The photosensor integrated circuit used in this circuit is not common today. It is a device that can deliver a current of up to 50 mA at its output when fired by light. The power is from 4 to 15 V. The circuit is from a publication from the 70's.

The photosensor integrated circuit used in this circuit is not common today. It is a device that can deliver a current of up to 50 mA at its output when fired by light. The power is from 4 to 15 V. The circuit is from a publication from the 70's.