The LED frequency flashes depends on the value of the capacitor tested according to the table. We found this circuit in a Popular Electronics from the 80s.
This is the receiver circuit for the PFM (pulse rate modulation) transmitter of the previous...
This 1975 tachometer for cars with platinum can serve as an idea for new projects. The components are...
This circuit is from a publication by Newton C. Braga in the United States. The transistor can be...