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That makes sense -- I'd thought about it at first, but then I wondered if there was a possibility that the stick was reading both sides simultaneously. I suppose that would be pretty dumb and have absolutely no benefit, though, so it's highly unlikely. I'll give that a shot.
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Sep 15, 2010 08:44
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Doesn't matter if the stick is reading both sides. The change in resistance in one side will still change the centre voltage.
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Sep 15, 2010 08:54
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ante posted:Doesn't matter if the stick is reading both sides. The change in resistance in one side will still change the centre voltage. Yeah, there really is no such thing as "reading both sides." It's a voltage divider, the joystick works by measuring the voltage at the center terminal. That's it that's all.
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Sep 15, 2010 09:01
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Hillridge posted:That's a microcontroller: The reference is T1, does that make it as transformer.
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Sep 15, 2010 21:41
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Unparagoned posted:The reference is T1, does that make it as transformer. Not necessarily. A transformer is just two coupled inductors (somewhat simplified, but I could see a lazy board designer not changing the labels). How many leads does it have?
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Sep 16, 2010 00:35
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Is there a way to discharge a capacitor/circuit if you can't access the leads to the capacitor? Everything I've read says to discharge a cap by connecting the leads to a big resistor. I'm repairing a Rear Projection TV and don't really want to gently caress around with it until the big cap (120v 1000uF) is discharged...but I can't get to the capacitor leads unless I gently caress around with the TV to remove the board. Catch 22 here  Any suggestions would be appreciated!
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Sep 16, 2010 00:54
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polyfractal posted:Is there a way to discharge a capacitor/circuit if you can't access the leads to the capacitor? Everything I've read says to discharge a cap by connecting the leads to a big resistor. I'm repairing a Rear Projection TV and don't really want to gently caress around with it until the big cap (120v 1000uF) is discharged...but I can't get to the capacitor leads unless I gently caress around with the TV to remove the board. Catch 22 here I thought modern electronics were required to have bleed resistors on caps. 5 minute discharge maximum, IIRC.
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Sep 16, 2010 01:02
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babyeatingpsychopath posted:I thought modern electronics were required to have bleed resistors on caps. 5 minute discharge maximum, IIRC. Ahh, did not know that. Its a 2003 model, so I assume its "modern" enough to have bleed resistors. Is there any way to check if this circuit is equipped with one? Edit: Oh god I need to find a yellow pico fuse rated at 3.15 amps. Any ideas where I can get one? I've checked the sites listed in the OP and can't seem to locate it. Does the yellow code mean fast or slow blowing? Can I replace it with a green equivalent-rated fuse? polyfractal fucked around with this message at 02:32 on Sep 16, 2010 |
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Sep 16, 2010 01:07
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Is there any good way to limit current without dropping voltage as with using a resistor?
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Sep 16, 2010 01:57
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BattleMaster posted:Is there any good way to limit current without dropping voltage as with using a resistor? Interesting question. I wish I had an answer for you  All of the ways I know of off the top of my head are either going to be effectively dropping voltage (say, abusing a lm317 to make it a current regulator) or some sort of switching circuit to get average current. Would your load be okay with the voltage switching on and off to get the average power (and therefore current) at the right value? I've done this with LEDs, but they are pretty much the most tolerant constant-current application I can think of.
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Sep 16, 2010 03:07
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BattleMaster posted:Is there any good way to limit current without dropping voltage as with using a resistor? What are you trying to do? Since V=IR, if your current is constant then the voltage will be proportional to the load. Do you just want to supply a constant voltage, with a max current? What behavior do you want when your load exceeds the current limit?
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Sep 18, 2010 16:36
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I'm trying to create a type of VR machine. I'm trying to plan out what I'll be using. I don't want to start only to realise I've completely gone down the wrong path. There are two parts, physics and visual. I can do most of the physical stuff based on a PIC. The visual stuff is simply playing a video, well there will be about 5 videos that loop. Syncing the video to the physical effect is quite important. So my problem is I can't seem to find anything to tell me how to make something that will play a video from say a memory source(say a SD card for example). I've found a few projects that use a PIC to make a pictures frame. But I don't think the chip will be able to handle video(either uncompressed will be too much info or it will be too hard to uncompress info). Pretty much the visual part is going to be like this http://www.zetronix.com/product_info.php?products_id=125. So say I wanted to make a very simplified version of the above device how would I do it. It just needs to play video from an "on board" memory source.
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Sep 18, 2010 23:00
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Delta-Wye posted:Interesting question. I wish I had an answer for you I have a question about pulsing the power. Let's assume a 50% duty cycle. It would essentially halve the current because only half as many electrons would move in the same amount of time. However, during the on periods wouldn't a larger amount of electrons be flowing in the same amount of time than if the current were halved and the power wasn't pulsed? What kind of loads are tolerant to that? SnoPuppy posted:What are you trying to do? Since V=IR, if your current is constant then the voltage will be proportional to the load. Ooops, I forgot about how Ohm's Law applies to this situation. I guess you can't really limit the current drawn by a resistive load without changing the voltage or resistance.
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Sep 19, 2010 03:50
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BattleMaster posted:I have a question about pulsing the power. Let's assume a 50% duty cycle. It would essentially halve the current because only half as many electrons would move in the same amount of time. However, during the on periods wouldn't a larger amount of electrons be flowing in the same amount of time than if the current were halved and the power wasn't pulsed? What kind of loads are tolerant to that? Inductive? I was thinking switch mode current supply, basically. Although I'm just kind of bullshitting without any idea of the application.quote:Ooops, I forgot about how Ohm's Law applies to this situation. LEDs are one case where I think you can gain a bit this way without needing a switching supply. My understanding is they are tolerant of a higher peak current than they are constant current (as would be sensible) but the human eye detects peak brightness so you can can eek out a bit more visible brightness with the same average current. Not something I have really explored because usually LEDs are plenty bright and I don't have any reason to go through the overhead for something like this, but there ya go. Delta-Wye fucked around with this message at 08:37 on Sep 19, 2010 |
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Sep 19, 2010 06:46
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Talking about driving LEDs, does anyone know of a cheap 12V/1A LED driver IC? I only need 8 distinct levels out of it.
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Sep 19, 2010 08:00
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Delta-Wye posted:Inductive? I was just wondering about how it would work in theory, I don't have an application in mind. Except... quote:LEDs are one case where I think you can gain a bit this way without needing a switching supply. My understanding is they are tolerant of a higher peak current than they are constant current (as would be sensible) but the human eye detects peak brightness so you can can eek out a bit more visible brightness with the same average current. Not something I have really explored because usually LEDs are plenty bright and I don't have any reason to go through the overhead for something like this, but there ya go. I might be building some IR stuff to go with a friend's night-vision equipment and exploring that to get brighter LED output might be worthwhile. Unless the NVGs don't pick up the peaks and pass them on to the user's eyes.
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Sep 19, 2010 16:35
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BattleMaster posted:I was just wondering about how it would work in theory, I don't have an application in mind. Except... Basically, you try and average the current using a big switch. Current going to low? Turn it on a bit! Current going to high? Turn it off for a bit! Assuming you have something like an inductor smoothing the output a bit and you have a load that will tolerate it, it can be pretty efficient. Certainly more efficient than a resistive approach. Hell, you could even use something like a step down voltage converter to feed a linear current supply. Tie the feedback pins so that it floats just about whatever voltage the current supply uses and then you'll have nice smooth current and (possibly) greater than ohmic efficiency. http://www.extremecircuits.net/2010/06/switchmode-constant-current-source_14.html
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Sep 19, 2010 19:16
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Unparagoned posted:I'm trying to create a type of VR machine. I'm trying to plan out what I'll be using. I don't want to start only to realise I've completely gone down the wrong path. I found this, http://www.sparkfun.com/commerce/product_info.php?products_id=10089 . It's based on PICASO-GFX2 which is a 4DGL chip. I couldn't find much about this chip which may make using it a bit harder to use. But I couldn't find any alternatives. If I get the above module it seems like it should be easy to get used to and get working quickly. Any advise?
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Sep 19, 2010 20:34
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Delta-Wye posted:Basically, you try and average the current using a big switch. Current going to low? Turn it on a bit! Current going to high? Turn it off for a bit! Assuming you have something like an inductor smoothing the output a bit and you have a load that will tolerate it, it can be pretty efficient. Certainly more efficient than a resistive approach. That's pretty badass. I'm going to give it a try next time I need to build some electromagnets. Thanks!
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Sep 19, 2010 22:04
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Unparagoned posted:I'm trying to create a type of VR machine. I'm trying to plan out what I'll be using. I don't want to start only to realise I've completely gone down the wrong path. I'd probably go with something like a BeagleBoard if you want to do audio/video type of stuff. It should have more than enough processing power to decompress most videos, and it already has dvi, svideo, and audio outputs. You can also run linux on it.
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Sep 19, 2010 22:39
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Are there any good off the shelf chips for converting an analog audio signal to some sort of digital representation of volume and pitch (MIDI essentially)? I'm sure it could be done with an FPGA, and I figure someone has to have made a cheap simple solution.
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Sep 20, 2010 19:16
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Hillridge posted:Are there any good off the shelf chips for converting an analog audio signal to some sort of digital representation of volume and pitch (MIDI essentially)? I'm sure it could be done with an FPGA, and I figure someone has to have made a cheap simple solution. Isn't this essentially describing an ADC? TI makes parts that will toss out I2S to feed to a micro-controller. Or did you mean a discrete IC that does all the work without an external micro (straight analog audio->volume + pitch)?
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Sep 21, 2010 16:41
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Spent all day at the danish E10 electronics congress, was interesting to see the high tech industry and it's suppliers from the "inside" Spent a while chatting with the awesome guys at RSonline, who have this great website: http://www.designspark.com/ where there's shitloads of relevant information, and also their Designspark PCB application. it should apparently beat EAGLE right out of the ring, while being free! (they were situated right across from the Farnell booth, was pretty funny to see them lure in people after they left the farnell booth to tell them their stuff was better and free  )UPDATE: hahaha, two hours we left, a bomb threat was called in at the congress center. awesome Frobbe fucked around with this message at 18:39 on Sep 21, 2010 |
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Sep 21, 2010 17:44
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movax posted:Isn't this essentially describing an ADC? TI makes parts that will toss out I2S to feed to a micro-controller. Yeah it could be done with an A2D and a micro, but I was looking for more of the latter (an analog->midi IC).
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Sep 21, 2010 18:23
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Hillridge posted:Yeah it could be done with an A2D and a micro, but I was looking for more of the latter (an analog->midi IC). I'm afraid it's more complex than that for any real instrument. A "note" has a lot of harmonic content (timbre) so you have to take that info and figure out what note it was, which probably involves a buttload of FFTs and power calculation. We tried it with a DSP about 12 years ago, didn't get all that far with it.
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Sep 21, 2010 19:23
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Cross post from amateur radio thread: I'm not an expert in electrical engineering, but I'm drat sure this is the finest Linear power supply circuit I've come across for a hobby guy to build. The same dude also has a 40a switching power supply circuit too.
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Sep 21, 2010 20:30
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SnoPuppy posted:I'd probably go with something like a BeagleBoard if you want to do audio/video type of stuff. It should have more than enough processing power to decompress most videos, and it already has dvi, svideo, and audio outputs. Interesting, but it seems a bit like overkill. I can make a 3D computer gaming system with that BeagleBoard. I just need something to play video and do some other basic stuff.
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Sep 21, 2010 22:33
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Hillridge posted:Are there any good off the shelf chips for converting an analog audio signal to some sort of digital representation of volume and pitch (MIDI essentially)? I'm sure it could be done with an FPGA, and I figure someone has to have made a cheap simple solution. I really wish such a thing existed, but I'm pretty sure it doesn't. As long as your signal is dominated by its fundamental frequency, doing dirty pitch detection isn't too difficult. I've always wondered what those electronic pitch detectors for tuning instruments use.
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Sep 22, 2010 02:31
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That's exactly what I was thinking about when I asked that question. I have one of those digital tuners and while I haven't opened it yet to check, there can't be that much to it.
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Sep 22, 2010 13:02
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I just cracked open an old one of mine. There's one of those blobs of black epoxy hiding/protecting whatever processing crap is there. Can't tell what's there, or how many dies there are, but whatever it is, it does just about everything, including amplification, sampling, processing, and display, so it may very well be an ASIC.
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Sep 22, 2010 13:19
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Anyone have any suggestions for cheap entry level soldering irons?
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Sep 24, 2010 10:01
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Just get a $15 Radioshack iron. It'll work until you know what you're doing and want to upgrade.
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Sep 24, 2010 11:27
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Don't waste your money on a Radioshack firestarter. For the same $15, this iron (http://www.mpja.com/viewallpict.asp?dept=461) will last a lot longer, and do a much better job.
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Sep 24, 2010 13:34
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I'm building this device that uses both a microprocessor and a dsp. The microprocessor is going to do all the user i/o (have most of this mocked up using development boards) and then hopefully transfer commands to the dsp via something like i2c or spi. The dsp will be doing audio filtering according to the user i/o passed on by the uproc. The issue I've ran into is I don't know how to program the DSP - I mean, in a physical sense, as I don't know how to get a program onto the DSP. You can bootload it a couple different ways (from I2C flash, USB, etc) which seems fine, but how to you get the program onto the flash or whatever? When I imagine something like this, it seems insane. For something like I2C flash, would you have to usb bootload a program that takes the real program and dumps it into the I2C flash and then boot off the flash on the next run or what?  I feel like I'm making this harder than it has to be. I have a ezDSP development board and I'm starting to work on the code, but I would like to build a custom design for the project and having a hard time figuring out the easy way to do this. It's obvious with the microcontroller; IDE talks to usb->jtag programmer that plugs into the header I've put on the board. I don't really see any info about an equivalent for DSPs (if it matters, one of TI's TMS320C55xx series, maybe a 5509A for USB capability, I'm not sure yet). Are there any good resources explaining this? It seems like such a silly part of the project to get hung up on. Zuph posted:Don't waste your money on a Radioshack firestarter. For the same $15, this iron (http://www.mpja.com/viewallpict.asp?dept=461) will last a lot longer, and do a much better job. Delta-Wye fucked around with this message at 22:31 on Sep 24, 2010 |
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Sep 24, 2010 22:28
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Delta-Wye posted:I'm building this device that uses both a microprocessor and a dsp. The microprocessor is going to do all the user i/o (have most of this mocked up using development boards) and then hopefully transfer commands to the dsp via something like i2c or spi. The dsp will be doing audio filtering according to the user i/o passed on by the uproc. I haven't dealt with DSPs, but I have worked with FPGAs quite a bit and I think the process would be similar. Either you have to have something else that can talk to the flash (like your micro maybe? or header pins you can plug an external programmer into) and use that to load the flash/control the DSP, or you have to do what you suggested. Just from quickly looking at at TI's website, it sounds like they all have an integrated bootloader, and some can read an SD/MMC card. You could just throw that down and then program you SD card with any computer. TI also might have tools which let you read/write memories hanging off the DSP, but I'm not sure if they're free.
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Sep 24, 2010 22:59
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Hey guys I've been struggling with a particular topic on electric potential, if anyone can help me understand. Say I have 2 battery's both 9 volts potential, why will current not flow if I connect one battery's + to the other battery's -. Now I know the answer is because the circuit is not closed, but what I'm having trouble understanding is why this makes a difference. If there is still a potential difference from one + terminal to another - terminal won't this create the driving force for the valence electrons to flow towards the positive terminal in our system. What is it about closing a loop that only then allows current to flow? Sorry if this is a dumb, but it's been racking my brain.
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Sep 24, 2010 23:29
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SnoPuppy posted:I haven't dealt with DSPs, but I have worked with FPGAs quite a bit and I think the process would be similar. http://dspdap.sourceforge.net/firmware.html Yeah, totally fugly. I'm planning on using a msp430 (reading two ADCs and writing to an SPI LCD can be done with anything, but it's what I know) for the microcontroller, and I'm totally used to running code constantly as I'm working on a project. It would be nice to have debugging support and stuff, especially considering I'm totally new to DSPs. Oh well. I guess, at worst, I can always use my ezDSP to develop the algorithms and just use the custom board for showing off milestones.
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Sep 25, 2010 00:32
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Popete posted:Hey guys I've been struggling with a particular topic on electric potential, if anyone can help me understand. Say I have 2 battery's both 9 volts potential, why will current not flow if I connect one battery's + to the other battery's -. Now I know the answer is because the circuit is not closed, but what I'm having trouble understanding is why this makes a difference. If there is still a potential difference from one + terminal to another - terminal won't this create the driving force for the valence electrons to flow towards the positive terminal in our system. What is it about closing a loop that only then allows current to flow? Sorry if this is a dumb, but it's been racking my brain. You can use the water-in-pipes analogy. Treat batteries as pumps, and electrons as water. All of the piping you use is completely full of water. If you have a circle of piping, then the pumps will continuously circulate water around the loop. If you break the circle, that is, take out a section of pipe and cap the ends, then the water has nowhere to go. The pumps are still trying to push water forward, but nothing is happening.
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Sep 25, 2010 00:59
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ante posted:You can use the water-in-pipes analogy. Instead of pumps, think of the batteries as water tanks. The top of the tank is +, the bottom is -. The water level in the tank is voltage. Since both your tanks are at the same voltage, then the water is at the same level. If you connect the top of one tank to the bottom of the other, no current flows because the water level in both tanks is the same.
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Sep 25, 2010 01:06
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babyeatingpsychopath posted:Instead of pumps, think of the batteries as water tanks. The top of the tank is +, the bottom is -. The water level in the tank is voltage. Since both your tanks are at the same voltage, then the water is at the same level. If you connect the top of one tank to the bottom of the other, no current flows because the water level in both tanks is the same. This is wrong. This analogy would be if he connected the batteries in parallel. By connecting them in series (+ to -), the pump analogy is correct. Or, if you really want water tanks, they'd have to be stacked on top of each other so one is at a higher potential energy than the other, and their water levels ARE different. edit: to answer your question without an analogy - all you've done is make a higher voltage battery. The reason why the two batteries wouldn't "discharge" into each other is the same reason why a single battery doesn't discharge into itself - the air around it is insulating the leads so no circuit is complete. Zo fucked around with this message at 01:57 on Sep 25, 2010 |
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Sep 25, 2010 01:54
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