Kill dead air dead.Wait, what?
Connect your studio to the Main input and send the output to your transmission system. Backup audio sources might be a second computer, a looping CD player, even an iPod shuffling a playlist. In addition to audio switching, a logic output from the Failsafe Gadget can activate a device or alarm if silence is detected. Logic inputs are provided to remote the switching, or reset the Gadget.
A recessed rotary switch allows you to set the threshold of the silence sensor. Another rotary switch gives you control over the duration of the silence before the sensor takes action. Dynamic programming with a relaxed pace may want lower thresholds and longer delays, while compressed and tight programming may tolerate higher thresholds and shorter delays. The idea is to set the threshold and delay so that normal gaps and quiet passages will not trigger the sensor.
A bicolor LED gives clear status of the audio. Green is normal, above threshold. Some red flashing is normal during quiet passages and transitions, but if it stays red for awhile, a silence event is underway. A front-panel sensor bypass switch lets you put the Failsafe Gadget in manual mode; perfect for formats that only need backup during automated segments.
You can use the Failsafe Gadget in reverse too. Perhaps you have a source that you wish to put automatically on the air whenever it appears. Easy. Just feed your regular programming into the B input and this source into the A input. Place the recovery switch in the A<>B position and now whenever there is audio on your source, it will override your regular programming. Set the timer for a short delay and when the source goes silent again, your programming will resume.