# NOT GATE, how much current can i sink?

Hey guys, i need some guidance im thinking about using a not gate, here is what im thinking...

The issue is that V out goes to another circuit that the presence of vcc will affect its function, so i assumed a diode will get the job done, also when input is high v out will sink around 12 amps am i on the right track?

You can sink as much as you like, it depends on the power supply and the transistor being used, neither of which we can see in the drawing.

The issue is that V out goes to another circuit that the presence of vcc will affect its function, so i assumed a diode will get the job done,

I don't understand this. On face value I see no reason for the diode.

Also, if this is controlling a 12A load I doubt the pullup resistor is required.

Rob

You can sink as much as you like, it depends on the power supply and the transistor being used, neither of which we can see in the drawing.
I don't understand this. On face value I see no reason for the diode.

Also, if this is controlling a 12A load I doubt the pullup resistor is required.

Rob

Yeah little vague there it was just a mock up, no values yet , i need to calculate those...

Ok so the only job of Vout is to provide ground to the circuit to witch is connected ( that has current limited circuit of 12 amps when grounded) once the signal goes high on the NPN, the diode job is because Vout connection raises and lowers voltages between 1.65v and 8v so the presence of vcc in that line will affect the behavior of that circuit.

the diode job is because Vout connection raises and lowers voltages between 1.65v and 8v so the presence of vcc in that line will affect the behaviour of that circuit.

I don't follow.

So the voltage on the "output" can vary between 1v65 and 8v. I don't see what the diode does WRT that, all it does is raise the voltage the external device sees when the transistor is conducting, you will be getting about 1v5 on that with the diode and transistor voltage drop.

EDIT: Oh I think I get it, you are worried about VCC appearing on the output. Firstly it's through a resistor so probably not an issue depending on the relative impedances, but why is the resistor there in the first place.

I think we need more details of this external device.

Rob