Learn 1 of analog circuits together

Since the recent project needs to contact the analog circuit so only to learn, below we start from the perspective of the project to understand the component way to start learning analog circuit

1 start with the simple starting of the motor drive.

Suppose we now have the resources on hand

Brushed DC Motor 12V 0.6W, power supply 15DC, temperature switch (there are two-way and tee Two we here are two-pass), timer switch

The function of the temperature switch is that when the temperature exceeds a certain set value, the temperature switch is disconnected, and when it is below a certain set value, the switch will be on.

Design circuit The first step in the core of our circuit is the motor so the core of our design is the motor, and the design circuit starts with the motor.

The switch in the diagram is the analog temperature switch function for when the temperature reaches 75 degrees after the switch disconnects, the motor stops working, when the temperature drops to 45 degrees switch closed, the motor starts to work.

Our project requires a 12V power supply but we dcdc the power output 15v at this point we need to reduce the 15v voltage to 12V

Now it is possible to analyze a situation if the temperature switch is connected directly to the power device.

The answer is no, for the following reasons.

Temperature sensor switch through the current is limited, so the temperature switch can not be directly connected to the power device, the temperature switch can only provide signals.

Now we're going to consider a device transistor.

When the transistor's base-level current IB>1MA transistor is in the fully conduction state of the collector and the emitter is equivalent to a short circuit, there is a 0.3V pressure drop between them. We think this 0.3v voltage is equivalent to GND

For triode Q1 When IB = 1mA then UCE = 0.3 Here we think 0.3V is the ground

Supply voltage is 12V

Learn 1 of analog circuits together