Hi,
I have a module which has a ground-switching input (meaning it goes high when you ground the input((it draws about 40mA at -24V)))
I am trying to control a ground signal to connect to this module using a microcontroller and 2 transistors (1 NPN one, and 1 PNP)
an I/O pin on my Microcontroller is connected to the base of a NPN transistor. The Emiter on that transistor is connected to GND. The Collector is connected to the base of a PNP transistor. On the PNP transistor the Collector is connected to the input on the "ground switching" module, and the emmitter is connected to a 5 V source.
There are various resistors in between each stage so nothing is directly connected without a resistor in between.
For some reason no matter what the module is always being triggered high, which means it's always being grounded or connected to a more positive source.
I checked the transistors and they are working. I can't seem to think of a reason why i am getting this leakage. I think it may have something to do with the fact that when i send a low signal from the MC, it leaves the base line on the second transistor (the PNP) floating, which may pick up noise and turn on, but i have a hard time finding documentation to support that.
Can anyone help please
Thanks
I have a module which has a ground-switching input (meaning it goes high when you ground the input((it draws about 40mA at -24V)))
I am trying to control a ground signal to connect to this module using a microcontroller and 2 transistors (1 NPN one, and 1 PNP)
an I/O pin on my Microcontroller is connected to the base of a NPN transistor. The Emiter on that transistor is connected to GND. The Collector is connected to the base of a PNP transistor. On the PNP transistor the Collector is connected to the input on the "ground switching" module, and the emmitter is connected to a 5 V source.
There are various resistors in between each stage so nothing is directly connected without a resistor in between.
For some reason no matter what the module is always being triggered high, which means it's always being grounded or connected to a more positive source.
I checked the transistors and they are working. I can't seem to think of a reason why i am getting this leakage. I think it may have something to do with the fact that when i send a low signal from the MC, it leaves the base line on the second transistor (the PNP) floating, which may pick up noise and turn on, but i have a hard time finding documentation to support that.
Can anyone help please
Thanks