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.
This power supply is based on the 723 integrated circuit, which is no longer very common today. The...
This siren configuration using the 555 has already been explored in other circuits on this site. In...
The values of the capacitance between output A and ground can be programmed digitally in 18 steps...