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 use of field effect transistors in this circuit improves its performance. This configuration is from a...
This is a simple source indicated for powering low voltage projects on the bench. The circuit is...
This circuit was found in a 1969s American documentation. With modern components, it can be used...