Designed for the audio track, this circuit was found in a Popular Electronics from the 90's. Other operational can be used and R7 can be 470 k. The frequency is 1 kHz.
Other operational ampliers series, such as MC34072, MC34074, MC35071, MC35072, MC35074 d MC33071 can...
This circuit is from a NEC megaphone made in Japan in the 60s. The circuit has 4 W of power and...
This benchtop AC and DC power source was published in the December 1957 Radio Electronics...