This sequential tone generator circuit was found in the July 1980 issue of Radio Electronics magazine. It uses well-known integrated circuits. The tones are generated by programming resistors.
An oscillator that uses two gates is not suitable for critical applications, as it tends to pick...
We found this circuit in a 1991 Hobbyst Electronics. The circuit makes use of an unusual...
We found this circuit in a 1982 documentation. An intercom to be good must be sensitive and have...