Solar timer (CB20498E)

This very low consumption circuit can be powered by a solar cell. The time indication is given by a microammeter.

Simple Microphone Preamplifier (CB4768E)
This circuit was found in a Popular Electronics of the 90s. The output amplitude will be between...
555 Sequencer (CB3981E)
This circuit generates sequence of pulses in order and times determined by the capacitors in pins...
8 Channel Encoder with 4017 (CB4530E)
This circuit was obtained from an English magazine from 1979, but can be easily assembled today...