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Posts: 20 | Thanked: 0 times | Joined on Jul 2007
#61
Actually, thinking about it, it would be better to put it in parallel. That way you get the same end goal but it draws less power away from the circuit.
 
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Posts: 11,700 | Thanked: 10,045 times | Joined on Jun 2006 @ North Texas, USA
#62
Maybe another example will help those who don't get the function of a diode.

A couple of years ago I had to build a device that detected when pressure was applied to an air supply hose and started an electronic timer to accrue how long the device attached to the hose had been used. That required a timer module, pressure transducer, 9v battery, a resistor and a manual switch. But wired with those devices alone, the logic had 2 paths to take to/from the timer module (one was always "hot" due to the battery) and thus I got dual states when I only wanted one. That meant I had to place a diode on one leg of the circuit to ensure that the logic only worked along the path I intended. Once I added the diode, it worked flawlessly.

Last edited by Texrat; 2007-07-16 at 15:47.
 
Posts: 20 | Thanked: 0 times | Joined on Jul 2007
#63
Originally Posted by Texrat View Post
Maybe another example will help those who don't get the function of a diode.

A couple of years ago I had to build a device that detected when pressure was applied to an air supply hose and started an electronic timer to accrue how long the device attached to the hose had been used. That required a timer module, pressure transducer, 9v battery, a resistor and a manual switch. But wired with those devices alone, the logic had 2 paths to take to/from the timer module (one was always "hot" due to the battery) and thus I got dual states when I only wanted one. That meant I had to place a diode on one leg of the circuit to ensure that the logic only worked along the path I intended. Once I added the diode, it worked flawlessly.
That would only make sense to those versed in EE. Those who are well-versed in EE would already know what a diode does
 
Posts: 4 | Thanked: 0 times | Joined on Jul 2007
#64
Originally Posted by Texrat View Post
Maybe another example will help those who don't get the function of a diode.

A couple of years ago I had to build a device that detected when pressure was applied to an air supply hose and started an electronic timer to accrue how long the device attached to the hose had been used. That required a timer module, pressure transducer, 9v battery, a resistor and a manual switch. But wired with those devices alone, the logic had 2 paths to take to/from the timer module (one was always "hot" due to the battery) and thus I got dual states when I only wanted one. That meant I had to place a diode on one leg of the circuit to ensure that the logic only worked along the path I intended. Once I added the diode, it worked flawlessly.
wow, thnx! that makes more sense now... :P pardon my ignorance in the field of electroics... I'm just a med student
 
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Posts: 11,700 | Thanked: 10,045 times | Joined on Jun 2006 @ North Texas, USA
#65
Originally Posted by Kybo_Ren View Post
That would only make sense to those versed in EE. Those who are well-versed in EE would already know what a diode does
hey, he said it helped him, so
 
Posts: 17 | Thanked: 0 times | Joined on Jul 2007
#66
wouldnt be cool if you could supply power to the usb port then access a usb flash drive or something. that way you could store a bunch of movies and stuff on it or have multiple ones to store on them since the 2gb mmc isnt enough. does this sound feasable
 
Posts: 106 | Thanked: 11 times | Joined on Jun 2007
#67
I made the modification for my n800 and it's working 'quite' great :

- when I plug the normal power cable, it detects usb connection and unmount all my cards !
- also when I plug the usb adapter, the cards are unmounted... but I need them ! (ex : with Maemo Mapper)
Is there a way to prevent unmounting cards when you plug usb cable ? (by software configuration)

- I leave it plugged all the night(6-7hours) but it was not fully charged ?! strange...





- there is also an icon bug (the left one ; maybe normal, I never tried usb cable before) :


Last edited by murphy; 2007-08-06 at 10:08.
 
Posts: 20 | Thanked: 0 times | Joined on Jul 2007
#68
I think the easiest way to disable the unmounting would be to disable (or put a switch on) the thing that detects if there is a cable plugged in.
 
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Posts: 20 | Thanked: 0 times | Joined on Nov 2005 @ Jerz
#69
Hello all!
(been out of the 770 game for a while, but i think its time to come back)
A question in refrence to this mod...
If in addition to putting the cable in to allow the unit to charge (with diode), what if you put an additional cable (with diode) from the charger tip connector to the same conenction on the USB port? Would this enable the unit to charge from usb while also allowing power to be supplied to a USB powered device, if the wall charger is plugged in? (and no, not at the same time... but this way you would not need a switch to change between diodes?)
 
Posts: 33 | Thanked: 2 times | Joined on Jul 2007
#70
I like that idea. If you put a diode in the proper direction from the charger to the USB you could power the USB line to enable USB host mode.
Just plug the charger in when you want to use USB host mode and unplug the charger when you want to connect the USB to a PC.

Sounds like it would work great.

Expanding on that with a switch and a second diode for USB charging as well, I don't feel so good about that. Do you have a SPDT switch in mind? Where would you place it?
 
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