Not able to levitate magnet for magnetic levitation project
All CMOS drivers have an Ron resistance with a wide tolerance, for Vout="1","0"   

\$  ~~~R_{on}=\frac{(Vdd-Voh)}{Iol} ,\frac{V_{ol}}{I_{ol}}\$  3.3V logic family is 25 Ω, and 5V logic family is 50 Ω  ±50%

\$I_b=\frac{(V_{dd}-V_{be})}{\frac{(Vdd-Voh)}{Iol}+R_s}\$

- if using 3.3V logic which is a 25 Ohm driver
- to NPN @ 60 mA base current with specs of VBE(sat)=1.2V @ 80mA, Vbe (on)= 1V @ 10mA
- Choose Rs = 10 Ohms from 60mA=(3.3V-1.2V)/(Ron+Rs)   2.1V/60mA=35 Ohms
- driver Pd= 60mA*3.3V = 200mW shared by driver, Rs and Vbe 

- if using 5V logic which is Ron= 50 Ohm driver
- Choose Rs = 13 Ohm from 60mA=(Vdd-Vbe)/(Ron+Rs)    







simulate this circuit &ndash; Schematic created using CircuitLab