This additional bell circuit was found in the February 1994 Electronics Now magazine. The transistors are common, and the circuit is for analog lines.
The National Semiconductor LM675 operational amplifier can provide up to 3 A of output current. In the...
We found this circuit in a 1969 Mullard documentation. The same configuration appears elsewhere in...
Found in a PE Hobbyst Handbook of 1991, this circuit was originally proposed to time photographic...