Has anyone done this by using the USB 5v to trigger a small relay to send 12v+ to an amplifier when the computer is running?
Well I'm not sure the tablet I purchased will be the last tablet I'm going to use. So I would rather not open it up and hunt/peck for a 12v source to tap into. I figured using a USB port would create a modular style amp trigger circuit. The tablets DC power supply will get ACC current for charging the internal tablet battery. But to prevent any kind of turn-on thump I would rather have the amps kick on when the USB ports are activated on bootup.
dont touch the USB 5v
usb 5v is monitored and have specific current limits
there are USB controlled relays out there (becarefull though some violate usb design rules for suspend)
there is mine of course... whiuch you can purchase right here a mp3car.com (MJSG USB-IO-1)
might do more than you want...
and is controlled by front end application
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the carnetix 1900, and 2140, and the dc-dc-usb are the power supply options(there isn't many other options) that you can use for a laptop install.
ie: these replace that power brick that is included with every laptop to charge the battery.
all 3 of these options have a secondary +12v output that is designed with the intent to turn car audio amps on/off.
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Ah I understand now. Guess that is an option..