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.
We found this circuit in a year 2000 documentation. It must be powered by a voltage of 5 V as it...
This circuit was found in the February 1990 issue of Radio Electronics magazine. The circuit uses...
Voltage comparators, such as those in the LM139/239/339 series, consist of devices that can be...