Audio Activated Relay – Modification for low audio input

Thread Starter

KC2FYY

Joined Aug 24, 2019
4
How might this circuit be modified to drive it with an input audio source of less than 80mV Peak to Peak?

Possibly adding another stage with a 2N3904?

Would like to:
Keep it analog
Have a pot to adjust the input trigger level.
 

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AnalogKid

Joined Aug 1, 2013
8,154
For a signal that small, a comparator or opamp will give you much more reliable control. Are IC's allowed in the design? Is this for school?

ak
 
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