The topology of an electronic circuit refers to how the various components in the circuit are arranged by means of electrical connections. Understanding these basic topologies is essential for circuit design. Here are some common basic topologies and their details:

1. Series Circuit
  Definition: In a series circuit, all the components are connected into a linear path, and current flows from one component to the next.
  Features:
  Same current: The same current passes through each component.
  Voltage distribution: The total voltage is equal to the sum of the voltages on the individual components.
  Disadvantages: The failure of any one component will cause the entire circuit to be disconnected.
  Application: battery series power supply, lamp string, etc.
  Diagram: Battery, switch and load are connected in sequence.

2. Parallel Circuit
  Definition: In a parallel circuit, both ends of all components are separately connected to both ends of the power supply to form multiple independent branches.
       Features:
        voltage: The voltage at both ends of each component is the same.
       Current distribution: The current is distributed according to the impedance of the individual components, and the sum of the current is equal to the sum of the current of the individual branches.
       Disadvantages: With each additional branch, the current demand increases.
       Applications: household electrical circuit, lighting system, etc.
       Diagram: Battery and switch are connected in parallel to multiple loads.

3. Voltage Divider
  efinition: A voltage divider is a voltage divider that is connected in series by two or more resistors and distributes voltage by the ratio of resistors.
       Features:
       The output voltage can be controlled and is suitable for applications where voltage adjustment is required.
       The output voltage is proportional to the resistance.
       Applications: signal regulation, sensor signal regulation, etc.
       Schematic diagram: Two resistors are connected in series, and the output voltage is taken between the two resistors.

4. Current Divider
  Definition: A current divider distributes current through two or more resistors in parallel.
       Features:
       The current of each resistor is inversely proportional to its resistance value.
       Used to distribute the total current to the various circuit branches.
       Applications: current distribution, measurement, etc.
       Schematic diagram: Multiple resistors in parallel, the output current flows out of the branch.

5. Common Emitter Circuit
       Definition: A common transistor amplifier circuit in which the emitter of the transistor is the common end, the input signal is connected to the base, and the output signal is obtained from the collector.
       Features:
       There is a phase difference between the input signal and the output signal (180 degrees reverse phase).
       High magnification, suitable for medium and high frequency amplification.
       Applications: audio amplification, radio frequency amplification, signal processing, etc.
       Schematic diagram: The emitter of the transistor is connected to the ground, the base is connected to the input signal, and the collector is connected to the output.

6. Common Base Circuit
  Definition: The base of the transistor is the common end, the input signal is connected to the emitter, and the output signal is obtained from the collector.
       Features:
       No phase difference between input and output signals.
       Low input impedance, high output impedance, suitable for high-frequency amplification.
       Applications: high frequency amplification, current amplification, signal conversion, etc.
       Diagram: The base of the transistor is connected to the ground, the emitter is connected to the input signal, and the collector is connected to the output.

7. Common Collector Circuit
       Definition: In this circuit, the collector of the transistor serves as the common end, the input signal is connected to the base, and the output signal is obtained from the emitter.
       Features:
       The output signal is in phase with the input signal.
       High input impedance, low output impedance, suitable for current buffering.
       Applications: signal buffering, impedance matching, etc.
       Schematic diagram: The collector of the transistor is connected to the ground, the base is connected to the input signal, and the emitter is connected to the output.

8. Differential Amplifier

       Definition: A differential amplifier circuit is used to amplify the difference between two input signals, commonly used in signal processing and noise suppression applications.
       Features:
       It has a high common mode rejection ratio (CMRR), which can effectively suppress noise.
       Can increase the contrast and clarity of the signal.
       Applications: audio amplification, signal filtering, differential signal processing, etc.
       Schematic diagram: The two input signals are respectively connected to the input end of the differential amplifier, and the output is the difference.

9. Oscillator Circuit
  Definition: The oscillator circuit produces a periodic output signal through the principle of positive feedback, usually used to produce clock signals or high-frequency signals.
       Features:
       It can produce stable periodic waveform, such as sine wave, square wave and so on.
       The oscillating circuit needs to satisfy the oscillation condition (Barkhausen condition).
       Applications: clock generator, radio transmitter, signal generator, etc.
       Schematic: The feedback loop contains amplifiers and frequency selective components (such as LC circuits, transistors, etc.).

10. Filter Circuit
  Definition: A filter circuit filters out unwanted signals or noise by blocking certain frequency components.
       Features:
       According to the frequency characteristics, it is divided into low-pass, high-pass, band-pass and band-stop filters.
       Can reduce high-frequency noise or unnecessary low-frequency components.
       Applications: signal cleaning, power denoising, audio regulation, etc.
       Schematic diagram: Resistance, capacitance, inductance and other components are combined to form a filter network.

11. Hall Effect Sensor Circuit

       Definition: The Hall effect sensor is based on the Hall effect principle and is used to detect changes in the magnetic field.
       Features:
       The magnetic field changes are converted into voltage signals.
       The output signal can be used to control the system.
       Applications: Position sensor, speed detection, current sensor, etc.
       Diagram: The Hall sensor is connected to an external circuit (amplifier, etc.).

12. Operational Amplifier (Op-Amp Circuit)
  Definition: An operational amplifier is a high-gain electronic amplifier used to perform mathematical operations such as addition, subtraction, integration, differentiation, etc.
       Features:
       The input impedance is very high and the output impedance is very low.
       Various operations can be performed via external feedback elements.
       Applications: signal processing, control systems, filters, etc.
       Schematic diagram: The input of the operational amplifier is connected to an external circuit, and the output is connected to the load.