Tarkus
Newbie level 3
I've spent the last few months teaching myself electronics and I've come to an impasse; a few things I can't seem to figure out. If anyone can answer any of my questions, I'd be very appreciative.
Any help is appreciated
- 1. I'm trying to make a motor run from the output on a microcontroller. The output from a microcontroller will be linked to either a transistor or an opamp in order to drive the motor. what would be the simplest way to allow the DC motor to reverse polarity (thus changing the direction of the rotation)
Currently I put the motor in series with the opamp, which switches between 0V and 5V but a short circuit occurs when I try to connect the terminal to both the + and - rails. I put resistors on each but the motor doesn't seem to recieve any voltage. I'd like to use as few parts as possible because this may become a solar powered project. Also, the motor never stops, it only goes forward and reverse.
Summary: I'm trying to make a small DC motor move and change directions based on the output of a microcontroller.
- 2. Since I've been working with microcontrollers and logic chips. Let's assume I want to be able to drive a pin high (say ~+4 to +5V) with a switch. what would be the approprate way to divide the votage? does the switched (high) portion require a resistor as well? can you show me a sample of the voltage division with the switch?
- 3. How on earth does a crystal oscillator work? sometimes it's placed in series, sometimes in parallel with a capacitor. how does the oscillation get started? wouldn't the crystal stay stationary if presented with a voltage?
- 4. If a transistor controls current based on the base current, does the current remain constant over varying voltages?
Any help is appreciated