# Electrical – Transistor Switching for 0-5V

switchingtransistors

With a 2N3905 PNP Transistor, with base (input) and collector (output) resistances of $$\R_b=1k\Omega\$$ and $$\R_c=200\Omega\$$ (Load to Ground), connected to $$\VCC=5V\$$ and $$\GND\$$ respectively, I got $$\I_b=7.5mA\$$, $$\I_c=46.6mA\$$, $$\V_{eb}=0.91V\$$ and $$\V_{bc}=0.75V\$$ (edit. Rechecking the circuit I have $$\I_b=4.2mA\$$, $$\I_c=24.5mA\$$, $$\V_{eb}=0.85V\$$ and $$\V_{bc}=-0.76V\$$)

Hence, by switching base from $$\0\$$ to $$\5V\$$ I obtain $$\0\$$ to $$\4.85V\$$ (edit. $$\0\$$ to $$\4.91V\$$).

Is there a BJT or other transistor circuit for a better switching, closer to $$\0\$$ to $$\5V\$$, keeping the $$\200\Omega\$$ as load?

Meaning if you wanted 25mA across 200 Ohms and chose one () with 50 mOhm Rce or even 20 mOhm.
I say expensive for high volume as these are $0.65(1) instead of$0.10 but for you, cheap!