# Welcome to Electronics Area

## Dual polarity Variable voltage source

Dual polarity variable voltage source (+/- 15 volts).

Voltage source with a maximum amplitude of +/- 15 volts an a current up to 1.5 amps.

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## Current Divider Rule in parallel resistors

Current divider in parallel resistors

By using the current divider rule, we can find the current in each resistor connected in parallel. The electric current passing through a circuit of two resistors in parallel is divided in two.

## 12 to 5 volt Converter Circuit (for cars)

12 to 5 volt converter circuit (for cars)

This 12 to 5 volt converter circuit for cars is very useful. It can be used to connect 5-volt electronic devices in a car with a 12v battery. (Automotive lead-acid batteries may have a voltage of up to 13.5 volts).

## Logic OR gate

The logic Or gate is one of the simplest digital logic gates. The output of this gate is “High”, when one or all of its inputs are “High”. We can also say that, the output of an OR gate is “Low” only when all gate inputs are “Low”.

## 12 volt Power Supply using 7805 regulator

12 volt Power Supply using 7805

This 12 volt power supply circuit is simple and very useful. Sometimes a 12 Volt power source is needed, and we only have 5 or 9 volt regulators (7805, 7809)

## Flashing LEDs Circuit for Pedestrians using NAND gates

This is a simple flashing lights circuit uses high-intensity white LEDs that turn on and off continuously. It may be placed in any part of the body, such as an arm.

## Continuity tester using 741 IC

Continuity tester using 741 operational amplifier that operates as a differential amplifier.

A good application for this circuit would be to test welds made on a printed circuit board. It could also be used to test continuity of wires, connections, etc.

## Thermistor Controlled Fan Circuit – AC Fan

Thermistor controlled fan circuit

This circuit varies the speed of a fan connected to a 110 or 220 Volts outlet, using just three transistors and a few additional components.

## Measuring Low Resistances

Measuring Low or very low resistances

There are cases where the resistance is too low and a direct use of the ohmmeter is not practical. So a special method is needed

## NAND Gate – The Universal Gate

The NAND gate, also called universal gate, is a gate that produces a logic “0” output only when all logic inputs are “1”. The NAND gate truth table

## The logic NOT Gate – Symbol, Truth Table

The NOT gate is a logic gate that has only one input and one output. The output logic level is the opposite of the input logic level

## How to Measure Resistance with a multimeter

How to use a multimeter to measure resistance (resistor value). The range selector. Digital multimeter and analog multimeter / VOM

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