TIP120 is not available in local stores, instead i found TIP122. On other forums i read that this alternative can work by changing resistor value. Can you please confirm if I can ise TIP122 and what changes i will have to do in circuit diagram?
Also IRF9Z24N is not available in local stores, what alternative can i use for same?
TIP122’s can be used and can be used with the same resistor or a smaller one to get better saturation (150 – 180 ohm).
I’m not at home and don’t have the information on the IRF9Z24N with me, but this was chosen primarily due to the low RDS(on) value. The requirements are not too great, P-channel, 5V, and low amps. So any similar mosfet will be suitable.
It should be noted that I include the IRF9Z24N as a why to prevent reverse voltage which I think is a problem due to using Nano clones (I buy the very cheapest possible). You can also use a diode like a 1N4001 but this has a higher voltage drop of about 0.7v – 1.0v.
Thanks for quick reply, Till i get correct mosfet, what if i don’t add mosfet / diode for the moment, and take care to not connect external power supply when USB is connected (and vice versa). So can I skip mosfet / diode if such precaution is taken?
Although not in time to help you, I will try to put together a list of alternative components. The next iteration of the dropController is likely to use mosfets rather than TIPs. I really only used TIPs because I had a lot of them.