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Photo Forum / Digital Photography / Digital Photo / February 2005How to build Powershot A85 Power supply?
Has anyone built their own DC power supply for an A85? With four AA, it would need to be 6 volt but what amperage? What is the pin configuration, center + or -? Thanks > Has anyone built their own DC power supply for an A85? With four AA, it > would need to be 6 volt but what amperage? > > What is the pin configuration, center + or -? > > Thanks Amperage is around 2-2.5 amps for digital cameras. Why built one. You can buy regulated power adapters for $20-30. Here is a universal ac adapter for Digital Cameras. About $30. http://www.digipowersolutions.com/show_product.php3?pid=100817&Group=AC+Adaptors &Type=A80&Manuf=CANON&subgroup= Radio Shack has one(if you can find it): Catalog #: 273-1696 http://www.radioshack.com/searchsku.asp?find=273-1696  SignatureCSM1 http://www.carlmcmillan.com -- Would that one work on a powershot a400? I already have an adapter with a ton of jacks, it says right on the adapter what the voltage levels can be set at (multiple levels) but how could I tell if it'd provide the right amperage? I'm not super-knowledgable about electrical circuitry, just enough to know that there is more to a given source of DC than voltage (pressure of electrons) but also amperage(volume of electrons at a given voltage). Any informed opinions gratefully accepted. >> Has anyone built their own DC power supply for an A85? With four AA, it >> would need to be 6 volt but what amperage? [quoted text clipped - 13 lines] > Catalog #: 273-1696 > http://www.radioshack.com/searchsku.asp?find=273-1696 If the power adapter can supply up to about 2 amperes of current and is voltage regulated for the voltage that is set, then it is safe to use on just about any digital still camera. (you just have to find the power plug that fits and has the correct polarity) DO NOT use a power adapter that is NOT regulated. The camera will only draw as much current as needed. A power supply with a larger current capacity is necessary over a power supply that does not have enough current capacity. If the power supply does not have enough power (current), the voltage will drop to a level too low for the camera to work correctly. By the way there is another universal power adapter. http://www.bizrate.com/buy/products__att259--221062-,cat_id--46011.html The important things to know about power for digital cameras is Voltage, Current and Polarity. Volt defined: The volt is the practical unit of electromotive force (emf), or electric potential. It is that potential which will cause a current of one ampere to flow through a resistance of one ohm. SignatureCSM1 http://www.carlmcmillan.com -- > Would that one work on a powershot a400? > I already have an adapter with a ton of jacks, it says right on the [quoted text clipped - 22 lines] >> Catalog #: 273-1696 >> http://www.radioshack.com/searchsku.asp?find=273-1696 Hah! I finally found it. OK, on it it says --- PLUG-IN CLASS 2 TRANSFORMER "MW Switching Universal Power Supply", made in China, and a Canadian Underwriters Lab Symbol Model MWS1189UC Input 100V-140V, AC 60Hz, 28W Output: 3, 4.5, 6, 7.5, 9, 12v DC. Current 1700 mA -I have a voltmeter and I tested some NiMH batteries that were rated at 1.2V (much to my surprise, I had assumed they were 1.5V, but I got home and looked at the package and it said 1.2V) right after I finished charging them, and they were in fact, only putting out 1.2V when hooked up to the large resistance associated with a voltmeter, when they were connected to an actual load of much lower resistance, I'm sure their V would be even less --- my point in all this being that even if my adapter is rated at 1700mAh, don't you think the camera could handle it anyway (especially if I turned the LCD screen brightness way down) because it clearly can handle batteries that put out significantly less than 1.5V? (sorry, long question) -Does the fact that this adapter states a current at all, indicate that it is 'Regulated'? -A lot of these NiMH batteries have ratings like 300mAh, or the highest I think was 2300mAh --- does this kind of rating mean basicaly that for the first hour of use, at the rated voltage of 1.5V, they put out that average amount of current (because it would vary, wouldn't it, somewhat anyway as the battery depleted itself)? -If a NiMH battery was rated at 300mAh does that mean it puts out an average of 300mA/hour at the rated voltage of 1.5V, over it's lifetime? > Hah! I finally found it. OK, on it it says --- > [quoted text clipped - 28 lines] > -If a NiMH battery was rated at 300mAh does that mean it puts out an average > of 300mA/hour at the rated voltage of 1.5V, over it's lifetime? The Adapter may or may not be regulated, If it does not say I would test the adapter before using it on my digital camera. Select 6 volts, measure the power supply without a load (leads open), note the voltage (it must be 6 volts +- 5%). To put a 1700 mA load at 6 volts you would need a 35.29 ohm resistor, but since the closest standard value is 36 ohms, use a 36 ohm, one watt or more resistor. The resistor will get very warm (hot to the touch). Put power supply and the volt meter across the resistor to see if the voltage stays at 6 volts. If the voltage does not drop more than 5%, it is regulated and safe to use on a digital camera. (5% drop from 6 volts = 5.7 volts) However 1700 ma is very close to the minimum current capacity for supplying a digital camera. Not using the LCD will conserve the most power. If there is an optical viewfinder, use that to frame the picture. Be conservative with flash use also. On NiMH batteries, when fully charged the voltage is about 1.3-1.4 volts no load. Nominal voltage is 1.25 volts. (they get better with some use) The MaH rating is based on supplying the rated current for one hour before dropping to some stated minimum voltage (around 1 volt). A fully charged 300 mah battery with supply 300 ma for one hour until the voltage is around 1 volt. (It would keep outputting some current until the battery is dead). Digital Cameras have a power protection built-in that shuts down the camera at some minimum voltage. You want the highest Mah rating you can find for the best price. The higher the Mah the longer the batteries will operate the camera. For Digital cameras, the minimum I would use is 1600 Mah. SignatureCSM1 http://www.carlmcmillan.com -- I must not be understanding something properly (please be patient, I'm not very technicaly oriented ).: -if a battery rated at 300mAh only provides 300mA, how is it possible for a 300mAh to power one of these cameras at all? Given that the camera needs minimun 1700mA( I thought that was what you said, no? Different context maybe), and the battery only puts out 300mA? Yet it has been my experience that these 300mAh batteries will run a digital camera, just not for very long. >> Hah! I finally found it. OK, on it it says --- >> [quoted text clipped - 76 lines] > the Mah the longer the batteries will operate the camera. For Digital > cameras, the minimum I would use is 1600 Mah. Question: Will a 300 mah battery power a digital camera? The short answer is not for very long. A 300 mah battery will supply 1700 ma for a very short time. About 10-11 minutes. As long as the voltage is present, the load will draw as much current as demanded. If the camera looks like a 3.5 ohm resistor to the 6 volt battery, the battery will try to supply 1700 ma. (It is Ohms law) Ohms law is voltage divided by resistance in ohms equals current in amps. E/R=I where E is Voltage, R is resistance in ohms and I is current in amps. What happens with batteries, the voltage drops with the more load put on it. You would not want to put a short on a strong battery, such as your car battery, it will explode. Use 1600 mah or more. A 1600 mah battery will supply 1600 ma for one hour until the battery voltage drops to around 1 volt. 1600 ma = 1.6 amperes. A 2300 mah battery = 2.3 amperes for one hour. At 1700 ma load, it will last longer. I miscalculated the resistor to test the power adapter. Use a 4 ohm 10 watt wire wound resistor. SignatureCSM1 http://www.carlmcmillan.com -- > I must not be understanding something properly (please be patient, I'm not > very technicaly oriented ).: [quoted text clipped - 85 lines] > > the Mah the longer the batteries will operate the camera. For Digital > > cameras, the minimum I would use is 1600 Mah. I made a big miscalculation on the resistor needed to test the power adapter. I said one watt, but the correct wattage is 10 watts. The resistance is 6/1.7=3.529 ohms. (1700 ma=1.7 A) For a 10 watt wire wound resistor the nearest standard value is 4 ohms, so 6 V/4 ohms=1.5 or 1500 ma. 6 volts times 1.5 A = 9 watts. SignatureCSM1 http://www.carlmcmillan.com -- > > Hah! I finally found it. OK, on it it says --- > > [quoted text clipped - 67 lines] > the Mah the longer the batteries will operate the camera. For Digital > cameras, the minimum I would use is 1600 Mah. OK, I'm going to try to dig up a 4ohm resistor. Would you verify the color codes? I believe for a 4 Ohm resistor, the bands would be yellow, black, gold, brown. with the last band indicating tolerance, not that critical in this case. I don't even know if I've got one, but are those the right bands --- CSM1? >I made a big miscalculation on the resistor needed to test the power > adapter. I said one watt, but the correct wattage is 10 watts. The [quoted text clipped - 96 lines] >> the Mah the longer the batteries will operate the camera. For Digital >> cameras, the minimum I would use is 1600 Mah. You made me think, it has been a long time since I read color codes. Black Yellow Black 1st band Color is on one end of the resistor. Read Left to Right. First significant figure Black is 0 Second significant figureYellow is 4 Multiplier Black is 1 Fourth band is tolerance. Gold = 5% Silver=10% No color= 20% Values of less that one ohm then use the multiplier of Gold = 0.1 and Silver=0.01. Which is Gold divide by 10 or Silver divide by 100. 10 Watt wire wound resistors usually do not have color codes. The value is printed on the light brown square. SignatureCSM1 http://www.carlmcmillan.com -- > OK, I'm going to try to dig up a 4ohm resistor. Would you verify the > color codes? [quoted text clipped - 111 lines] >>> the Mah the longer the batteries will operate the camera. For Digital >>> cameras, the minimum I would use is 1600 Mah. There are no bands on a 10W resistor. The rating is printed on the side or top. If you require 10 Watts if actual power, a 25W resistor would last much longer, not burn up as quickly, disapate the heat better (run cooler to the touch). Yes a 10W resistor is capable of disapating 10watts but only at it's maximum rated temperature that will burn you if you touch it. Remember that the power is proportional to the square of the appplied voltage and even a slight voltage fluctuation can push the power over the rating quite easily. > You made me think, it has been a long time since I read color codes. > Black Yellow Black [quoted text clipped - 129 lines] > >>> the Mah the longer the batteries will operate the camera. For Digital > >>> cameras, the minimum I would use is 1600 Mah. I have a 4.7 ohm 2 watt resistor. The color bands are yellow,violet,gold. So the bands for 4 ohms would be yellow, black,gold. Or they could be black,yellow,black. SignatureCSM1 http://www.carlmcmillan.com -- > OK, I'm going to try to dig up a 4ohm resistor. Would you verify the color > codes? [quoted text clipped - 103 lines] > >> the Mah the longer the batteries will operate the camera. For Digital > >> cameras, the minimum I would use is 1600 Mah. Black, yellow, black isn't used in standard colour codes > I have a 4.7 ohm 2 watt resistor. > The color bands are yellow,violet,gold. [quoted text clipped - 126 lines] > > >> the Mah the longer the batteries will operate the camera. For Digital > > >> cameras, the minimum I would use is 1600 Mah. It has been years, I did not remember that the Gold and Silver multiplier is used below 10 ohms. I though it was one ohm. SignatureCSM1 http://www.carlmcmillan.com -- > Black, yellow, black isn't used in standard colour codes > [quoted text clipped - 143 lines] > > > >> the Mah the longer the batteries will operate the camera. For Digital > > > >> cameras, the minimum I would use is 1600 Mah. Precision resirtors are printed text on the side. I believe precision resistors can be ordered custom made or from a big supplier in any value desired for not too bad a price (a few years back). The time wait for them is brutal though. > It has been years, I did not remember that the Gold and Silver multiplier is > used below 10 ohms. I though it was one ohm. [quoted text clipped - 157 lines] > Digital > > > > >> cameras, the minimum I would use is 1600 Mah. Ok, well it looks good, actually. I found a resistor that didn't have color bands on it, but was red, and had 4R(7 or Z couldn't tell), and +-5% on the other side. Since it is only necessary to hook it up momentarily to a low voltage I wasn't that worried about heat dissipation capacity. I checked the R with my multimetere and it showed exactly 4 Ohms of resistance. Then I set the adapter at 3V, with no load but the meter, and tested --- it showed exactly 3V, to within a hair actually. Then I put the resistor in parallel with the meter and it showed exactly the same voltage, no perceptible drop. And I know I had good connection with the resistor becaue, boy, did it ever get hot --- in the two seconds that power was applied, it got too hot to touch and I could smell the 'hot component' smell! No smoke, but next time I do something like this I'll pay more attention to power ratings, I think. So there doesn't seem to be a problem with the adapter supplying enough amps to a the camera, is there any way to ensure it won't push too much? No, I guess not because you said that the camera will only take what it needs, right? The only potential problem was that it couldn't supply ENOUGH amps, and the voltage would sag(if I have it right), if it wasn't regulated. Now there's another problem with using this adapter, which is that not one, out of the dozen or so jacks that came with the adapter, fits the DC In receptacle on the camera. I'll go hunt around 2nd hand shops and see what I can find. How's my methodology here, guys? Am I making any glaring mistakes? > Precision resirtors are printed text on the side. I believe precision > resistors can be ordered custom made or from a big supplier in any value [quoted text clipped - 186 lines] >> Digital >> > > > >> cameras, the minimum I would use is 1600 Mah. That was probably a good enough test. Since the voltage did not change from no load to half full load, the power supply is regulated. The next most important thing is to get the polarity correct. Look closely at the symbol next to the power connector on the camera, it should have the polarity marked. Use a magnifying glass to see the + or - symbol in the center of the semicircle. Wire a connector to the power supply that fits the camera. Make sure the polarity is correct for the center connector of the plug. Put the power supply on 3 volts and DO NOT change to any other voltage. The A400 uses 2 AA batteries, so the voltage required is 3 volts. It would be a good idea to put tape on the voltage switch, so that it does not get changed accidentally. Be brave, try it on the camera. If you want to buy the ACK 800 AC adapter kit, click this link. I have seen it for $30 at amazon.com. http://www.google.com/froogle?q=AC+adapter+kit+ACK800+&btnG=Search+Froogle SignatureCSM1 http://www.carlmcmillan.com -- > Ok, well it looks good, actually. I found a resistor that didn't have color > bands on it, but was red, and had 4R(7 or Z couldn't tell), and +-5% on the [quoted text clipped - 212 lines] > >> Digital > >> > > > >> cameras, the minimum I would use is 1600 Mah. There is no polarity switch, you alter the plug's polarity by how the plug connects to the cord, it has 2 identical prongs that go into 2 identical receptacles and depending on which prong goes into which hole the polarity of the plug is determined --- point taken, though. I'll tape it. So, if it goes bang and fills the room with evil plastic-smelling fumes, you'll buy me another one, right? (joke) I'll let you know what happens, but first I have to find a plug. > That was probably a good enough test. > [quoted text clipped - 279 lines] >> >> Digital >> >> > > > >> cameras, the minimum I would use is 1600 Mah. "4R7" is the standard way of rating resistors in ohms. Back in about 1976 the standards committees decided to replace the decimal point with "R" to make diagrams and components more readable. "K" replaces "kilo" and "M" replaces "Mega" etc... 4K7 would be 4700 ohms and 3M125 would be 3.125 megohms. > Ok, well it looks good, actually. I found a resistor that didn't have color > bands on it, but was red, and had 4R(7 or Z couldn't tell), and +-5% on the [quoted text clipped - 212 lines] > >> Digital > >> > > > >> cameras, the minimum I would use is 1600 Mah. http://www.gizmos2go.com/xcart/customer/product.php?productid=3561 Here's an example of a universal AC adapter for only $10.88. Now it says its for a digital camera. Is there a chance its not regulated? Put a load of 1/4th that of your device and measure the voltage. rplace with the device and measure. If they're equal - it's regulated! No other way? I don't have a voltmeter....... > Put a load of 1/4th that of your device and measure the voltage. rplace with > the device and measure. If they're equal - it's regulated! Plug your camera in and if you get smoke, the power supply is not regulated. You take a big risk, not knowing. The label will say regulated or stabilized if it is. If the label does not say, it probably is not. Take the power supply to a electronic repair shop (TV shop) and have the tech check it. SignatureCSM1 http://www.carlmcmillan.com -- > No other way? I don't have a voltmeter....... > > > Put a load of 1/4th that of your device and measure the voltage. rplace with > > the device and measure. If they're equal - it's regulated! Not really true about the regulated. Most won't say since they are OEM specific. > Plug your camera in and if you get smoke, the power supply is not regulated. > [quoted text clipped - 11 lines] > with > > > the device and measure. If they're equal - it's regulated! |
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