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

A Simple Low Power Voltage Inverter

Generate AC Voltage From DC Input

The circuit is based on a Multivibrator circuit. The astable Multivibrator circuit consists of two switching transistors, a cross-coupled feedback network, and two time delay capacitors which allows oscillation between the two states with no external triggering to produce the change in state. The output of the Multivibrator connected to T3, T4 emmiter folowers.

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Treble Control Basic RC Circuit

Audio Signal Filter

Tone Control circuit shown in the figure above provides a simple way of regulating the amount of higher frequencies present in the output signal, VF1. The circuit shown above is a variable RC network between the voltage amplifier and the power amplifier stages. The value of C1 is chosen to pass the higher audio frequencies, this has the effect of progressively reducing the higher frequencies as the variable resistor slider is adjusted towards the bottom end of the tone control.

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Ultimate Headphone Driver

Amplifier For Your Headphones

This amplifier is designed to drive most headphones; Standard IEC 61938 specifies a source resistance of 120 ohms for headphone outputs but the source resistance Rs can be varied to suit a particular application.

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An OPAMP based Reststance tester

measure Resistance With Tthis Circuit

A constant-current source will establish the current through the resistance under test and measure the voltage drop that the resistance produces.

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The Wien Bridge Oscillator

Sine Wave Generator

A Wien bridge oscillator is a type of electronic oscillator that generates sine waves.

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MOSFET ON/OFF Switch

Control DC Power

A simple MOSFET circuit used to switch an external power supply ON/OFF.

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Low Battery Indicator

OPAMP Based LED Low Battery Indicator

OPAMP based low battery indicator circuit. Equations and Simulation.
The circuit monitors 9V battery status. If battery voltage drops below 7.2V (the voltage most manufacturers consider the end of battery life) the red LED turns ON.

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