Solve Two Circuits: PPG & 2-ch Amplifier | Find KVL, KCL, LED Output

  • Engineering
  • Thread starter amirgh
  • Start date
  • Tags
In summary, the conversation is about a request for help in solving two circuits in PSPICE and on a breadboard. The values of each part of the circuits, as well as the application of KVL and KCL, are needed. The first circuit involves a photoplethysmograph (PPG) that is used to monitor a person's pulse. It consists of a LED, phototransistor or photodiode, and amplification circuitry. The second circuit is a 2-channel amplifier for an MP3 player. The necessary images for both circuits are provided.
  • #1
i need help to solve these two circuit as my professor said in university.
i must find the value of each part to make these two circuits in pspice and in breadboard.

i need the values and KVL and KCL.
the first photo is PPG and voltage for each v must be 9 volt and output must be LED.
the second one is 2 channels amplifire for mp3.

more information about first one :

The photoplethysmograph (PPG) is a device with which one may monitor an individual’s pulse by measuring the light transmittance through a finger, earlobe or toe for example. The word plethysmograph comes from the Greek plethysmos,meaning enlargement, which in this case refers to the slight enlargement of the arteries with surges in blood flow as the heart pumps. A typical PPG circuit consists of a light-emitting diode (LED), a phototransistor (PT) or photodiode that responds to received light by generating a photocurrent, and amplification circuitry to bring the signal to a more manageable levelthanks
Last edited by a moderator:
Physics news on
  • #2
Forum rules require you to have a go first. Show us your attempt and tell us where you have got stuck. That way we don't waste time explaining things you already know. There is also a homework template to use.

1. What is the purpose of solving two circuits in this experiment?

The purpose of solving two circuits, specifically the PPG and 2-ch Amplifier circuits, is to understand the principles of Kirchhoff's Voltage Law (KVL) and Kirchhoff's Current Law (KCL) in a practical setting. These laws are fundamental in analyzing and solving electrical circuits, and this experiment allows for hands-on experience in applying them.

2. How do you find KVL and KCL in the PPG and 2-ch Amplifier circuits?

KVL and KCL can be found by analyzing the circuit diagrams and using the equations associated with each law. In the PPG circuit, KVL can be found by summing the voltage drops across each component in a closed loop, whereas KCL can be found by applying the conservation of charge at each node. In the 2-ch Amplifier circuit, KVL and KCL can be found by applying the same principles.

3. What is the significance of LED output in this experiment?

The LED output in this experiment serves as a visual indicator of the voltage and current in the circuit. By analyzing the LED output, one can confirm the accuracy of the calculations and understand the behavior of the circuit. The brightness of the LED is directly proportional to the voltage and current in the circuit, providing a simple and effective way to observe changes in the circuit.

4. How can solving two circuits be applied in real-world scenarios?

Solving two circuits is a crucial skill in designing and analyzing electrical systems, making it applicable in various real-world scenarios. For example, it can be used in circuit design for electronic devices, power distribution systems, and renewable energy systems. It is also essential in troubleshooting and repairing faulty circuits in various electrical and electronic devices.

5. Are there any limitations to using KVL and KCL in circuit analysis?

While KVL and KCL are fundamental laws in circuit analysis, there are some limitations to their application. For instance, they assume ideal conditions, such as negligible resistance in wires and perfect components, which may not always be the case in real-world scenarios. Additionally, KVL and KCL may not be applicable in circuits with non-linear elements, such as diodes and transistors.