Simple transistor question

[edmunds]

Dear all,

Am I right thinking that while NPN transistor switch configuration will reverse the logic (i.e. if I input high, I will get low between the collector and VCC and VCC for low input), two of these buggers i.e. NPN darlington pair should reverse each other and give me a true switch so my load will be on, when I input high, right?



Thank you for your input,

Edmunds

 

[bluejets]

That's a darlington arrangement, not what you want I believe.

 

[edmunds]

That's a darlington arrangement, not what you want I believe.

Thank you. In other words, this won't do it. The TR2 would have to 'go up' (base to collector?) in the schematics above for this to happen?

Edmunds

 

[edmunds]

Thank you, got it.

Edmunds

 

[eggdweather]

You could also use that circuit but change the logic by moving the load connection to the other relay connection.