12vdc to 5vdc adapter [Archive] - Audio & Video Forums

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Laslonimne
03-22-2011, 09:03 AM
I have a Mondial RPC-120 AC line filtration box that uses a 5 volt dc trigger on its switched outputs. My Rotel Preamp has a 12 volt dc trigger output. Can anyone point me to a 12vdc to 5vdc adapter? I'd really like to have my preamp trigger my amp et cetera to come on.

Any input would be much appreciated.

Smokey
03-22-2011, 09:45 PM
Since it is DC, you might be able to build one yourself using a network of resistor divider network. All you need is two resistors which have value of 6 to 4 ratio. I can provide more info if you like that route.

Laslonimne
03-23-2011, 05:02 AM
Thanks Smokey.
I don't really know much about electronics. I have been wondering if I could modify an iPhone car charger (12 volts in - 5 volts out) to work. But I haven't any idea what the amperage is on the trigger circuit (and can't find out from either the documentation or the web sites of the manufacturers). I think I understand that heat is a byproduct of reducing the voltage, but I haven't any idea how much we're talking about so I also haven't any idea what the risk is.

bfalls
03-23-2011, 05:15 AM
A potentiometer will perform the same task as the resistor voltage divider. I doubt very much current is required to pull the relay for the trigger. Connect the 12V +/- between the legs of the pot and adjust the pot until you read 5V between the wiper and gnd (-). After adjusting to 5V, solder your trigger wire to the wiper and ground and plug it into the component you want to trigger. Be sure to observe correct polarity.

Laslonimne
04-11-2011, 01:43 PM
My solution was an iPhone car charger. 12 volts in; 5 volts out; three bucks and a few specks of solder. Works like a champ.