This circuit from a 1967 documentation generates 2.5 Hz signals depending on the capacitors used, in this case 160 uF. For 4 6700 pF the signal will be 20 kHz.
We found this circuit in the National Semiconductor Audio Handbook of 1977. The circuit produces...
This stage was used in old audio ampliiers and radios from the 1950s and 1960s. It uses one of the...
If the battery is good, the LED flashes. This simple tester uses an LM3909 integrated circuit. We found...