We show an oscillator that produces rectangular TTL signals based on inverters. Inverters can also be designed with standard NOR or NAND gates. The circuit must be powered by 5 V.
Found in a Hands-On Electronics from the 90s, this circuit produces the dial tones of an old...
Found in Radio Electronics from the 90s, this circuit has several outputs with different pulse...
This circuit, found in 2002 documentation, triggers LEDs when a phone call is received. The LEDs...