DC to AC Converter

The aim of this project was to construct a DC to AC converter. The system is composed of three

main parts: a 555 timer circuit, an LC (Inductor-Capacitor) circuit, and a negative clamper with

positive biasing. The 555 timer circuit converts the DC input into a square wave with a 50% duty

cycle. The LC circuit smooths this square wave into a more sinusoidal shape, and the clamper

circuit offsets the output from the LC circuit without altering its waveform, allowing the output

signal to mimic a true AC signal centered around 0V.

To build this circuit, you will need the following components:

● 555 Timer IC

● Resistors: 1MΩ, 10kΩ (x2)

● Capacitors: 1mF (electrolytical), 390nF (electrolytical), 1uF (ceramic)

● Inductors: 4.7mH (x2)

● 5V DC power supply and 10V DC power supply

● Oscilloscope (for testing and validation)

Before physical assembly, simulate the circuit on software such as Falstad or

Multisim.

Adjust component values in the simulation to achieve the desired frequency and

waveform. Analyze the waveforms at each stage of the circuit.

●Place the 555 Timer IC on the breadboard.

● Connect pin 8 (Vin) and pin 4 (reset) to the positive rail of the power supply, and

pin 1 (Ground) to the negative rail.

● Connect pin 2 (trigger) and 6 (threshold) together.

● Attach a 1MΩ resistor between pin 2 (trigger) and the positive rail.

● Place a 390nF capacitor between pin 6 (threshold) and the negative rail.

● Connect pin 2 (trigger) and pin 3 (OUT) with a 10kΩ resistor.

● The output at pin 3 (OUT) should now generate a square wave with 50% duty

cycle. Use an oscilloscope to confirm the square wave output.

● Connect the two 4.7mH inductors in series.

● Link one end of the inductor series to the output of the 555 timer (pin 3).

● Connect the other end of the inductor series to one terminal of the 1mF capacitor.

● Attach the other terminal of the 1mF capacitor to the negative rail.

● Measure the output waveform after the LC filter to ensure it is smoothing the

square wave into an approximately sinusoidal waveform.

● Place a 1uF capacitor in series with the output of the LC filter.

● Attach a 10kΩ resistor from the junction of the capacitor and the LC filter to the

positive rail.

● Verify the output using an oscilloscope. Expect to see the waveform centered

around 0V.

● Use the circuit diagram as a reference for placing components on the

breadboard.

● Double-check all connections for accuracy.

● Power the circuit and use an oscilloscope to observe the output. Notice that the

bottom positive rail is provided with 5V DC power supply, and the top positive rail

is provided with 10V DC power supply.

● Verify that the output matches the simulation, showing an approximately

sinusoidal waveform centered around 0V.

● If discrepancies arise, re-examine the connections and component values.

● Consider potential issues like component tolerances or incorrect wiring.

● Adjust the circuit as needed based on your findings and retest.