In the figure we have a simple way to have a peak bargraph indicator. The amplifier is of the audio type, but operational ones can be used. The circuit is from Radio Electronics from March 1980.
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...