This circuit is from Motorola documentation, but can be implemented with virtually any phototransistor and any general-purpose transistor. The supply voltage can also be changed.
This circuit, found in US documentation, can measure the power of transmitters up to 10 W, given...
We found this circuit in an American 1980s documentation. The transistors can be equivalent as BC548...
This setting appears with variations at various points on this site. This is from a Motorola...