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 circuit was found in documentation from the 80s. The circuit did not include resistors from...
This circuit used in instrumentation is suggested by National Semiconductor, now Texas Instruments and...
The source shown in the figure provides output voltages in the range of 1.2 to 25 V with currents up...