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

AC Voltage Switch using TRIAC

Switching High Voltage

Mostly TRIACs are used when you need to switch high voltage AC loads (motors, lights, solenoids, and such) ON and OFF from a microcontroller's pin. AC voltage canbe switched ON and OFF by a relay or a TRIAC.

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Audio Power Amplifier

Amplify audio signals

An audio power amplifier (or power amp) is an electronic device that amplifies or strengthens low-level electronic audio signals, such as the signal from radio receiver, pre-amplifier, and other audio sources. Signal bandwidth is between 20 - 20,000 Hz, the human range of hearing. The goal of an amplifier is to amplify input level to a level that is strong enough for driving (or powering) loudspeakers. Power amplifiers make the signal--whether it is recorded music, a live speech, or an electric guitar--audible to listeners. It is the final electronic stage in a typical audio playback chain before the signal is sent to the loudspeakers.

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Conductivity Tester Circuit and Simulation

Test Electrical Connections

This circuit will detect resistance connected to Probe1 and Probe 2 Inputs. It will sound a 3.39 kHz tone on the speaker. It will automatically turn off when the probes are not used.

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LM555 Amplifier Circuit and Simulation

Build an Amplifier Using LM555 Timer Circuit

The audio amplifier circuit diagram is shown above. Control pin 5 of LM555, is driven by T1 BC547 BJT amplifier. Pin5 of Lm555 is biased to 2/3 VCC and if you look at the LM555 internal circuit diagram you will see that this pin is an input to a differential amplifier Q4. Varying voltage at the base of Q4 modulates oscillating signal of the LM555 timer.

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Triangular and Square Wave Generator

Dual Shape Function Generator

This web page is about a triangular and square wave generator using opamp IC. Triangular wave is a periodic, non-sinusoidal waveform with a triangular shape.

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Electret Microphone Preamplifier

Amplify Microphone Input

This preamplifier can be used to increase the output of an electret microphone. This type of mic is usually buffered internally by a JFET follower so a high input impedance is not required in the preamp. This circuit is designed to operate on a single +1.8V to +5.5V power supply. The OPA364's rail-to-rail output maximizes its output voltage swing. Preamplifier gain = 1 + R1/R2; as shown, the preamp has a voltage gain of 20dB (10V/V).

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No Feedback Voltage Booster

Generates Higher Volages From Lower Input

Voltage booster is a circuit that generates higher output voltage from a lower input voltage. It works as follows. An inductor L1 is placed in series with Vdc and a switching transistor T1. The bottom end of L1 feeds the output capacitor C1, and load resistor through rectifying diode D1.

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