I've read many descriptions of how transistors work but apart from understanding that the current flow is reversed, I just don't get why or in what circumstances one would use either type.
Is the following correct ?
For a PNP transistor to turn on - used as a simple switch - the voltage at the base must higher or equal to the voltage at the base
For an NPN transistor to turn on - used etc - the voltage at the base must be LOWER than the voltage at the emitter
So, with an NPN with 12v at the base and 12v at the emitter its off but when you drop the voltage down to say three volts on the base it turns on. With a PNP with 12v at the emitter and 12v at the base its hard on. Drop the base voltage down to 3v and it turns off.
I apologise for apparently trivialising such a wonderful object, but I really do want to start to understand and my simple mind works best with the kind of 'which means that' simplicity of everyday life...
Please be gentle with me!
Is the following correct ?
For a PNP transistor to turn on - used as a simple switch - the voltage at the base must higher or equal to the voltage at the base
For an NPN transistor to turn on - used etc - the voltage at the base must be LOWER than the voltage at the emitter
So, with an NPN with 12v at the base and 12v at the emitter its off but when you drop the voltage down to say three volts on the base it turns on. With a PNP with 12v at the emitter and 12v at the base its hard on. Drop the base voltage down to 3v and it turns off.
I apologise for apparently trivialising such a wonderful object, but I really do want to start to understand and my simple mind works best with the kind of 'which means that' simplicity of everyday life...
Please be gentle with me!