Audio Level Detector

[Mike Phillips]

I need an audio level detector that is functionally the opposite of a silence detector. The desired functionality is that an LED lights when there is audio present on the output of a computer sound card. While it's possible to build such a simple circuit using any number of devices, such as an LM3915 or an op-amp and a comparator, I'm asking whether someone is aware of an inexpensive kit or device suitable for the application. There are some hobby kits that might be useful (and included a printed circuit board), but I've yet to find the right one.

 

[markbohach]

I need an audio level detector that is functionally the opposite of a silence detector. The desired functionality is that an LED lights when there is audio present on the output of a computer sound card. While it's possible to build such a simple circuit using any number of devices, such as an LM3915 or an op-amp and a comparator, I'm asking whether someone is aware of an inexpensive kit or device suitable for the application. There are some hobby kits that might be useful (and included a printed circuit board), but I've yet to find the right one.

Radio Design Labs ACR 1 will do the job. Detects the audio and gives you a DPDT relay. Just wire the Normally open
contacts to a light. When audio drops below the threshold you set, the light goes out.

Wire the other set of contacts through the normally closed side and you also have a silence sensor.

You can find them on Ebay for abound $35-40 usually.

mb

 

[Mike Phillips]

Thanks

 

[BobOnTheJob]

Or for the really cheap way out, dig a small amplifier out of the junk pile & attach a diode, electrolytic and LED to the speaker output. Turn the volume up until the LED lights. Problem solved for a buck or two.

 

[Mike Phillips]

The solution was simpler than I thought. I found some LED VU meter modules on eBay for less than $10 each. Assuming they work as planned, the problem is solved.