This circuit was found in the January 1999 issue of Electronics Now magazine. The circuit uses an integrated circuit from the period and has earphone listening.
This is the circuit of a commercial analog multimeter - voltmeter, sold in Japan in the 1960s. The...
This circuit, for 78xx series integrated devices, is suggested by Motorola in its 1990 Linear...
We found this circuit in a 1972 publication. The circuit is indicated for the application of TTL...