ring detection circuit

[summersnow]

ring detector circuit

I have a problem here.
i tried to build a ring detection circuit.
But when i connect the ring and tip of the telephone cable to this circuit,i found out that it automatically being off hook.
As a result,it cant be used to detect the ringing signal and it get engaged when i call to the telephone.
Is there anyone who can explain to me why it get off hook even there are no ringing signal?
Thanks in advance

 

[rogerynt]

Hi,

Please try this circuit. It works well for most European countries.

Var1 : varistor. For protection purpose.
L5, L6 : for EMC purpose. Avoid unwant signal radiates out through telephone line.
K3010 : Bidirection photocoupler. For line reversal only. You can keep on use your current photocoupler.

Roger

 

[siongboon]

telephone ring detection circuit

I have a similar ring detector as yours.
It works perfectly.

Maybe you would like to take a look for reference,
**broken link removed**