We found this circuit with SCRs and unijunction in a Radio Electronics magazine from June 1969. The SCRs must be in accordance with the controlled incandescent lamp. The circuit is powered by DC.
This simple photometer circuit uses an LDR as a sensor and the indicator is a sensitive...
This circuit generates sinusoidal signals between 300 and 3000 Hz. We find a 303 Circuits from the 90's....
This oscillator uses germanium transistor avaialble in 1958 when the project was published....