Discharging a Capitor? Answered

I have this camera I'm taking apart. The flash unit  has a HUGE capacitor for flashing. When I was taking it apart, I got a shock. I'm fine but I dont want it to happen again. How long will it take for the capacitor to discharge by itself if I leave it for a while?

Question by Adum24   |  last reply


Dishwasher discharges water used in each separate cycle through overflow pipe on sink and not through disposal into drain pipe. The dish-washing cycle is normal. How can I fix this so used dishwasher water leaves dishwasher via water drain rather than through overflow located on top of sink?

Question by denny35   |  last reply


So i'm trying to make a power supply, so for example if i make one with just capacitors (ill put a schematic if i can) and i hook it up to a device,Will it just discharge immediately or will the charge ask for a while?

Topic by minecraftpotato   |  last reply

internal discharge resistor

Well... does anybody know what it is or what it does? i have one its model number is 7C120M33R other stuff written on it are 12 MFD 330 VAC 50/60 HZ 185 degrees centigrade MAX CASE TEMP NO PCB'S product from ADVANCE what cool stuff can i do with this or should i just sell it to buy other neat gadgets?(even though i tried looking for these on ebay found nothing) i took it off a light fixture from a stew leonards store...lol

Topic by Rotten   |  last reply

How to make a static electricity discharge pad? Answered

Is there an expensive way to make an electrostatic discharge pad that I can simply touch before working on my laptop? I discharge myself by touching the screw on a lightswitch plate upon entering my office, but there is always more static that builds as I walk across the carpet to my laptop. My laptop has hung a couple of times because of this and I'm afraid I'm going to fry something for good one of these days.

Question by kredding   |  last reply

CO2 Cartridge discharge thrust?

I am trying to figure out how much thrust would be created with a full discharge of a typical small CO2 cartridge.  Way back when in High School we built CO2 powered drag racing cars in shop.  (I can't remember how we dischardged them?).  But I want to rig a similar device to discharge underwater.  I want it to give a "turbo boost" to a fairly heavy model boat after the boat gets moving a bit.   So it doesn't have to get the boat moving or up to a speed. It's more to give the boat a good push after it gets going. How much thrust would that generate? In water?  I could probably rig 2 cartridges to fire simultaneously on each side of the boat.

Question by JRSanDiego   |  last reply

annoying static discharge problem

I really like these liquid vitamins, but every other bottle I get gives me a long series of random painful electric shocks when I try to open it! You can't hear it, but in the video when I get near the bottle with the probe a snapping sound can be heard. The shocks are seemingly random and some went as high as 500mv. I didn't catch the first shock, which was the worst, from the first time I tried to open the bottle. I tried grounding the bottle, but nothing seems to help. Thanks for any suggestions

Topic by foobear   |  last reply

Variable capacitor and discharge question?

I don't have a variable capacitor of my own to test this so I am relying on the instructable community. What if you have a variable capacitor tuned so that it is at its maximum capacitance and then charge it in a circuit for 5 tau (essentially full charge). Then you completely removed it from any circuit so that you only had a variable capacitor with two (short) leads not connected to anything. Lastly, you turned the tuning knob so that the capacitor had less capacitance all the way to essentially 0 farads. What happens to the stored energy?

Question by seanroberts   |  last reply

How to prevent solar pannel DISCHARDING phone/devices ?

Hi everyone I recently bought a 15W solar charger (without battery) to charge myphone on the go. sadly i discovered that, if the sun is not bright enough, the pannel will actually DISCHARGE the phone battery This is really a show stopper... I'm afraid it might damage the phone battery too. So I was thinking, is there a way to prevent this? I guess a diode in line would be the best option, is it? How about  this: Pannel ==/==> [male USB connector] + [diode] + [female USB] ==/==> USB cable => phone Any ideas? hints? TIA

Question by EmcySquare   |  last reply

I need to keep my dogs from putting their nose on my windows. Design a static discharge zapper with rfid snsing

I need to find a way to stop my dogs from putting their wet noses on all my windows.

Topic by motogp4me   |  last reply

How fast do capacitors discharge?

Do they discharge to 0 volts? pls and thank you (for my school expo project)

Question by mulan2015   |  last reply

Is corona discharge bad in a glass capacitor? Answered

About 2 months ago I built a 60Kv 0.03uF glass capacitor with twenty (5mm or 0.2inch) glass plates. There is a small amount of corona discharge around the edges of the glass. I am concerned whether this small amount of corona discharge could be damaging to the glass is this so?

Question by The MadScientist   |  last reply

need help with capacitance and slow discharge!

I need to make a slow dishcharge capacitor bank capable of discharging 12 volts at about half an amp over about 5 seconds. What sort of capacitor and resistors should i use? It will be powering a short length of nichrome.  thanks :)

Question by kretzlord   |  last reply

Charging and Discharging a battery at the same time?

I've been researching how to make a solar powered boombox and have a few questions about protecting the battery. from solar panel to the battery: i understand that a charge controller is necessary to regulate power to the battery, as well as prevent overcharging it. from the battery to boombox: most projects use an inverter directly from the battery.  I'd like to avoid this step and pull dc from the battery directly to the battery box in the stereo(the ac input of the stereo converts it back to dc again anyway i think).  From what i've read, inverters have a protective circuit that prevent the battery from becoming dangerously undercharged as well as regulate power from the battery.  Could i just build one of these discharge controllers and be done?  Is a discharge controller necessary? cliff notes: what dangers are there in charging and discharging a battery at the same time, and how can i prevent them?

Question by allmondjoy87   |  last reply

old discharged electric wheelchair batteries

My paralyzed wife passed away in 5/2007 and her 2 electric wheelcairs that are no longer in use have thouroly dead batteries. I don't know what kind they are other then they are a sealed unit. I want to sell them but can't with dead batteries. Can they be brought back to life? The on board chargers don't seem to do anything.

Question by Jerry S   |  last reply

Will this capacitive discharge welder design work?

I am planning to build a capacitve discharge welder so that I can tab weld my battery packs, and I have no intention of paying 2K plus.  I recently came across a fairly simple design, and was using it to design my own.  If anyone that has built one of these, or knows how to, can look at this design in detail, and inform me if I have the right componants, and in the right order, it would be greatly appreciated  *** Please, I know the dangers and risks to what I plan on building so please do not express your concerns here.  Everything has risks, but without risks their can be no reward.*** UPDATE I added a new diagrahm with the opto-iso and relay that you two recommended, not sure if its right yet, but its a work in progress

Question by supramp   |  last reply

Solar panel and battery charging/discharging

Hi, I am trying to power some LED decoration from a small 6v solar panel. However, I would like the LEDs to be also on during the night, so working from batteries during night time. I have connected in parallel 3 x AA batteries (800mAh each) to my solar panel (6v, 500mAh), with a diode in between to avoid the battery discharging to the panel. Voltage is fine, and LEDs are working, but I am not sure if during the day, the solar panel is powering the LEDs and charging the batteries, or if the batteries are discharging all the time. If the solar panel is providing more current than required by the LED, does the excess current go to the AA batteries? Is it harder to charge AA batteries compared to AAA, apart from the capacity (mAh) being higher and therefore taking longer? Do I need more mA to charge AA batteries? Thanks, Seb

Topic by SebastienO   |  last reply

Charging in Parallel and discharging in series capacitors? Answered

Most people (okay, well tech guys :P) know that if you put 2 identical capacitors in series you can double the voltage they can handle and you cut in half the capacitence. These 2 capacitors together have 2x the Joules as one capacitor alone. But if you charged them each seperatly, and then connected them in series, would they have 4x the joules as original? For example, lets say I have a 16 volt 100uF capacitor, if each was charged in parallel to 16 volts and then connected in series, when discharged would it have the same amount of power as a 32 volt 100uF capacitor, or would it still have the same power as 2 capacitors charged in series (from a 32 volt power supply)? This question seems kind of stupid, but using what seems like good logic (or bad if your on the other side) you could argue this both ways. But there's only 1 right answer.

Question by guyfrom7up   |  last reply

High voltage discharge capacitor help?

I recently got a 50uf 2000 volt polarized pulse discharge capacitor to blow stuff up. I tried to charge it with a microwave transformer rectified by a single HV diode, but that did not work. My plan was to fire up the microwave transformer, close HV switch #1 to charge the cap, open HV switch #1, and turn off the microwave transformer. Then I would close HV switch #2, and would send power to "load", in this case an orange (see diagram). However, when I closed HV switch #1 (which is a nail in a piece of wood and a rod on a PVC pipe), I would get arcs. Then, when I closed HV switch #2, nothing happened. I even tried shorting the cap with a rod, but it had not charged. Before this test, I tested the capacitor by charging it to 120 volts and it worked fine (I got a spark). Also, there is no internal resistor to discarge the capacitor after a long period of time. Should I try a full bridge rectifier with 4 diodes instead of a single diode? I will also include a schematic of the circuit (you might have to zoom in in order to see it).

Question by TimTD   |  last reply


So, my circuits professor described electrolytic capacitors today, and said that reverse-biasing them could cause a catastrophic, eye-popping explosion. All that in a little metal can? I had to try it! Here's what it takes:

Topic by stasterisk   |  last reply

Rapid decompression cooling? Answered

Is a possible way to super cool a gas (nitrogen or oxygen) to liquid temperatures by using a sub-zero tank of 5000 psi compressed air to blast that gas over a radiator and therefore cool the gas in the radiator to a liquid, then quickly pump it to a chilled high pressure insulated tank.

Question by jj.inc   |  last reply

Flourescent Tube Driver?

So, I'm working on a coilgun, and I don't want to use camera flash circuits to charge the capacitors. Anyway, I've recently come across this, and was wondering if anyone knew what voltage it put out, and current, and stuff like that. Also, if anyone knows an alternate way of charging capacitors to a voltage of 100v - 400v, please share (after all, sharing is caring). Ciao.

Question by LiquidLightning   |  last reply

How do I ground myself from static? Answered

I'm thinking about building my own custom PC but I need to ground myself to protect it from ESD. I can't buy a anti-static wrist strap because I don't know anywhere that sells them and I don't want to purchase it online. I've heard that if you're power supply is plugged in and off that you can touch the edge of the case (the power supply is already mounted). Is this true? Please reply. Thanks.

Question by awang8   |  last reply

Charging a capacitor? Answered

Recently I've had an idea for a project that requires a relatively low voltage (5 to 30 volts) capacitor bank. However, that capacitor bank needs to be charged. While I do know you can easily just hook it up to power, I find that too simple, and lacking of safety, and knowing when it is fully charged. So, could anyone please enlighten me on how i can charge my cap. bank relatively slowly, with, say, an LED that lights up when charged (to avoid them blowing up in my face), and a kill switch/button that discharges the capacitor bank in the event of an overcharge. If anyone could provide an explanation or circuit diagram that would be great, thanks. BTW, the capacitors I was planning on using are http://www.goldmine-elec-products.com/prodinfo.asp?number=G17623 or http://www.goldmine-elec-products.com/prodinfo.asp?number=G16573.

Question by LiquidLightning   |  last reply

How to go about building a Capacitor Bank for rail gun? Answered

Hi, For my physics 2 class our group has decided to build a rail gun. I went to my local Walgreen's and asked for used disposable cameras and the guy was glad to get rid of 20 and give them to me. I researched what "general" specifications for flash capacitors was and it was 330V and holds 270 uF. Before i go about building this bank I have a few questions. 1) From what I understand, you can add capacitors in series to increase the potential difference. ie. for 2 330V capacitors hooked up in series would be capable of 660V and would hold  135 uF (let me know if my math is wrong). My question is that I've heard to be careful and not exceed a capacitor's voltage rating. Is this considered "overloading" the capacitors voltage rating since the bank will be be trying to achieve a max of 660V? 2) Assuming that (1) will not overload the capacitors, what voltage is best to operate a rail gun at, Ive heard that "high-voltage" is best, and Ive seen most around 400V. It seems pointless to hook up 2 capacitors in series to gain this 70V of potential difference, would it be useful in trying to achieve a greater voltages (ie. 500 or 600)? and would I even want to get to 500 or 600 Volts. 3) My goal is to eventually get a semi-large bank with these capacitors having all 20 of them used in the bank. Ive thought of two configurations, one only being possible if (1) will not overload the capacitors. 1) (660V) to have 2 sets of 10 capacitors. Each individual set will be hooked up in parallel acting as a single capacitor, and then in series with each other. The outcome bank (correct me if I'm wrong) would be 660V and 1350uF. 2) (330V) to have All 20 capacitors hooked up in parallel. The outcome bank would be (again, correct me if I'm wrong) 330V and 5400uF. Which would be more optimal? I will NOT go strait into building the full bank, will probably try 6 first and work my way up as I get more comfortable. 3) I'm not sure if all will be rated exactly the same. If some were rated at slightly different voltage ratings and capacitance ratings does this affect my configuration? 4) I was going to use a voltmeter to measure the Potential Difference when charging the capacitors, what is the best way to go about charging a bank like this? Ive heard that by using a singe camera circuit you can achieve this, but at slow rates... what would be a good (preferably cheap) way of going about this? 5) I've heard of capacitors sometimes discharging at the switch. How do I prevent this? 6) (MOST IMPORTANT) How do I safely discharge a bank? What important safety precautions should I take when building this.

Question by Epond89   |  last reply

Q1) after draining a lipo battery to around 3.3v how long can i safely keep it at that level?

Q2) what is the maximum safe time i can store a fully charged lipo before it needs to be used? i have 2 lipo batteries for a speaker trailer and until their first charge and use they are being stored at 3.85v. i have done some google research and i think for the most part i understand how to safely use, charge and store them. They won't be used very often, perhaps 5 times a year on average. 1) i have purchased low voltage alarms so that i will know when to switch everything off however i will in most cases be using the speakers out in parks and fields at least 30mins to an hours ride away from a power socket so would it be safe for the batteries to sit at such a low voltage for around an hour before i can get them on the charger again?  2) previously i used SLA batteries and was able to charge them safely overnight before an event while i slept but according to everything i've read about lipo charging i have to keep a close eye on them while they charge so i would prefer to charge them during the day prior to an event, however i'm concerned that several hours 'storage' at full charge might be asking too much...

Question by ambientvoid   |  last reply

Can a battery to be charge and discharge at the same time? Answered

  Can a battery to be charge and discharge at the same time? i am working on a car use  a 12V battery.I put a dynamo giving 12V on the wheel and i connect the dynamo to a diode then to the battery so the battery can be charged.how can i know if the battery is charging? do i need a voltage regulator? if the battery charged and discharged at the same time will this damage it?   

Question by tarz_00   |  last reply

how to use solenoid with Capacitor Discharge Technology?

Hello guys, i am on a project for a pcp air gun, i want to replace the hammer that open the air valve with electronic trigger, a solenoid to strike the valve open, the travel of the valve is maximum 3mm, a weight will be added to the solenoid to help with kinetic energy. the idea is to use capacitor discharge to activate the solenoid for a fraction of a second (to fire a burst of air propelling the pellet out of barrel) i have seen some electronic triggers using 67v 2200uf capacitor, just to give you an idea. now i want to control the solenoid force and duration. can i do that with arduino? sure i need an external circuit to power the solenoid, maybe like the disposal camera flash?? Please advise. thank you

Question by gerarddag   |  last reply

CO2 canister discharge for arm mounted gun? Answered

I'm looking to modify a simple airsoft gun for the purposes of making the needed weapon props for a assassins creed costume a friend of mine is working on. With that said, the arm cannon/crossbow thing (sorry, I sadly never played the game!) is one I'm playing with now, and I got to thinking about taking a simple CO2 powered airsoft gun, and modding the barrel to take softer projectiles, and to be mounted to someones wrist. The question being: would the discharge from a CO2 cartridge harm someones hand? There will be leather between gun and wrist, by the way.

Question by DoctorWoo   |  last reply

I need to prevent a battery from discharge?

I want to connect an air pump (5-12v) to a car battery. that battery is also connected to a solar charger panel (seen on other instructables). What i need its a circuit where i can monitor the batterry (a 12v cuttoff) so that when it goes below charge, it turns off the air pump, letting it to freely charge and start again. i thought of a NE555 or a relay. appreciate any help.

Question by pchalita   |  last reply

what makes a RC LiPo discharge rate (C) is different ?

Exmple : 7.2v 800mAh 15C, 11.1 2200mAh 20C

Question by Rendydevara   |  last reply

would charging a battery with a motor reduce the battery's life span?

I know that charging and discharging a battery is what "drains it's life" because it holds less and less of a charge each cycle, but is it the amount of charging and discharging, or just the number of times it's being charged or discharged?

Question by the judge   |  last reply

Voltage-capacity relation discharging an alkaline AAA battery?

Let's say I have a fresh alkaline AAA battery, 1.5V, 1200mAh. Also, let's say it discharges itself with 3% per year, just lying in the shelf. After one year, has both voltage and capacity been reduced 3%, or just the voltage? If not, how much has the capacity dropped then? I also wonder if the battery is being discharged the same  way, when in use? E.e. is the proportion between voltage drop and capacity drop the same on the shelf while in use?

Question by karolina81   |  last reply

Can I work on a TV without discharging the CRT?

I have a TV that is in a place where the remote will not work (Dont ask its complicated lol) and I want to rewire the ON/OFF switch on it so that it will be like a foot or two away from the tv. Do I have to discharge the CRT on it before I work on the ON/OFF switch which is only attached by wires to the CRT and flyback transformer circuit. Could I just wear some thick rubber gloves to work on this because Ive never discharged a CRT before and have no interest in doing so.

Topic by jackillac92   |  last reply

Spot-welding Li-ion packs - charged or discharged?

I'm making a large 18650 pack for my onewheel-like hoverboard build. It's my first attempt at spot-welding (DIY spot welder powered with a MOT, scary beast can melt entire M8 nuts on longest impulse time), so I'm afraid I'll mess it up. I was wondering... is it safer/more convenient to work on charged or discharged cells? Does it make any difference at all?

Question by MichałK83   |  last reply

Slow-discharge circuit for gradually diminishing electromagnet field?

As I understand electromagnets, you wrap a wire coil around an iron rod and run current through the coil. As long as there's current going through the coil, you have a magnet... But when you cut the current, no more magnetism... I want to create a circuit in which a hand crank charges up one or more batteries or capacitors, which in turn discharge slowly through an electromagnetic coil (such that the magnetic field of the electromagnet gradually diminishes) over the course of an hour or so. The overall idea is that you crank the crank for a short while, creating a magnetic field so that BBs cling to the electromagnet. But little by little, over the course of maybe 20 or 30 minutes (longer would be OK), the BBs drop off one by one (or a few at a time). Can anyone suggest what such a circuit might look like? What variables will determine how long the crank has to be turned, how strong the magnetic field will be and how slowly it will discharge? And will the BBs only cling to the ends of the electromagnet? Or will they cling along the length of it as well? 

Topic by Donny Bahama   |  last reply

Discharging high amounts of amperage in a very short time.

Previously I asked this question, except I wanted to build an electromagnetic dent puller. But no one gave me specific ideas or instruction of how it could be done, instead everyone told me different ways to pull the dent out, or how the metal looks.. Anyway. I have a lot of copper wire. And I have a bunch of magnets and ferrous cores, iron rods.. etc. I am wondering if I can create a very powerful burst of magnetic energy with a few winding's of copper around a ferrous core. I'm talking enough to push two very heavy objects apart, such as a television or couch... 1) Copper will be wound around about 40-60 times 2) High amperage discharge from capacitor bank 3) Possible explosion or melting wire? Thank you... again

Topic by Justdoofus   |  last reply

Lipo battery charge/discharge on the same port with button?

I like to have the battery charged and used on the same wires with a switch in between. How to achieve this? The switch has a on, off, ground and kill.

Question by DennisK20   |  last reply

Camera Flash capacitor

First off I'll tell you to NOT TOUCH A CHARGED CAMERA CAPACITOR, IT HURTS. I had a disposible film camera that I took apart. How do I discharge it? If I cut one of the leads off the compacitor would it discharge or explode, damage the circuit board? How long would it take to self discharge?

Topic by popit   |  last reply

charging and discharging lipo and lead acid batteries in series/parrallel

Is it possible to charge a lead acid battery and a lipo battery of the same voltage but a different amperage in parallel , and discharge them in series , without one of them blowing up or being damaged? i want to charge a battery pack in series with a 12v charger , and run a 24v dc motor with them...

Question by wiebevandomburg.hotmail.com   |  last reply

What does it mean that the battery I have is rated to discharge at a 20 amp/hour rate ? Answered

I have a 12 volt 5 amp/hour sla battery.  It says it is rated at a "20 hour discharge rate".. What does that mean.  I think that means it is the shortest amount of time the battery could be discharged before damaging the battery.  Is that right ?

Question by Noblenutria   |  last reply

rectify electricity before transformer?

Can you rectify the US mains (120vac, 60hz) as it, and used the pulsed dc to feed into a transformer and get a dc voltage out of the transformer? I'm asking this because it would be much much more efficient for high current situations. Here's my specific situation:I want to build a capacitive spot welder and a capacitive discharge cutter in an all in one device. To charge the enormous capacitor rapidly (1.5 farads in my case), I need a very high current power supply. I'm using a modified microwave transformer that was rated at 1kw, and it is now modified so that it outputs 12 volts AC at around 80 amps (probably less because of losses). This must be rectified to charge the capacitor.Assuming a perfect transformer (for arguement), it would have:120volt, 8.34 amp input12volt, 83.34 amp outputthe following is with full bridge rectifiers, assumed voltage drop: 1.4vIf the power was rectified before the primary, the loss on the bridge rectifier would be: 11.67 wattsIf the power was rectified after the secondary, the loss on the bridge rectifier would be: 116 wattshuge differenceso once again, the final question is: Does rectified input of a transformer = rectified output? Does the 120hz pulsed dc (as opposed 60hz ac) matter? Could this setup charge a capacitor?

Question by guyfrom7up   |  last reply

Can you put SCR's in parallel? Answered

The title said it all. The reason I want to do it is because I want to discharge a capacitor bank into a coilgun, etc, using SCR instead of a large switch. The surge current form the capacitor bank is approximately 400 amps and the SCR's I have can handle surge current of 160 amps, can I put a few of those in parallel to handle 400 amps?

Question by Plasmana   |  last reply

How to Create a Charger and Over Discharge Circuit for 3 NiMH Batteries in Series? Answered

I am wondering how I can create a charger for 3 NiMH batteries connected in series for a portable Raspberry Pi build I am creating. I would also need help creating an over discharge circuit for them so I don't damage them too much. I will be powering a Raspberry Pi and Car backup screen with this. Any help would be appreciated, thanks.

Question by The Lost Puppy   |  last reply

can a piezo electric igniter kill someone? Answered

Im gonna make a taser thing out of a electric lighter will it kill? amd what volts will it discharge

Question by sharlston   |  last reply

how to make solar panels?

it should discharge very small amount of energy

Question by krishna80   |  last reply