This interesting circuit found in American documentation generates a busy signal, without you having to take the phone off the hook if you do not want to answer. The components used are common.
The circuit shown in the figure serves as a pre-amplifier with a voltage gain of around 12 times,...
Based on Texas Instruments documentation, this circuit serves for sensor interfacing. The circuit is...
This article is from a publication by A. Fanzeres from the 70s. We kept the original text. This...