so i build digital combination lock for my projects from this website :
Digital Lab - Digital Combination Lock | Digital IC Projects | Electronics Textbook (allaboutcircuits.com)
and i added a solenoid door lock (5v) and it doesnt work. i think the problem was the current is too low to make the solenoid work.
so, how do i add more current to the output circuit? so the solenoid can work.
i tried adding more volt and it doesnt work.


thank you.

 

Instead of connecting the green LED 470R resistor to ground, connect it to the base of an NPN transistor with the emitter connected to ground. The green LED should still turn on but less brightly. Connect the solenoid between power and the transistor collector. Check that the transistor can handle the current needed by the solenoid

This uses the transistor to switch the higher current you need from the small current into its base

 

Instead of connecting the green LED 470R resistor to ground, connect it to the base of an NPN transistor with the emitter connected to ground. The green LED should still turn on but less brightly. Connect the solenoid between power and the transistor collector. Check that the transistor can handle the current needed by the solenoid

This uses the transistor to switch the higher current you need from the small current into its base

thank you for your answer.
the solenoid is now working after i added the npn transistor into the circuit.

thank you so much!