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How do you find the base resistor of an npn transistor?
To calculate the base resistor, subtract the B-E 0.7V from the driver voltage and divide by the base current: 4.5-0.7 = 3.8V / 400uA = ~9.5K ohms max. The difference in CE drop between a factor of ten and using the beta is neglible for relatively slow on/off circuits, and it lowers the driver current requirement.
How do you amplify a transistor?
This circuit uses a pair of resistors as a voltage divider to control exactly how much voltage is placed across the base and emitter of the transistor. The AC signal from the input is then superimposed on this bias voltage to vary the bias current. Then, the amplified output is taken from the collector and emitter.
Can a NPN transistor be used as a sink?
Yes. In an NPN transistor current flows from the collector, through the base into the emitter, i.e. it acts as a sink. In your circuit then, +5V from the Pi flows through the stepper motor controller, through the transistor, through to ground. The current only flows when the base is activated.
How to amplify a 0-3.3v DAC signal?
I have a 0-3.3V output that I wish to amplify to 0-10V. I am using an 8-bit R2R resistor ladder connected to a National Instruments USB-6501 digital I/O device. The application is to control a linear actuator via a controller that requires a 0-10V command signal therefore I need to amplify the output from the resistor ladder.
How does a NPN transistor work in a stepper motor controller?
In an NPN transistor current flows from the collector, through the base into the emitter, i.e. it acts as a sink. In your circuit then, +5V from the Pi flows through the stepper motor controller, through the transistor, through to ground.
Can a transistor be used as a negative switch?
However, when you connect 5v from the RPi to the + leads on the motor controller, and then use the transistor as a switch to the negative side, I’m having trouble figuring out how that is the same thing– is the circuit inside the stepper motor basically like an LED in that all we are doing is supplying access to ground to get them to turn on?