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


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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.

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.

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.

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.

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.