One of the exciting new features of B2 Spice v.5 is the addition of Virtual Instruments.

Select from one of 11 instruments to power, test and analyze your circuit. Most instruments can only be used in Simulation mode (continuous Transient simulation) while a few are used to power and stimulate the circuit. Some instruments perform their owns analysis of the circuit.

All instruments are set up and viewed in the Instrument Panel that can be hidden when not in Simulation mode.

As a Digital Storage Oscilloscope, it has two input traces and an adjustable timebase, trigger source, and vertical signal scaling.

Each channel can be selected and edited by clicking on the Input Trace 1 or Input Trace 2 button in the Traces tab. Selecting a trace allows the signal node, the plot color and width and label to be set. (Plot widths over one pixel slow down the drawing of the waveform.) Additionally, the signal’s gain and vertical and horizontal offsets can be set. Also note that each trace can also be set as DC or AC input mode. This can play an important part in getting a signalto display correctly in the scope. Please see the note at the bottom on the difference between AC and DC mode.

The trigger source can be set to either channel 1 or 2 or another node in the circuit (Ext). The trigger mode can be set to AC or DC, and the triggering level can be adjusted in the Trigger Above and Below boxes. The Trigger Edge selects they how the signal is triggered. The display can be frozen by pressing the “Run” or "Single", allowing complex waveforms to seen clearly and measured. The Run buttons stops the display at the point the button is pressed. The "Single" button stops the display after one complete drawing of the scope screen. Moving the vertical and horizontal sets of calipers displays the either the vertical voltage or the percentage of the oscilloscope’s left axis and the amount of time or the equivalent frequency implied along the bottom axis. The calipers can be activated in the Vertical and Timebase tabs, for vertical and horizontal calipers respectively.

The distortion meter measures the distortion generated within a circuit, usually an amplifier.

First specify an input and an output node. An input and output node must be chosen, as the distortion meter needs an input to inject a pure signal, which will compare the output’s signal against in calculating the distortion in the output signal. Second a test frequency needs to be entered (usually 1kHz for audio circuits). You can also set the Amplitude and offset of the test signal.

The option to display the results as a percentage or in dBs is quite straight forward. One percent distortion equals the distortion’s contribution to the output signal being –40dB down in amplitude relative to the output signal.

The bar’s length expands and contracts with the distortion being measured, which makes it an analogue readout. When the measured current exceeds the distortion meter’s range, the bar changes colour from its normal blue to red. Pressing the “Auto” button overrides the fixed range and auto adjusts the range to twice the highest distortion reading it sees.

The frequency plotter measures a circuit’s frequency response and displays its measurements in a small graph.

The Input/Output tab allows you to set up the test in regards to the circuit. Under this tab, choose two nodes in a B2 A/D Spice circuit or an input part. (Behind the scenes, the Sweep instrument adds a voltage source to the circuit or if there is already a voltage source connected to the node and ground, it takes over its settings.) You should also choose two output nodes. Then select a Signal Amplitude and you are ready to run the test.

Set up the graph under the Graph Settings tab. Here you can control the graph's display of both the amplitude and the phase across the frequency sweep’s range. The Y-axis settings are the maximum and minimum limits of the graphs display, with the option to set the graph display to linear or in dB. Pressing the “Auto” button overrides the fixed Y-axis tick makings and it auto adjusts the graph’s Y-axis limits to twice the highest current reading it sees. The X-axis settings are the beginning and ending frequencies.

The last tab, Export, allows you to export the graph to various formats, including graphic files, text tables, or even copy it to the Project's graph window. You can even copy the graph into memory to paste into other applications. Pressing the “Zoom” button brings up a new window with just the graph portion of the small frequency sweep instrument.

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First choose a part in a B2 Spice circuit and then choose a pin on the part. This can be set under the General tab. The next option is the ammeter’s display range. The meter displays its measurements in two ways: text and a moving bar graph.

When the measured current exceeds the ammeter’s range, the bar changes color from its normal blue to red. Pressing the “Auto” button overrides the fixed range and auto adjusts the range to twice the highest current reading it sees.

Under the Functionality tab, choose whether the current signal is a DC or AC one. If the signal is AC, then choose whether the RMS (Root Mean Square) value, Average, Absolute Average, Peak-to-Peak, or the peak value should be used.

Behind the scenes, the ammeter instrument severs the wire connection to the selected pin and then it bridges that gap with a SPICE ammeter in the netlist sent to the SPICE engine. A virtual ammeter is automatically inserted into the virtual instruments display if an ammeter device is placed into the schematic.

Pressing the “Setup” button toggles the length of the ammeter, so that when its setup is complete, the ammeter becomes only as tall as its display band.

The function generator creates sine, triangle, and square waves to be injected into a circuit.

This instrument is functionally equivalent to the SPICE voltage source, but it adds easy frequency and amplitude changes. A node within the circuit must be specified to receive the function generator’s output signal. (the reference node is assumed to be ground.) The DC offset of the function generator’s output can be adjusted up and down.

Much like an actual bench power supply, the power supply instrument provides a selectable output voltage(s). Both regulated and unregulated power supply types are available and the actual current delivered to the circuit is displayed. Unlike an actual bench regulated power supply, the power supply instrument allows a degraded mode, wherein it functions like an unregulated power supply with ripple on its output, much like an actual raw DC power supply.

The output voltage is set in voltage-selection edit box. If voltage-regulated performance is desired, then select the Regulated button for type. On the other hand, if you wish to simulate a cheap power supply, such as a wallwart, then select Unregulated for type and set the regulation to 25%, the noise to 500mV and the current to the idle current of your circuit. The regulation percentage refers to the over voltage an unregulated power supply develops when unloaded.

The power supply noise’s frequency equals twice the wall voltage’s frequency, for example, 120 Hz, when the wall voltage is at 60 Hz. The noise’s waveform is selectable. Actual capacitor smoothed power supplies produce a triangular noise waveform; choke input power supplies, something closer to a sine wave waveform; and some switching power supplies, a square wave waveform.

The transient signal recorder is designed to record up to two signals for either a predetermined period or the entire length of the simulation run and save the data to a file.

Setting up the Transient Recorder is as simple as specifying the Trace node(s) and reference node(s) and then setting up the capture window. The Traces tab is where you set up the signal(s) to record.

The Data Capture's All setting captures and saves the data for the entire length of the simulation run until you stop the simulation. The Most Recent button activates the Duration box and allows you to specify a certain period of data to save.

If you specify the most recent 5 seconds to capture, and the simulation runs for 23 seconds, only the data from seconds 18-23 are captured. Everything else is discarded. The Fixed button activates both the Start and Duration boxes and allows you to specify that a certain time interval's data is kept. If you specify a start of 1 second and a duration of 5 seconds, then only the data from seconds 1 to 6 are kept. Note that the Duration is not the same as a stop time. It specifies the LENGTH of time, not a fixed time.

Again, the Interactive Viewing settings are independent of the Data Capture settings. The All, Most Recent, and Fixed boxes function like the Data Captures settings, but this only affects the graph display. Note that even data that is not displayed in the graph can be retained for saving to a file. If a Most Recent viewing interval of 50ms is specified and the Data Capture setting is set to All, then only the most recent 50ms of data is shown, but ALL the data is being stored in memory and can be saved to a file.

Purpose: The measurement and display of relative strength of two voltages (AC or DC) across or inside a circuit in dBs (decibels).

Signals often differ by great magnitudes. The miniscule output voltage from a moving-coil phono cartridge (.1mV) becomes amplified to 1000 volts peak-to-peak at the tube-amplifier’s output tube’s plate.

The ratio between these two voltage is 10,000,000.

But expressed in dB (decibels), this ratio becomes only 140 dB, a figure that is much more manageable.A linear display of relative signal strength can be used by pressing the “Linear” button. The display will then show the second signal divided by the first signal.

To measure the ratio between to signals in or through a circuit, the Gain Meter must be attached to two nodes and their references (usually, ground). The gain meter displays its measurements in two ways: text and a moving bar graph. The bar’s length expands and contracts with the ratios/gain being measured, which makes it an analog readout. When the measured signal gain exceeds the gain meter’s range, the bar changes color from its normal blue to red. Pressing the “Auto” button overrides the fixed range and auto adjusts the range to twice the highest distortion reading it sees.

If the signal is AC, then choose whether the RMS (Root Mean Square) value, Average, Absolute Average, Peak-to-Peak, or the peak value should be used. Then select a sample period for the ammeter.

This instrument measures the distortion of a circuit when two sinusoids of different frequencies (Fa and Fb) are applied at the input.

The Intermodulation distortion meter has three set-up modes, SMPTE (Society of Motion Picture and Television Engineers), CCIF, and manual setup. The SMPTE test uses a signal made up of two separate sin waves.

The first sin component has a high amplitude and low frequency (60Hz, Fl), and the second has a high frequency (7kHz, Fh) and low amplitude (¼ strength of the 60Hz component’s amplitude). Sidebands appear in the frequency response at 60Hz intervals around the 7KHz tone. The percent intermodulation distortion is defined as the percentage of amplitude modulation represented by the 2nd and 3rd sidebands, i.e. Fh +/- Fl, and Fh +/- 2Fl).

The CCIF test uses a source made up of two high frequency, equal amplitude components whose frequencies are separated by a small frequency (e.g. 1Kh). The program defaults to source signal components at frequencies of 13kHz and 14kHz. With this test, the percent intermodulation distortion is defined as the amplitude of the frequency component at Fh-Fl as a percentage of the source amplitude.

The single frequency distortion test and the intermodulation distortion tests are often performed on amplifier circuits because with this class of circuit you want to minimize the distortion of the signal during the amplification process.

The voltmeter measures the voltages present in a circuit at specific points.

Choose a node to for the positive and negative nodes using the drop down box or by using the "Probe" tool next to the drop down boxes. Using the probe tool and clicking on a node that you would like to measure automatically selects that node in the drop down box.

You should also be aware that voltmeter instruments are automatically inserted if you place a voltmeter part in the schematic.

The meter displays its voltage measurements in two ways: text and a moving bar graph.

Pressing the “Auto” button overrides the fixed range and auto adjusts the range to twice the highest voltage reading it sees.

Pressing the “Setup” button toggles the height of the voltmeter, so that when its setup is complete, the voltmeter becomes only as tall as its display band. Note that a voltmeter virtual instrument is automatically inserted if a voltmeter part is placed in the circuit.

The watt meter measures and displays the power dissipation by a circuit element.

Connecting the power meter to a circuit can be done in two ways in the Circuit Setup tab: by selecting an individual part or by selecting two nodes within the circuit. The Meter Options tab control the display of the meter.

The meter displays its measurements in two ways: text and a moving bar graph.