This circuit for testing old analog lines was published in April 1986 Radio Electronics magazine. The circuit uses only passive components.
One of the LM3900's four Norton operational amplifiers is used in this oscillator, which has an...
We found this circuit in Motorola's 1990 Linear Databook. The component used is unusual. The...
The components of this circuit are exchanged for modern equivalent such as 470 K for the pot and...