Am posting here due to disappearance of the projects forum.
I need to be able to turn on a motor for 10 minutes or so per day. I've extracted an LCD programmable digital timer out of a mains switch and can run this on a single AA battery 1.2 to 1.5v. The control line is 0V when OFF and 1.5V when ON.
I'd like it when ON to power my 3-6V motor which draws about 50mA free running and about 800mA at stall @ 5V.
I have gone to various websites to understand what NPN transistor I should use and also what base resistor to use but my calculations don't tally around hFE etc.
Current - should I be looking to have the transistor collector current >=800mA ?
Voltage - is it OK to have 1.5V on base and say 5V on collector?
Base resistor - I presume I need this to reduce the current through the timer and base? Any suggestions please around what value to use?
Capacitor - should I use a capacitor to "buffer" the motor current draw on startup?
Grateful for any help at all.
Thank you.
Matt
I need to be able to turn on a motor for 10 minutes or so per day. I've extracted an LCD programmable digital timer out of a mains switch and can run this on a single AA battery 1.2 to 1.5v. The control line is 0V when OFF and 1.5V when ON.
I'd like it when ON to power my 3-6V motor which draws about 50mA free running and about 800mA at stall @ 5V.
I have gone to various websites to understand what NPN transistor I should use and also what base resistor to use but my calculations don't tally around hFE etc.
Current - should I be looking to have the transistor collector current >=800mA ?
Voltage - is it OK to have 1.5V on base and say 5V on collector?
Base resistor - I presume I need this to reduce the current through the timer and base? Any suggestions please around what value to use?
Capacitor - should I use a capacitor to "buffer" the motor current draw on startup?
Grateful for any help at all.
Thank you.
Matt