The presented circuit uses a PNP transistor, which can be the BC558. Observe the polarity of the supply. The circuit is suggested by Texas Instruments opto-electronic documentation.
This isolated shield is from an old documentation, making use of an operational one of the time. It...
This circuit can be used with receivers to attenuate signals that may cause interference. The...
In this circuit of an American documentation of the 90s, when the light is cut, we have the...