Noise or voltage triggered relay

[adamzski]

Hello, I need a relay to be triggered from either a sound or voltage.

Could anyone help? I have very limited knowledge.

What I am trying to achieve is that when a sound comes out of a speaker a relay is tripped.

I thought I could connect a wire to the speaker then when a voltage comes through I could activate my relay or I could use something to detect a loud sound..

Cheers

 

[bjuric]

How do you want to operate a relay. Switch it for a defined period of time, switch until manually reset.....
Tapping into the speaker line might be a better option.

 

[adamzski]

Hi thanks, I want to switch it for about 3 seconds.

and yes I was thinking that going of the speaker would be easier.

 

[kak111]

I drew circuit for you, if someone will practice and count component values
in circuit.
If relay coil current > 100mA , add transistor to drive relay coil.

View attachment speaker_relay_del_out.pdf

Regards KAK