Found in a Popular Electronics from the 90s, this circuit activates a recorder for automatic recording of telephone calls. The circuit was used with old cassette recorders of the time.
The circuit shown in figure 1 uses the ST8R00 from ST Microelectronics which consists of a 1 A...
This is the conventional application of a 1 out of 10 decoder with CMOS 4017, as shown in an old...
We found this third-order Butterworth asymmetric filter in an old manufacturer documentation. The...