This ultra-low noise amplifier and simple power supply was found in Analog Devices documentation from the 90's. The circuit can be implemented with modern equivalent components.
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....