the light bulb cannot draw its rated current determined by the filament's resistance so that is why it is not lighting up on the smallest motor.
when you replaced with a bigger motors (lesser resistance in the winding) the bulb lit up because it can now draw the amount of current that bulb's filament required for it to "burn" and illuminate.
at some point In the future, are you planning on using the same circuit to show a recovery by exchanging some components?..
when you replaced with a bigger motors (lesser resistance in the winding) the bulb lit up because it can now draw the amount of current that bulb's filament required for it to "burn" and illuminate.
at some point In the future, are you planning on using the same circuit to show a recovery by exchanging some components?..

bookmark this and save yer shillings. I'll do my best to keep you on track as far as hardware goes. If you need any other ideas put to a hardware application, I'll do my best. I have been building all kinds of circuits since 1972.
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