I'm having some trouble working out the correct value for a base resistor to use with an NPN transistor. I've tried researching it but I've come across so many different calculators and formulas that I'm completely confused!
What I need to do is use the transistor as a switch. I'm using a PICAXE IC's output to turn the transistor on/off. The transistor is then to be used to turn on/off a bluetooth module that requires 40ma. (a picaxe can only output 20ma max from one of it's pins apparently)
I have some BC847B transistors to use, the datasheet of which can be found here: http://digichip.ru/datasheet/PDF/64...60af35bde9ebd8f01f492dc059593c/BC847BT116.pdf
The circuit is operating on 4.5v.
Any help would be greatly appreciated, thank you for your time and let me know if you need any additional details from me.
What I need to do is use the transistor as a switch. I'm using a PICAXE IC's output to turn the transistor on/off. The transistor is then to be used to turn on/off a bluetooth module that requires 40ma. (a picaxe can only output 20ma max from one of it's pins apparently)
I have some BC847B transistors to use, the datasheet of which can be found here: http://digichip.ru/datasheet/PDF/64...60af35bde9ebd8f01f492dc059593c/BC847BT116.pdf
The circuit is operating on 4.5v.
Any help would be greatly appreciated, thank you for your time and let me know if you need any additional details from me.