Low voltage ac speaker power to trigger 12v relay

Thread Starter

Mac87

Joined Jan 30, 2023
13
I’m not very good with electronics but I have a cellular Wi-Fi camera that has a small speaker that you can talk on. I’m trying to figure out how I can use that signal to trigger a 12v relay. When I tested the speaker wire with my meter I had the meter set on 2 ac and it would only register .05 is there any way to make that trigger a 12v relay? The camera is a riolink go cellular camera. I’m trying to use the camera speaker to trigger a relay to drop a gate on a hog trap. Where I could release the gate from the camera app by talking. If I can make this work I wouldn’t have to have a second device that requires another SIM card to control the gate. Any help would be greatly appreciated
 

sghioto

Joined Dec 31, 2017
5,429
When I tested the speaker wire with my meter I had the meter set on 2 ac and it would only register .05 is there any way to make that trigger a 12v relay?
Just need an amp to boost the signal and convert to a DC voltage that can activate the relay.
 

Halfpint786

Joined Feb 19, 2018
109
You can get a DTMF decoder board on amazon for a couple bucks and route the speaker audio into that. Then just send the camera a DTMF tone. Those decoder boards have latching outputs at 5v, so you would need a transistor from there to switch the 12v to the relay.
 

LowQCab

Joined Nov 6, 2012
4,290
Audio-Triggering is going to be a "Hit-or-Miss" type of proposition.
A standard, cheap, Motion-Detector will give more reliable results,
and is much easier to implement.
.
.
.
 

Thread Starter

Mac87

Joined Jan 30, 2023
13
Audio-Triggering is going to be a "Hit-or-Miss" type of proposition.
A standard, cheap, Motion-Detector will give more reliable results,
and is much easier to implement.
.
.
.
I can’t use motion detector I have to be able to control when it’s triggered
 

Thread Starter

Mac87

Joined Jan 30, 2023
13
That's probably overkill. Are you looking to buy or build?
If I could buy something that does that I would prolly do it but if I can find out what to get I possibly could build it. I do a lot of wiring and stuff for cars but I haven’t done much with circuit boards or stuff like that
 

sghioto

Joined Dec 31, 2017
5,429
If I could buy something that does that I would prolly do it but if I can find out what to get I possibly could build it. I do a lot of wiring and stuff for cars but I haven’t done much with circuit boards or stuff like that
Should the relay activate immediately and stay activated as long as the sound is detected?
 

Thread Starter

Mac87

Joined Jan 30, 2023
13
Should the relay activate immediately and stay activated as long as the sound is detected?
It would need to activate immediately but the relay would only have to be on long enough to power the release. I use the pop lock actuator to release the gate. My other trap I have a cellular gsm box on that gate I call it and it trips a relay for 2 seconds and cuts off and that works but I’m tryin to get away from having to have 2 SIM cards on a trap (1 sim runs the gate and other sim runs the cellular camera)
 

Halfpint786

Joined Feb 19, 2018
109
What about this? I just scribbled that down, but I think it would work. Audio goes through the DC blocking capacitor and is rectified and stored with the diode and capacitor. That turns on the NPN, which turns on the PNP, and with no audio, the 10k resistor draws the capacitor back down turning off both transistors.
audio relay.png
 
Last edited:

AnalogKid

Joined Aug 1, 2013
11,199
What about this?
The input signal will need a peak value of at least 1.39 V to cause the first transistor (reference designators - !) to conduct. That is two diode drops plus the 13% attenuator formed by the three resistors.

Separate from that, there is nothing to reset the 20 uF input capacitor because it is disconnected from the resistor path to GND by the diode.

Also, the two capacitors will form a voltage (actually, charge) divider that will affect the minimum input signal needed for activation.

ak
 
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MisterBill2

Joined Jan 23, 2018
19,409
Triggering from an audio signal is by no means complex, BUT it probably will require a bit of amplifying to be reliable. The BIG CHALLENGE is that evidently the camera is outside, battery operated, and has a wireless connection. That makes the amplifier part tricky because where to put it?? two 8 pin IC devices . I have no clue as to what a "Pop lock Actuator" is or how much current it will draw. .Sending a tone instead of talking will work much better, and it certainly does not need to be a DTMF pair. Any frequency in the range from 400 Hz to 3000Hzshould work quite well.
A small voltage step up transformer, followed by a diode could turn on a transistor and operate your mechanism/gate drop. A much more advanced system will have the voltage trigger a 555 timer IC to provide a pulse to operate the release. But since we have no hint as to the power needed to operate the release no more advice.
 
Last edited:

Halfpint786

Joined Feb 19, 2018
109
Another option would be the arduino audio sensor boards. They are about the size of a quarter and have a threshhold adjustnemt. It wouldnt be too hard to adapt that to the speaker audio with a bit of attenuation. But now you are at 5v, but with that, a simple mosfet would do.
 

Thread Starter

Mac87

Joined Jan 30, 2023
13
Triggering from an audio signal is by no means complex, BUT it probably will require a bit of amplifying to be reliable. The BIG CHALLENGE is that evidently the camera is outside, battery operated, and has a wireless connection. That makes the amplifier part tricky because where to put it?? two 8 pin IC devices . I have no clue as to what a "Pop lock Actuator" is or how much current it will draw. .Sending a tone instead of talking will work much better, and it certainly does not need to be a DTMF pair. Any frequency in the range from 400 Hz to 3000Hzshould work quite well.
A small voltage step up transformer, followed by a diode could turn on a transistor and operate your mechanism/gate drop. A much more advanced system will have the voltage trigger a 555 timer IC to provide a pulse to operate the release. But since we have no hint as to the power needed to operate the release no more advice.
https://www.amazon.com/gp/aw/d/B07KD7KV4X#Ask. It’s a shaved door handle solenoid popper. When u shave your door handles off your car they pull to release the latch. On Amazon they say that it draws 35 amps. The camera is an outdoor cellular camera that’s battery powered with solar panel. What ever I add to camera to trigger a relay will have to be wired in a box to keep it out the weather.
 

sghioto

Joined Dec 31, 2017
5,429
It would need to activate immediately but the relay would only have to be on long enough to power the release.
This provides the required amplification with isolation from the speaker. Hold time is 2 seconds when the tone is silent.
Sensitivity 50mv.
1675218544817.png
 

Thread Starter

Mac87

Joined Jan 30, 2023
13
This provides the required amplification with isolation from the speaker. Hold time is 2 seconds when the tone is silent.
Sensitivity 50mv.
View attachment 286537
I just got camera out again and was testing it. I found an alarm button I didn’t realize it had. With my meter on 200 ac that’s lowest this cheap meter has. When I hit the alarm button with meter on speaker wires it went to 00.5. Being that there is a button on my phone to push to make alarm go off is there a better way to use that to trigger over the speaker wire? Does someone make a device like you drew out?
 
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