Found in National Semiconductor publication from the 1980s. This gain-100 circuit can be implemented with equivalent modern components, including lower voltage supply.
The MC15555 of this circuit is the old version of the common 555. What this circuit does is...
We find this circuit in an American 1980s documentation. The circuit can still be assembled...
This circuit triggers an LM380 oscillator, producing an audio tone with light falling on the LDR....