LPTEL, telephone ringer repeater, light bulb, Amedeo Valoroso, SIP, telecom, telephone line

LPTEL, telephone ringer repeater

LPTEL is a phone ringer repeater: it turns on a light bulb when the phone is ringing. It connects to the telephone line, so it is independent of the telephone. Phone ringer repeater, R1 components – resistor 47 ohms 1/4 WC1 – [...]

SPTEL, sip line detector engaged, assembly, Amedeo Valoroso, busy telephone line indicator

SPTEL, committed phone line indicator

SPTEL is a busy phone line detector, which I designed when I was just over 15 years old: it is an LED that lights up when the phone line is engaged by a telephone in conversation. This my [...]