User Guide

1. Reading the display

The screen is divided into a graticule of 10 horizontal by 8 vertical divisions. You never read voltages off a scale printed on the screen; instead you count divisions and multiply by the volts-per-division and seconds-per-division settings. This is the single most important habit to build.

Markers and readouts around the graticule:

2. The signal source

On a real bench you would connect a probe to a circuit or a function generator. Here, each channel has a built-in source that plays the same role. The Signal source section of each channel panel is the circuit under test, not part of the oscilloscope — changing it is like changing what you have probed.

Waveform

Sine, square, triangle, ramp, DC or noise.

Frequency

1 Hz to 10 MHz. Drag the slider for coarse changes, or type an exact value in the box.

Amplitude

Peak amplitude in volts. A 2 V amplitude sine swings from −2 V to +2 V, so its peak-to-peak value is 4 V.

Source DC offset

Adds a steady DC voltage to the waveform. This is what makes the difference between AC and DC coupling visible.

Noise

Adds random noise, as a percentage of amplitude. Useful for seeing why the trigger needs a sensible level, and why noisy signals are harder to measure.

3. Vertical controls

One set per channel; they control how the voltage axis is drawn.

Channel on/off (switch in the panel header)

Shows or hides the channel. Turn a channel off when it is in the way — it keeps running, so the trigger can still use it.

Volts / div

The vertical scale, in a 1‑2‑5 sequence from 1 mV to 10 V per division. Smaller values magnify the trace. Aim for a waveform filling roughly 6 of the 8 divisions: large enough to read accurately, with room left to see the peaks.

Vertical position

Slides the trace up and down without changing its size, so you can separate two channels or line a feature up with a graticule line. Zero puts the channel's ground back at the centre. Moving the trace does not change any measurement.

Coupling — DC / AC

DC shows the signal as it really is, DC content included. AC blocks the DC component and shows only the variation around it. Use AC when a small ripple rides on a large DC level: a 100 mV ripple on 12 V is invisible at a scale that fits 12 V, but switch to AC and you can magnify the ripple on its own.
Remember that in AC coupling the trace no longer tells you the signal's true DC level — Vavg will read close to zero whatever the offset.

4. Horizontal controls

Time / div

The horizontal scale, 50 ns to 500 ms per division. Smaller values zoom in on a shorter stretch of time. A good starting point shows two or three complete cycles: enough to see the shape and measure a period, not so many that the trace becomes a solid band.

Horizontal position

Moves the trigger point left or right, letting you inspect what happened before or after it. The ▼ marker moves with it, and the readout shows the shift in both divisions and time. Zero re-centres the trigger.

5. Trigger controls

The trigger is what turns a smear into a readable waveform, and it is where most beginners get stuck. The scope redraws the screen many times a second. Without a trigger, each sweep starts at an arbitrary point in the waveform and the picture will not sit still. The trigger tells the scope where in the signal each sweep should start: at the moment the voltage crosses a chosen level in a chosen direction. Every sweep then starts at the same point in the cycle, and the waveform appears frozen.

Source

Which channel the scope watches for that crossing. It does not have to be a channel you are displaying.

Level

The voltage the signal must cross. It must lie between the peaks of the signal — a level above the highest peak or below the lowest can never be crossed, and the scope will never trigger. The dashed line and the T marker show where it sits.

Slope

Rising ↑ triggers on the way up through the level, Falling ↓ on the way down. Switching slope flips the waveform left-to-right about the trigger point.

Mode

Auto — sweeps regardless, so you always see something. If it cannot trigger, the trace free-runs and drifts. Best for finding an unknown signal.
Normal — sweeps only on a valid trigger. If triggering stops, the display holds the last good trace and reads WAIT. Best for a signal you have already found, and the honest way to tell whether you are really triggering.
Single — arms once, captures the first valid trigger, then stops. Use it for one-off events; press Single again to re-arm.

6. Run, Stop, Single and Autoscale

Run / Stop

Starts and halts acquisition. While stopped you can still change scales and pan through the captured record — a frozen trace is not a picture, it is data.

Single

Arms for one capture, then stops on the first valid trigger.

Autoscale

Measures the active channels and sets volts/div, vertical position, time/div and trigger level to sensible values in one press. Use it to recover when you are lost — but do the setup by hand while you are learning, because Autoscale hides exactly the reasoning you are practising.

Reset

Returns every control to its power-on state.

7. Math (combined channels)

Displays a third trace computed from the other two: CH1 + CH2 or CH1 − CH2, drawn in purple with its own volts/div and vertical position. The subtraction is the useful one in practice: it gives you the voltage difference between two points, the measurement you would otherwise need a differential probe for.

Math works on the signals themselves, not on where you have positioned the traces, so moving a channel up or down does not change the result.

8. Automatic measurements

Below the display, each active channel reports:

9. Saving screens and data

The Export panel does what the USB socket on the front of a bench scope does: it takes the captured waveform away with you, either as a picture of the screen or as the numbers behind it.

Screen image

Choose PNG or JPEG, then press Save screen image. The file contains the graticule, every visible trace, the markers and all the on-screen annotation, rendered at 1800 × 1440 pixels regardless of the size of your browser window — so a screenshot pasted into a lab report is always the same size and always sharp. PNG is the better choice for a report: it is lossless, so the thin traces and small text stay crisp. Use JPEG only if you need a smaller file.

Waveform data (CSV)

Download CSV writes the record that is currently displayed as a comma-separated table, ready for Excel, Google Sheets, MATLAB, or pandas.read_csv(). The first row is a header; there is one row per data point:

Switch a channel off and its column disappears; with both channels on you get three columns sharing one time base, which is what you want for comparing two signals or plotting one against the other.

Data points sets how many rows the file has, from 10 to 100 000. The points are spread evenly across the ten horizontal divisions on screen, so the exported record always covers exactly what you can see — change Time/div or Horizontal position and the exported window changes with it.

The voltages are the signal at the input, before Vertical position is applied — that control only moves the trace on the screen, so it does not change the exported numbers. Coupling is applied: exporting an AC-coupled channel gives you the signal with its DC component removed, just as the screen shows it. The math trace is not exported; export the two channels and combine them in your own tool.

10. Worked examples

Getting your first stable trace

1. Turn on Channel 1 and set the source to a 1 kHz sine, 2 V amplitude.
2. Set Volts/div so the waveform fills most of the screen height — at 2 V amplitude (4 V peak-to-peak), 1 V/div gives 4 divisions.
3. Set Time/div to show a few cycles. One cycle of 1 kHz lasts 1 ms, so 200 µs/div puts two cycles across the screen.
4. Set the trigger source to CH 1 and the level to 0 V — mid-way between the peaks.
5. The status should read TRIG'D and the trace should be motionless.

Measuring amplitude and frequency by hand

1. Count the vertical divisions from the lowest point of the trace to the highest, then multiply by Volts/div. That is Vpp.
2. Count the horizontal divisions for one complete cycle — easiest between two rising crossings of the centre line — and multiply by Time/div. That is the period.
3. Frequency is 1 ÷ period.
4. Check both against the measurement panel. If they disagree, you have almost certainly miscounted divisions or misread a scale.

Seeing what AC coupling does

1. Give Channel 1 a 1 V amplitude sine with a Source DC offset of 3 V.
2. In DC coupling at 1 V/div the trace sits 3 divisions high and may run off the screen. Vavg reads about 3 V.
3. Switch coupling to AC. The trace drops back around the centre line and Vavg falls to near zero — the DC has been blocked.
4. Now reduce Volts/div to magnify the 1 V sine. This is exactly how you inspect a small ripple riding on a large supply voltage.

Catching a single event

1. Set the trigger level somewhere the signal crosses only occasionally.
2. Set mode to Single.
3. The scope arms, captures the first crossing, and stops — the status changes to STOP.
4. Pan through the captured record with Horizontal position to examine what happened before and after the trigger.

11. Keyboard shortcuts

12. Troubleshooting

13. How the simulation behaves

The simulator models the signal path of a real digital scope rather than simply plotting a formula, so several real-world effects appear on their own:

• The sample rate follows the timebase (shown top right) and is capped at 1 GSa/s. At the fastest sweeps you can see the individual samples, and at slow sweeps a fast signal will alias — just as it would on the bench.
• Triggering is done on the captured samples, with the crossing point interpolated between them. That interpolation is what keeps a triggered trace steady.
• The scope always records more than one screen, which is what makes pre-trigger viewing possible.

Deliberate simplifications, so you know where the model stops:

• Channels have unlimited bandwidth and no input loading; there is no probe attenuation setting.
• AC coupling is an ideal DC block. A real input also sags the flat tops of low-frequency square waves.
• There is no measurement of rise time, duty cycle or phase, and no cursors.

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