Where to find a remote activated 12v trigger relay?

My mono block amps have 12v trigger inputs to connect to another device to receive a signal to automatically power themselves on upon another device being powered on. Unfortunately none of my other audio gear has 12v trigger outputs. So my question is where can I find a gadget with 3.5mm outputs that will send out a 12v signal to my amps upon itself receiving a signal from a remote?

Currently I own this device but it too requires being sent a signal to be able to send out a 12v trigger signal: Amazon.com: Emotiva Audio ET-3 Wire Management: Home Audio & Theater

Any help is greatly appreciated. Thanks.
 
If you want a unit that will go between a previously amplified signal and your mono blocks you could consider a very high gain amplifier coupled with a time delayed circuit to detect the presence of audio.

The other approach is to use the power rails of the pre-amplifier to provide the 12V trigger.

If you Google "audio activated trigger" you'll see the general approach to this.
 
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Andolink.


First You must find out if the mono-blocks need a constant 12V or just a 12V pulse to switch and stay on. This is simply to test as long as You know how to connect there a presumably 12V DC source.
If it needs a constant 12V source, it's easy. Just activate a relay powered by the pre-amp power rails, or on / off circuit, connect this to a 12v source and voilá.
You just need it to work as a switch.


If it needs just a pulse, You can do the same, but You will need a timed delay circuit which cuts the 12V after a few ms. There are multi-function relays at electrics stores for this. Carlo Gavazzi brand comes me into mind, Alarm stores also carry similar things.
The Adapter Chrisng suggests is AC. Check with the Amp manual, if it needs AC or DC and just add a bridge and a filtering cap.
 
Or, you can just create you own switch box with a relay and a few outlets and skip the guess work about what kind of signal your amps prefer in order to be triggered by your preamp.

This box contains a 1/8" mono female jack as the input signal. This comes from a 12v wall wart that plugs into a switched outlet on my preamp and has a 1/8" male jack at the end of the cord. The 12v power drives a heavy duty 240v 30A relay with a 12v DC trigger that controls AC mains power to three outlets. The small resistor on the 12v line makes sure that the relay coil stays cool when powered up for hours at a time. The whole thing is powered by it's own AC input through the EIC inlet. The mains earth line is always connected. The Line and Neutral mains wires are both switched by the relay, so absolutely no power flows when things are switched off. The AC mains is carried inside the box by 14g solid core wire, the same wire the my house is wired with.

When the preamp is on, the outlets are active. When the preamp is off, the outlets are dead. Total cost was $30: a 12v wall wart, 1/8" male and female jacks, and a 14ga EIC cord, each from my parts box, $12 for the project box, $7.50 for three outlets, and $10 for the relay.
 

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My new pre-amp does not have 12v trigger and I need to power up 4 power amps with trigger inputs. Is there a commercial product that generates remote 12v outputs?
Niles made a current sensing outlet output 12V trigger but it is discontinued.😞

Screenshot 2022-04-27 at 22-22-50 Niles CS12V.png


Alternative is use a automatic vacuum switch outlet. plug the preamp to the Tool outlet and plug a 4ch 12VDC adapter to the Vacuum outlet to trigger the power amplifiers.

Screenshot 2022-04-27 at 22-45-16 r12vpwr1to4_1000px.jpg (JPEG Image 560 × 560 pixels) — Scale...png


Screenshot 2022-04-27 at 22-55-47 61zTJb4rO1L._AC_SL1500_.jpg (JPEG Image 1409 × 908 pixels) —...png