This circuit is from an old documentation, making use of an operational of the time. The circuit can be adapted to use modern components. The power supply must be symmetrical.
This circuit, with printed circuit board included, is from a Radio Electronics magazine from July...
In the figure we show how to excite a CMOS port by interrupting light on a Darlington...
We found this circuit in an old documentation, but it uses components that are still common in our...