# Circuits, Theory and Simulations All circuits are simulated with either TINA TI or Multisim BLUE simulation software. I recommend downloading both of them.

### LED Voltmeter

#### Display Voltage With an LED Bar

OPAMP based comparator circuit. Equations and Simulation.
Each comparator is biased one step higher than the comparator under it. As the input voltage increases and exceeds the reference voltage on the comparator's inverting input, the output goes high and lights its respective LED

OPAMP based adder circuit. Equations and Simulation.
An adder circuit can be made by connecting more inputs to the inverting op amp. The opposite end of the resistor connected to the inverting input is held at virtual ground by the feedback; therefore, adding new inputs does not affect the response of the existing inputs.

### AA Battery Phone Charger Circuit and Simulation

#### AA Battery Phone Charger

This project demonstrates how to build a simple 3.0V to 5.0V booster circuit for 5V charging devices. Input voltage to the circuit is 2xAA batteries connected in series. The output of the circuit is 5.0V.

### 50-W Stereo (BTL) Class-D Audio Amp w/ SpeakerGuard

#### TPA3116D2 Class D Amplifier

A Class D audio amplifier is basically a switching amplifier or PWM amplifier.

### Lithium-Ion Battery Charger

#### Lithium-Ion Battery Charger

Li-ion battery charging follows a profile designed to ensure safety and long life without compromising performance.
bq24232 USB-Friendly Lithium-Ion Battery Charger And Power-Path Management IC.

### Buck Converter

#### A buck converter is the most basic SMPS topology

Assume for the moment that the "on" drop of diode D1 is zero also. Then the voltage at V1 (Fig. 1.4b)is rectangular, ranging between Vdc and ground with a "high" time of To,. The average or DC value of this voltage is Vdc Ton / T. The LoCo filter is added in series between V1 and Vo and yields a clean, ripple-free DC voltage a t Vo whose magnitude is Vdc Ton / T.

### Ambient Light Sensor

#### Ambient Light Sensor

This project demonstrates how to build a simple ambient light sensor.