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Posts: 46280
Location: USA
Joined: June 22, 2001
Contributor
Since: February 2, 2002
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A 12v trigger can be added a few different ways but in some cases it involves a bit of internal modification. Here are a few ideas.... 1): If the amp / preamp / receiver / has a switched AC outlet on the back of it's chassis as some do, you can just plug a 12vdc wall wart into the switched AC outlet and you now have a 12vdc trigger source. Connect the output of the wall wart 12vdc to the trigger input of the device you want to control. However, it usually isn't that simple as most 'high-end' gear do not have switched AC outlets behind the chassis.... but some receivers and integrated amps do. 2): There might already be a 12vdc source inside the preamp, possibly for panel lighting. Tap off that source and run it out as your 12vdc trigger. If that 12v source is AC instead of DC, create a 1/2 wave rectifier using a small silicon diode and add a small cap for filtering. Most 12vdc trigger circuits require very little current so the chances of over loading the existing 12vdc source in the preamp is pretty minimal. 3): Find the primary side of the power transformer inside the preamp and determine how / where the AC mains power is applied to it. Wire the AC primary side of a small 12vdc power brick to the primary side of the power supply transformer and you now have a 12vdc trigger. Or build a small 12vdc power supply within the preamp chassis using a small transformer, rectifier diode, and filter cap. *If noise from a switching power supply based wall wart or power brick is a concern, get one that is 'linear' instead of 'switching'. The wall wart or power brick doesn't need to source a lot of current. It will vary depending on the number of devices you want to trigger. I'd say anything over a hundred mA or so will be fine. I'd get a 500mA or 1Amp 12vdc wall wart / power brick but it's not at all critical. 4): Create a totally separate remote controlled 12vdc trigger: - Use one of those AC outlet remote controls available at many hardware stores, Target, or Amazon. Plug a 12vdc wall wart into it and you now have a remote controlled 12vdc trigger source.
 
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