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Home / MISC Areas / Mattel JuiceBox Power multiple JuiceBoxes from single source? Power requirements for JuiceBox

Power multiple JuiceBoxes from single source? (modified 0 times) Not_Wiggins Profile I'm working on a project to put several JuiceBoxes into a montage frame. Obviously, the device requires 4.5V to operate, but I haven't seen any information about current draw during operation. The AC adapter that is sold for a JuiceBox provides .8A If I'm looking to power 6 of them, how would I calculate the actual current I would need to supply? I would hook them up in parallel (so the voltage drop wouldn't be a problem), but am stumped on how large a power supply I need. Or, am I approaching it the wrong way? Should I assume the resistance of each device is the same and instead hook them up in series to a 27V supply at 800mA? Ideas? 09-08-2006 15:54:48

RE:Power multiple JuiceBoxes from single source? (modified 0 times) jasonharper Profile Connecting the Juiceboxes in series would be a very, very bad idea - they're not all going to present the same amount of load (especially if some are running different software, or have a different backlight brightness than the rest), and the voltage is therefore not going to be evenly distributed among them. I'd suggest using a standard PC power supply - they can certainly handle enough current that you wouldn't need to know exactly what the Juiceboxes draw. The 5V output of the supply could probably be used as is, but it might be better to put a diode in series with it (1N4001 or similar) which would drop about 0.6-0.7V (giving you the same voltage as slightly used batteries). 09-08-2006 16:19:33

RE:Power multiple JuiceBoxes from single source? (modified 0 times) WestfW Profile The AC adapter that is sold for a JuiceBox provides .8A If I'm looking to power 6 of them... Technically, if each supply is 0.8A, then for 6 in parallel (parallel IS the way to go), you'd want a 4.8A supply. However, there is probably an awful lot of conservatism built into that 0.8A value that need not be multiplied by 6. I would measure the actual current consumption, multiply by 6, and THEN add a safety factor. Startup transients are probably covered by the power-supplies ability to handle ... startup transients, so you don't need to get too fancy with the measurements. The JuiceBox contains internal regulators (it's all 3.3V internally, right?), so it can almost certainly get by with a 5V supply, which is very common. In fact, I'd probably go with this one: http://www.allelectronics.com/cgi-bin/item/PS-5372/ if my junkbox didn't yield something similar. I WOULD avoid "unregulated" wall-wart like supplies. First of all, at ~4A, you really want a switching supply just for size and weight reasons. Second, a 4.5V 4A unregulated supply is likely to put out 9V or so at low loads, which is more than I'd want to subject the internal regulators of the JuiceBox to... 09-08-2006 16:49:30

RE:Power multiple JuiceBoxes from single source? (modified 0 times) Not_Wiggins Profile Thanks for the assistance! I'm looking at doing a little of both ideas that have been put out there. I'll be picking up the 3.8A 5V supply and giving it a shot (I'll report back if there were any problems powering 6 JuiceBoxes... if not enough current, then I'll probably throttle the project back to 5), but I'm also considering trying out putting the diode(s) in-line to drop the voltage a bit. I know this question is probably an "Electronics 101"-type, but I figure I'd ask all the same: The 1N4001 diode is rated at 1A and 30A surge. Since I'll be using a 3.8A supply, would I need to create a "pseudo-diode" by hooking 4 diodes in parallel to each other and putting that package in series with the rest of the JuiceBoxes? (Basically, it'll have the .6V-.7V drop across all diodes, but the current would be distributed through them below the 1A rating). Or, is the fact that the diode is rated at 30A surge sufficient to only use one? I know... at $.59 a piece at RadioShack, I'm thinking of being conservative with the 4 diodes in parallel with each other because, heck, it's cheap. But, thought I'd ask in case I'm over-engineering that piece of the solution. Thoughts? Thanks. 09-09-2006 12:28:43

RE:Power multiple JuiceBoxes from single source? (modified 0 times) jbfan Profile by hooking 4 diodes in parallel to each other and putting that package in series with the rest of the JuiceBoxes? The diodes will not all have exactly the same voltage drop, that's the way diodes are. It may be close enough but it is likely that one diode will pass much more current than the other three - causing it to fail. A better way to go is to put one diode in series with each JB (see bad ASCII graphics below); 5V -----+----+----+----+----+----+ | | | | | | V V V V V V <- Diodes | | | | | | JB JB JB JB JB JB <- JuiceBoxes | | | | | | GND ----+----+----+----+----+----+ -J 09-09-2006 14:07:50

RE:Power multiple JuiceBoxes from single source? (modified 0 times) jasonharper Profile I've just measured about 230 mA for a Juicebox with default contrast/brightness settings, playing a music video chip. That would still be over the rating for a single 1N4001 for all six of your Juiceboxes, but you could certainly get by with two diodes (each supplying three units), especially at Radio Shack's insane prices. Or perhaps use a 1N5401, which is rated at 3A continuous. 09-09-2006 14:58:41

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