dramrattan
Member
Hi,
The 2nd circuit in the link below is what i implemented on breadboard in order to detect ringing. The LED blinks for a short period of time just visible to the eye when the phone rings the first time but for the 2nd,3rd,4th etc rings, the LED does not light or lights very very very faint barely visible to the eye and sometimes not visible at all. What could i do to keep this LED on while ringing is taking place? Or what could i do to make this LED blink visibly everytime for each ring...because i want to be able to count these rings using a PIC18F452?.
Is it to do with the RC combination formed by C2 R2? The values that i used are as follws:
C1 0.1uF,250V
C2 10uF, 250V
R1 10K
CR2 1N914
CR1 Zener 9.2V
R2 1K
LED1 Normal LED (green)
I changed the value of C2 to 33uF,250V but got no lighting of the LED and the voltage across the LED dropped from 1.4V to 0.4V so that was insuffient to light the LED...thus i put back the 10uF,250V capacitor for C2 and changed the 1K to 330 ohm but still the LED only comes on for a very short while barely visible to the eye. What to do?...I am currently reading up on the RC time constant thing hoping to find the answer.
Detecting a telephone RING 1 Electronic Circuit - CircuitsArchive
The 2nd circuit in the link below is what i implemented on breadboard in order to detect ringing. The LED blinks for a short period of time just visible to the eye when the phone rings the first time but for the 2nd,3rd,4th etc rings, the LED does not light or lights very very very faint barely visible to the eye and sometimes not visible at all. What could i do to keep this LED on while ringing is taking place? Or what could i do to make this LED blink visibly everytime for each ring...because i want to be able to count these rings using a PIC18F452?.
Is it to do with the RC combination formed by C2 R2? The values that i used are as follws:
C1 0.1uF,250V
C2 10uF, 250V
R1 10K
CR2 1N914
CR1 Zener 9.2V
R2 1K
LED1 Normal LED (green)
I changed the value of C2 to 33uF,250V but got no lighting of the LED and the voltage across the LED dropped from 1.4V to 0.4V so that was insuffient to light the LED...thus i put back the 10uF,250V capacitor for C2 and changed the 1K to 330 ohm but still the LED only comes on for a very short while barely visible to the eye. What to do?...I am currently reading up on the RC time constant thing hoping to find the answer.
Detecting a telephone RING 1 Electronic Circuit - CircuitsArchive