This circuit is from a 1968 Texas Instruments documentation. The components are from the time and the sensor photodiode is difficult to obtain today. The circuit has a response from 10 Hz to 20 kHz.
We found this circuit in an American documentation from the 60's. The transistors are made of...
The accuracy of this circuit depends on adjustments made with capacitors of small tolerances of known...
The figure shows how to implement an OR function with two inputs, using a relay. The relay...