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kmkcl
2 years ago

That’s about right. 1,7V is a typical forward voltage of red LEDs, 20mA is about what LEDs hold.

Depending on the LED, the 1.7V and 20mA can vary. Modern LEDs (especially SMD-LEDs) also shine quite brightly even <10mA. Other colors have other tensions (Blue for example ~3V, White 3.5V).

The invoice itself fits:

Lutz28213
2 years ago
Reply to  timigamer

Please don’t believe everything blind! The answer above is wrong – there is no voltage above the transistor.
You want ALL 3 resistances, okay? Then I still need the values of the photo diode!

karotte1386824
2 years ago

The calculation of the resistance depends on various factors such as the voltage, current and color of the LEDs as well as the desired brightness. Without these information, however, I cannot give an exact answer It would be helpful if you could provide these information to get a precise answer