Automatic switching between two power sources

-

hi

i have project gets power car battery or 12v wall wart.  i'd have both of these wired in, when mains power present, have battery no longer supplying.  battery , mains supply going kept independent, no charging occurs, , i'd make automatic battery can kick in ups.

is simple using p channel mosfet wall-wart output gate turn off battery supply, , adding diode @ both supplies neither can feed power other?  or there other issues need consider?  presumably since mosfet switched voltage can put large value resistor before gate ensure low power consumption switching?  also, 12v split run devices directly, microcontroller , supporting ics via switched mode 12-5v dc-dc converter - there issue 1 of interfering concept?

thanks in advance advice,
geoff

it sounds have ruled out diode oring them together. relay, powered wall wart easiest. opto-isolator control fet, or maybe switch battery off, if current isn't high. protected high side load switch easy control wall wart voltage, (http://www.fairchildsemi.com/ds/fd/fdc6324l.pdf) though many others make similar parts.


Arduino Forum > Using Arduino > General Electronics > Automatic switching between two power sources


arduino

Comments

Post a Comment

Popular posts from this blog

Thread: PKI Client 5.00 install (for eToken Pro)

-
my company uses aladdin etoken pro authentication on vpn connections. etoken requires pki client application on client machine before os recognize it. app , token work fine on xp, use ubuntu on laptop. aladdin has offered linux version of client, rpm. convinced our internal guys rpms, , i've been trying work couple days. begin with, hp pavilion dv4-1435dx laptop running jaunty 64-bit. - started out converting .rpm .deb using alien: code: sudo alien -d pkiclient-5.00.28-0.x86_64.rpm - worked fine , got nice little .deb - next, ran .deb install client: code: sudo dpkg -i pkiclient_5.00.28-1_amd64.deb - , executed without errors/issues. pdf rpm said there should launcher @ applications > etoken > start etoken pki client, didn't exist. figured might because installed deb instead of rpm. bounced box, still wasn't there. no big deal... - install network manager can configure vpn connection use token: code: sudo aptit...
Read more

ATmega2560-Arduino Pin Mapping

-
hi community, in last days working on project using arduino mega 2560. on planning pin using found bugs in atmega2560-arduino pin mapping . if right there labels (such pwm) in 'mapped pin name' @ wrong row ( mixed pin numbers right one...) in attachment openoffice calc , pdf file corrected table. ( hope ;-) ) i post here tab separated table : code: [select] arduino mega 2560 pin mapping table atmega 2560 pin out arduino mega function nr name function function function mapped pin name function function datasheet 1 pg5 oc0b digital pin 04 pwm 2 pe0 rxd0 pcint8 digital pin 00 rx0 (usart0 receive pin, programming data input or pin change interrupt 8) 3 pe1 txd0 digital pin 01 tx0 (usart0 transmit pin or programming data output) 4 pe2 xck0 ain0 (usart0 external clock  input/output) 5 pe3 oc3a ain1 digital pin 05 pwm 6 pe4 ...
Read more

Crossfader Arduino Tutorial

-
hello i'm super newb please don't bash me much. i'm using led's , i've connected them correctly (finally) , wondering why program here ( http://www.arduino.cc/en/tutorial/colorcrossfader ) doesn't work? say's haven't declared crossfade. read directions on top , said crossfade needs used list order of colors. isn't declared in main part (void loop() )? or need declared before? nevermind void on bottom , needed before voidloop. lol anyways playing rgb led's wondering if has specific way of making them fade in , out different colors? (brightness , color mixing) code: [select] /* * code cross-fading 3 leds, red, green , blue (rgb) * create fades, need 2 things: *  1. describe colors want displayed *  2. list order want them fade in * * describing color: * color array of 3 percentages, 0-100, *  controlling red, green , blue leds * * red red led @ full, blue , green off *   int red = { 100, 0, 0 } * dim white 3 l...
Read more