We found this circuit in a publication from the 1980s. Transistors can be replaced by current equivalents. The circuit is for 6 V and the capacitors determine the frequency of the oscillations.
This circuit is from a 90s Popular Electronics. It consists of a power source for bass amplifiers...
This sophisticated moving bar indicator circuit with the LM3915 is from a Radio Electronics...
This simulation shows how can we test a capacitor using a function generator and oscilloscope. The...