Ok ive got another question, i want just a simple LED to light up when phone line rings, couldnt i just hook an LED directly in between the red (ring), do i need a resistor so the LED dont pop? If so what size?
Yes, take a schematic page mentioned above and place LED instead of U1, keeping polarity. Thus it would work exactly as it should. You need the resistor to limit the current, you need the cap to block DC, (a ring is about 100V peak to peak at 20 Hz) and you need these zeners to make sure the circuit does not influence line during the conversation. The other small diode provides AC path for the capacitor. Discard everything on the right side of U1 if you need just an LED.
Phone Line LED
Posted - Mar 04 2003 : 4:44:14 PM
