I'm a noob.
SITUATION: - Arduino Nano under the dash of a car. It gets 5v through a buck converter.
Required to send a 12v signal to trigger a solid state controller. Current = 75ma.
Would like to control this signal through a digital out pin (D7 is available).
I THINK THE FOLLOWING: - I can use a PNP transistor.
BASE to pin D7 through a resistor.
EMITTER to 12v side of buck converter.
COLLECTOR to load (solid state controller 75mA) which will be switched on and off from logic at D7.
PARTS: - P2N2907A : I'm not sure, this is why I'm asking
- Resistor between D7 & BASE = 10k which will flow 1.2mA which is enough to saturate?
QUESTIONS: - Is this proper?
HOW do I turn it off??? If I set D7 pin output to LOW, it will ground. But... do I set it to high? Then, the R1 resistor needs to ensure that it's big enough for the new voltage difference not to flow enough current to saturate, but sometimes the 12v is higher in a car, could be a problem? Can I somehow just set the pin to float so nothing flows?
I have seen large value resistors from base to emitter voltage, says to ensure switch turns off? Should I include this? Shown as 100k.
THANKS for any help. Trying to learn...