How does an audio activated relay switch work?
When the two 1N4148 diodes receive an audio signal through the 1uF capacitor then they convert this audio signal in to DC signal and send it to the base of the transistor due to which the transistor become switch ON and activates the relay. 1N4001 diode across the relay is used to safe the transistor from the back EMF of relay.
Do you need an audio signal for a relay?
This little circuit can save a lot of power and also it is ideal for battery operated projects. The circuit requires a small audio signal to switch on the relay such as equal to the audio output of a headphone jack of any equipment.
How many relays are on a skrodahl audio switch?
That is the philosophy that lies behind [Skrodahl]’s relay-based audio switching board, which boasts 5 high-quality relays each handling a stereo input, with their control passed either to a rotary switch or to an ESP32 module.
How many volts does a headphone relay need?
The circuit requires a small audio signal to switch on the relay such as equal to the audio output of a headphone jack of any equipment. The circuit can be operated with 12 volt DC but you can also operate it with 5, 6 or 9 volts, make sure to use the relay according to the voltage.
How does a speaker relay work on a cell phone?
Typical cell phones supply around 3 volts to the motor so just look for a relay that works at that voltage. The other option would be to run the speakers input wires through a bridge rectifier and convert the sound signal to DC and use that to power the small 3 volt relay. Does triggering the relay have to work multiple times or just once?
How to trigger alarm with relay from PC sound output?
The background is the following: a Mac-mini collects, by means of different computer programs, alarms from different sources. in order to make the sound signal loud enough, a simple possibility would be to plug a hifi-system on the sound output of the PC, and set the volume to its maximum.