Lissajous Figures (Oscilloscope X-Y): Circuit, Measurements and Online Simulator

To build this Lissajous Figures (Oscilloscope X-Y) circuit you need two function generators and an oscilloscope. Two function generators at 1 kHz and 2 kHz drive the scope's X and Y: a figure of eight. Change a frequency ratio and the figure changes. Make the 4 connections in the wiring table, press Run, and set the second generator to 1.5 kHz (FREQ knob) for a 3:2 figure, or equal frequencies for an ellipse.

Open this circuit in the free Electronics bench simulator

Parts list

Qty	Part	What it does
2	Function Generator	Sine, square, triangle or sawtooth from 1 Hz to 100 kHz, into a 50 Ω output. COM is earth. Watch it on the oscilloscope.
1	Oscilloscope	Two channels against earth (GND). Turn TIME/DIV and VOLTS/DIV to fit the wave, set the trigger level to steady it, and read Vpp, RMS and frequency. X-Y mode draws Lissajous figures. Choose a digital (DSO) or phosphor (CRO) screen.

Wiring

#	From	To
1	Function Generator (fg1) OUT	Oscilloscope CH1
2	Function Generator (fg2) OUT	Oscilloscope CH2
3	Function Generator (fg1) COM	Oscilloscope GND
4	Function Generator (fg2) COM	Oscilloscope GND

Step by step

Open the electronics bench. Open the BitForBytes Embedded Lab in your browser. A circuit with no microcontroller runs on the analog bench: no install or account is needed.
Add the parts. Add two function generators and an oscilloscope from the parts palette (Instruments, Power, Passive and Semiconductors).
Wire 1. Connect Function Generator (fg1) OUT to Oscilloscope CH1.
Wire 2. Connect Function Generator (fg2) OUT to Oscilloscope CH2.
Wire 3. Connect Function Generator (fg1) COM to Oscilloscope GND.
Wire 4. Connect Function Generator (fg2) COM to Oscilloscope GND.
Run and measure. Press Run. Set the second generator to 1.5 kHz (FREQ knob) for a 3:2 figure, or equal frequencies for an ellipse.

Lab sheet

// Electronics bench: Lissajous figures
//
// X-Y mode plots CH2 against CH1 instead of against time.
// Equal frequencies draw a line, circle or ellipse (depending on phase);
// a 1:2 ratio draws a figure of eight. The ratio of lobes gives the ratio of frequencies.

What to try

Press Run. Set the second generator to 1.5 kHz (FREQ knob) for a 3:2 figure, or equal frequencies for an ellipse.

Frequently asked questions

How do I wire the Lissajous Figures (Oscilloscope X-Y) circuit?

Make 4 connections: Function Generator (fg1) OUT to Oscilloscope CH1; Function Generator (fg2) OUT to Oscilloscope CH2; Function Generator (fg1) COM to Oscilloscope GND; Function Generator (fg2) COM to Oscilloscope GND.

What parts do I need for the Lissajous Figures (Oscilloscope X-Y)?

Two function generators and an oscilloscope.

Can I simulate the Lissajous Figures (Oscilloscope X-Y) online for free?

Yes. The BitForBytes Embedded Lab solves the circuit in time, the way SPICE does (nodal analysis with real diode, transistor and capacitor models), and gives you a bench power supply, function generator, oscilloscope and multimeter to measure it — free, in the browser.

What does this circuit show?

Two function generators at 1 kHz and 2 kHz drive the scope's X and Y: a figure of eight. Change a frequency ratio and the figure changes.