too..
The car charger has a switching voltage regulator that can handle a wide range from 6 to 30 Volts, so any external source of DC power 6 volts or higher can power it and charge your smartphone. And for the high voltage question, a regular car can generate only up to 16 V, so the car charger can handle that, too.
The 2,5V of the LED isn't any "internal resistance". It is the junction voltage that all semiconductor diodes have to pass and allow the current to cross the PN junction (the joint where the "P" and "N" semiconductors meet), and it varies according to the elements and doping used to create the semiconductor itself. This is why a germanium diode conducts at only 0.47 VDC and silicon diode conduct at 0.68 VDC. Light Emitting Diodes use different elements and doping for each color, so its PN junction can be as low as 1.7 VDC and as high as 4.5 VDC.
I wish to correct the author:"Old audio jacks (Use 3.5 mm jack)"That is the wrong item or description. The correct item is a plug since the jack is already in the smartphone. I recommend correcting this error soon because I may be the first of many comments about this error.
I built a platform bed in 1984 and added glass mirrors along the bottom panels that reflect the floor up to the viewer, making the bed really look like it was "floating" and had no legs. Then I added 4-foot fluorscent lamps under the overhang (invisible to the viewer), and improved the "floating" image. Now I have replaced those lamps with LEDs and keeping the image of the "floating bed".
Great project, but it uses a prefabricated LCD and video board. I believe many wish for a cheaper project using a LCD and electronics from an existing device (smartphone, tablet, etc). I see the external interfacing as the main problem, but it can be done.
Yes, that size is okay. I see a 5-inch screen as the practical limit for a small handheld monitor, unless the font size can be increased. I have seen a small 2-inch LCD but only had a 4x16 font size for text. The smallest monitor could be a wearable one-inch LCD with an eyepiece to see a virtual screen as big as 12 inches floating ahead. That would be a great project, too!
I could recommend adding a microswitch to the sole/heel from the inside. Cut a slot inside under the clothcover to fit the switch. Wire it up in series to the battery supply wires. Then when the wearer steps down,the LEDs light up. It saves power if the wearer is sitting or standing on the foot edge.
I believe the comment comes from someone who has 230 VAC as their "mains' voltages, not just 120 VAC and "neutral" as we have. So this application may leave one live wire on the supply as the SPST toggle switch just opens one line. For better safety and prevent any voltage on any supply line, use a DPDT toggle switch to open and control both lines, leave the unused switch contacts open, and insulated the switch in a plastic enclosure. Adding the "ground" or "earth" is a good safety option.
According to the CD players that I have taken apart (similar to the DVD player), there is a five-sensor photodiode that reads the reflected laser light. One is the main data reader, and the other four are arranged around the main reader to confirm and keep the laser pointed inside the track, If one or two of the sensors misses the signal, then the MPU will step the head motor to recenter the track and keep reading. I have watched a CD player operation and you can see the head being stepped as the CD is played.
It should be "Needle Nose Plier", not "neddle nose Piler". I suggest to all project posters to run your text through a spellchecker before posting the final Instructable. Other that that, you can ask a friend or senior to read the text before posting.
Most laptops can use low DC voltages, and don't need a regulator since they have one built in. So just put two 12 VDC batteries in series ans pass that through the DC input.As for the weedwacker, you may be surprised that its motor works on DC already! They have a diode bridge to rectify the AC going in to 160 VDC average, so you can either string several 12 VDC batteries in series, use a 12 VDC to 120 VAC inverter, or make a 160 VDC boost supply (the weedwacker need no regulation).
Plastic Bottle Mosquito Trap
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