Table of Contents
- User Interface
- Circuit Management
- Inserting Elements
- Selecting Elements
- Moving Elements and Labels
- Editing Elements
- Undo and Redo
- Export and Screenshots
- Interactive Book
- Calc & Info
Electric Circuit Studio (ECStudio) is a set of powerful tools used for building electronic circuits, SPICE simulation, and calculation of circuits. These tools are complemented by the information center containing resources, connector pinouts and interactive physics book explaining basic electrical theorems, laws and circuits. It is a useful application for all electronics hobbyists, students, kids trying to understand electronic circuits, or other people with an interest in electronics.
Schematic editor and SPICE simulator allow easy creation of circuit diagrams and SPICE analysis of the created circuits. ECStudio simulator is focused on visual representation of simulated results, such that simulated voltages and currents can be placed elsewhere in the circuit, as a text or graph. Moreover, the magnitude and polarity of voltages and currents can be represented by visual indicators, so you can check the results quickly. All results can be additionally displayed on the top plot, where they can be explored using two cursors.
DC, AC and Transient analyses are supported. The simulation can be run repeatedly (in Transient analysis) and results can be displayed consecutively with a user controlled speed (in all analysis types), or all simulation results are displayed immediately. When the results are shown consecutively, you can control parameters of circuit elements by the seek bar and see the change of results in real time.
The application supports two modes: Normal and Restricted. The Restricted mode differs from the Normal mode in that the size of the drawing canvas is restricted to the size of the circuit, elements cannot be inserted, moved, rotated, flipped or deleted, and the undo, redo, saving and opening circuits are not allowed. This mode is intended to be used only for simulation of circuits.
The application uses the shared storage to store circuits, pictures, models, screenshots, exported and log files. This storage is usually internal memory, or it can be an external SD card. The location of the application directory is Documents/ECStudio (or Documents/ElectricCircuitStudio for the free version of the application).
Basic user interface of the application consists of the Action bar, Toolbar, Element bar, Plot window, Menu, and Drawing canvas. The Menu can be opened by taping the Overflow icon:
|Bring to Front|
|Send to Back|
Modifying User Interface
To modify the user interface, you can use the following commands.
To scale the Drawing canvas to fit the whole circuit, tap the Reset View button from the Toolbar.
The Drawing canvas can be reduced or enlarged with a double-tap (if applicable) or a two-finger spread gesture.
If the Restricted Mode item from the Menu is checked, the view will be scaled to fit the whole circuit and the application will be switched to the Restricted mode.
If the Show Plot item from the Menu is checked, the Plot window will be displayed after the start of simulation. This window can be hid immediately by a fling down gesture.
Show Bottom Bar
If the Show Botttom Bar item from the Menu is checked, the Element bar will be shown on the bottom.
Circuits used in ECStudio are located in the directory <app directory>/Circuits.
Creating new Circuits
Choose New Circuit from the Menu. This opens an empty document in the Normal mode.
Use Save from the Menu to save the current circuit.
Use Save As from the Menu to save the current circuit with a different file name.
Use Open Circuit from the Menu to show Open Circuit dialog, allowing you to find a desired file and tap on its name. Or you can use Favorites to open a bookmark file. In the Open Circuit dialog you can delete, rename or bookmark (add to favorites) a file using the long tap gesture. There is also a search form to quickly search for a file.
Properties of Circuits
Choose Properties from the Menu to show Properties dialog, allowing you to change various settings of the current circuit.
Enter a single-line title text.
Enter a description text. This text is visible in Open Circuit dialog.
Start time for the Transient analysis.
Stop time for the Transient analysis.
The number of points for the Transient analysis. It can be from 20 to 5000.
Use initial conditions
If checked, the simulator uses the initial values of appropriate elements entered using an extra parameter (IC=...) as the initial conditions in the Transient analysis.
If checked and the circuit contains Vsin and/or Vpulse sources, the start and stop times are calculated automatically from the periods of these sources.
Start voltage for the DC analysis.
Stop voltage for the DC analysis.
Step voltage for the DC analysis.
Select a name of the independent voltage source to be swept.
Start frequency for the AC analysis.
Stop frequency for the AC analysis.
The number of points for the AC analysis. It can be from 1 to 10000.
Select a type of the x-axis. The LIN type makes the x-axis to be divided linearly. The DEC and OCT makes the x-axis to be divided logarithmically (by decades or octaves).
Select a type of the analysis for the simulation. The most common analysis is the Transient analysis, which calculates (instantaneous) voltages and currents of the circuit as a function of time.
In the AC analysis, the frequency of sinusoidal voltage sources (Vsin) is swept over a user-specified range. The magnitude, real value, imaginary value and phase of (small-signal) voltages and currents are then calculated as a function of frequency. It follows that at least one sinusoidal voltage source is required for a meaningful AC analysis. Further, only Amplitude and Phase parameters of this source are used in the AC analysis.
In the DC analysis, a chosen DC voltage source is swept from the Start voltage to the Stop voltage in increments of the Step voltage. DC voltages and currents of the circuit are then calculated for each value of the sweep. It follows that at least one DC voltage source is required in the DC analysis.
In the DC and Transient analysis, only Real (instantaneous) number types can be used.
Adds gridlines to the X and Y axes of the circuit.
Displays Select color dialog to set the color of gridlines.
Show pin numbers
Shows pin numbers of selected elements.
Canvas text color
Displays Select color dialog to set the color of pin numbers and label texts of newly created elements.
Canvas background color
Displays Select color dialog to set the color of Drawing Canvas.
Plot foreground color
Sets the color of Plot window.
Plot background color
Sets the color of texts and lines of the Plot window.
Box border color
Sets the color of label border.
Displays Select color dialog to set the color of various control elements (scrollbars, cursor lines, etc.).
Symbol line width
Sets the width of element's lines. It can be between 0.2 and 20.
Symbol line color
Sets the color of element's lines and circuit junctions.
Graph line width
Sets the width of graph lines. It can be between 1 and 10.
Sets the minimum relative size of current and voltage indicators. It can be between 0 and 1.
Sets the maximum absolute size of current (width) and voltage (radius) indicators in pixels. It can be between 1 and 100.
Sets margins of all labels except Output labels.
Sets margins of all Output labels.
Displays IEC-style symbols.
Controls the precision of numerical results in the Output labels as well as in the Plot window. It can be from 2 to 10. The precison of results in the Plot window will be Precision + 1.
Resets properties of the current circuit to the default values, except for Title and Description.
Each element can have attached several labels:
These labels are used to display simulation results, parameters of elements, or some text. When you move an element, its labels also move, but labels can be moved or rotated independently of elements. By rotating or flipping an element you can reset the position and rotation of the element's labels.
If a file with the name library is copied to the ECStudio directory, the file will be used instead of the internal file to load element definitions. This can be used for eventual change of properties of elements and labels, but only by experienced users!
Labels can be of four types: Parameter labels, Text labels, Output labels, and Designation labels. Parameter labels are used to control the main parameter of elements. Text labels can be used only for showing a text. Output labels allow to display plots, indicators, graphs and numerical values of corresponding variables (voltages or currents). And finally, designation labels are used to mark elements.
An Output label is always attached to a variable of the circuit. This variable can be a voltage, voltage drop or current. In the case of the voltage or current, the Output label belongs to one pin of the element and one node of the circuit. As the voltage drop is always determined between two points of the circuit, the Output label attached to a voltage drop belongs to two pins of the element and two nodes of the circuit.
The numerical value and graph of a variable attached to the Output label are displayed inside the label. The graph of a variable can be shown also in the Plot window, while a graphical representation (indicator) of the numerical value can be drawn in the element. The type of the variable, pin and node numbers pertaining to the Output label are shown in the top line of the Label Properties Dialog. Before simulation, Output labels contain a text, which show a type of the variable (volt. for voltage or voltage drop and curr. for current) and the pin numbers, for which the labels will display the variable values or graphs.
In the case of the voltage drop variable, the label belonging to this variable will display the voltage drop (difference) between two pins of the element. The numerical value displayed in the label is an absolute value, as the direction (sign) of the voltage is shown by an appropriate indicator:
In the case of the voltage variable, the label belonging to this variable will display the voltage between the pin of the element and the ground:
And in the case of the current variable, the label will display the current flowing to the pin of the element. The numerical value displayed in the label is an absolute value, as the current direction (sign) is shown by an appropriate indicator:
Indicators are used for visual representation of simulated results. They are of three types: current indicators, voltage indicators, and voltage drop indicators.
Current indicators are drawn as colored arrows inside elements, which show the direction of the current throught elements (in the Transient and DC analyses) or the sign of current (in the AC analysis). The width of arrows represents a relative magnitude of the current.
Voltage indicators are drawn as colored circles around the appropriate pin. The radius of a circle represents a relative magnitude of the voltage.
Voltage drop indicators are drawn as colored line arrows between appropriate pins. The length of an arrow represents a relative magnitude of the voltage drop. The line arrow also shows the direction of the voltage drop in the Transient and DC analyses, or the sign of drop in the AC analysis (see the example below).
The picture above shows imaginary values of voltages across three elements in a simple circuit. As the voltage across the capacitor C3 points from pin 2 to pin 1 (blue arrow), which is the opposite direction comparing to its default direction, the value of this voltage is considered as negative. This corresponds to the negative value displayed on the top Plot window.
The phase type of a variable (no matter it is current or voltage) in the AC analysis is considered as a separated type of the variable for the purpose of calculation of relative magnitude. The relative magnitude of a variable is the ratio of the absolute value of the variable to the maximum absolute value of all active variables of the same type (current, voltage or phase). This maximum value is calculated through the whole simulation interval.
An Output label is active, if it has at least one of these options checked in the Label Properties Dialog: Show text, Show graph, Show indicator, Show plot. The variable belonging to the active label is also considered as active.
The Element bar on the bottom of screen allows inserting these elements:
|DC voltage source|
|Pulse voltage source (Vpulse)|
|Sinusoidal voltage source (Vsin)|
|DC current source|
|NOT logic gate|
|AND logic gate|
|NAND logic gate|
|OR logic gate|
|NOR logic gate|
|XOR logic gate|
|XNOR logic gate|
|Voltage controlled voltage source (VCVS)|
|Voltage controlled current source (VCCS)|
|Current controlled voltage source (CCVS)|
|Current controlled current source (CCCS)|
Elements are inserted into the grid with a cell size of 100x100 pixels. The picture element allows inserting a bitmap picture, which should be placed in the <app directory>/Pictures directory. The name of this bitmap can be inserted through the File parameter of the element. The center of the bitmap is always positioned at a intersection of gridlines.
Models of transistors and diodes can be inserted as files into the directory <app directory>/Models. To assign a model to an element, enter the name of the model file to the Model parameter of the element. The values of numerical parameters entered through the Element Properties Menu will then be ignored.
By a long tap on an element button you can display the name of the element.
To draw a wire, tap the Wire button in the Element bar and then tap the start end end points of the wire to be drawn. If these points do not lie on a vertical or horizontal line, the wire will be drawn using autorouting, otherwise a simple one-line wire will be created.
To select only one element, tap some place on the element outside of the element's labels. All labels attached to the element are then displayed, and a green rectangle will be drawn around the element.
To select multiple elements, tap the Select button in the Toolbar and then tap the top left-hand as well as bottom right-hand corners of the area containing the elements to be selected.
To deselect only one element, tap some place on the element outside of the element's labels.
To deselect multiple elements, tap the Select button in the Toolbar and then double tap some place outside the circuit elements.
Select All Elements
To select all circuit elements, tap the Select All button in the Toolbar.
To select a label, tap the element to which the label is attached and then tap the label. A red rectangle will be drawn around the label.
Moving Elements and Labels
To move selected elements, tap and drag them to a new position. Elements are snapped to the grid.
To move the selected label, long tap and drag it to a new position. Labels can be moved to any place of the Drawing canvas.
The multipurpose Properties button in the Toolbar allows users to set properties of elements, labels or simulation. If there is no selected element, it shows the seek bar used to control the speed of displaying of simulation results in the Continuous mode of simulation. If a label is selected, it displays the Label Properties Dialog alowing to set properties of the label. If only one element is selected and none of its labels are marked, it displays the Element Properties Menu allowing to set parameters of the element.
Element Properties Menu
The first line of the menu is always the name of the element. Next lines represent the properties of the element. By taping on some of these lines (if there is any) you can display a parameter window with a seek bar and two spinners allowing to set the chosen parameter:
The seek bar has increment of 1 and is used especially for quick changes of parameters. The left-hand spinner can be used to change the sign of the parameter, while the right-hand spinner is used for selecting a unit of the parameter. By taping the name of the parameter you can set the parameter's value through a text dialog.
For textual parameters (e.g. Model filenames), the seek bar and spinners are purposefully hidden.
Label Properties Dialog
Displays the text/value in the label.
Displays the box in the label.
Displays the graph in the label instead of the box and text. This option is shown only in the case of an Output Label.
Draws the indicator in the element. This option is shown only in the case of an Output Label.
Draws the graph in the plot window. This option is shown only in the case of an Output Label.
If checked, after finishing a Common mode simulation the seek bar of the first cursor will be opened below the plot window. The cursor can be used to obtain x and y values of the corresponding graph. This option is shown only in the case of an Output Label.
If checked, after finishing a Common mode simulation the seek bar of the second cursor will be opened below the plot window. The cursor can be used to obtain x and y values of the corresponding graph. This option is shown only in the case of an Output Label.
Select the type of corresponding current or voltage variable. In the AC analysis, you can display the magnitude, real value, imaginary value and phase of voltages and currents. In the DC and Transient analysis, only real (instantaneous) values can be displayed. This option is shown only in the case of an Output Label.
Enter a scale of the label.
Select a rotation of the label.
Select an alignment of the text inside the label.
Enter a designation of the element. This item will be shown only in the case of a Designation label.
Enter a value of the label. This item will be shown only in the case of a Parameter label.
Enter a text of the label. This item will be shown only for text elements.
Choose a color of the label's box.
Choose a color of the label's text. In the case of an Output label, this item is not shown as the foreground color is chosen automatically. The same color will be used in the graph as well as Plot window.
If checked, the label's box will be drawn rounded.
Select a font type of the label's text.
The next commands from the Toolbar can be applied to one or more selected elements.
Copies the selected elements to the clipboard and removes them from the current circuit.
Copies the selected elements to the clipboard.
Inserts the contents of the clipboard at the location of the cut elements.
Removes the selected elements from the current circuit.
Select the elements you want to bring to front, and then tap the Bring to Front button.
Select the elements you want to send to back, and then tap the Send to Back button.
You can rotate all elements along with the labels, except for wires. Select the elements you want to rotate, and then tap the Rotate Clockwise button. Labels are also rotated, according to the definition in the internal library file.
You can flip all elements along with the labels, except for wires. Select the elements you want to flip, and then tap the Flip Horizontally button. Labels are also flipped, according to the definition in the internal library file.
The next commands from the Menu can be applied only to all circuit elements.
Shows the designations of the current circuit elements.
Hides the designations of the current circuit elements.
Shows the values of the current circuit elements.
Hides the values of the current circuit elements.
Undo and Redo
Reverses the last editing command or the last change of a property.
Reverses the action of the last Undo command.
Tap Run/Stop button in the Toolbar. This opens the menu of two items. The item Run starts the Continuous mode of simulation of a type chosen in the Properties dialog, when the results are displayed consecutively with a user controlled speed. In the case of DC and AC analyses, the simulation will stop after displaying of the last result. In the case of Transient analysis, the simulation is run repeatedly with a gradually increasing Start time of the simulation.
The item Run and Show All starts the Common mode of simulation of a type chosen in the Properties dialog. After finishing the simulation all results are displayed immediatelly.
When a simulation is running, it can be stopped by taping on the Run/Stop button. In the Continuous mode, the displaying of results is then paused and these results can be thereafter explored. The next tap of the Run or Run and Show All item starts a new simulation.
At least one Gnd element is required to achieve a successful simulation.
Export and Screenshots
Use Export item from the Menu to open Export dialog.
Max. scaling factor
Down-size the image to a lower resolution. The size of target images depends on the available memory.
Enter the quality level for JPEG compression.
Enter a file name for the image.
Exports the circuit and places it to the ECStudio directory.
Taping the Screenshot button takes a screenshot without applying any theme of the device and places it to the ECStudio directory.
Taping the Book item from the Menu displays the interactive physics book in the Restricted mode. The book contains these chapters:
1. Electric circuit
3. Node voltage
4. Voltage drop
5. Electric current
6. DC current
7. AC current
8. Kirchhoff's current law
9. Kirchhoff's voltage law
10. Voltage source
11. Sine and pulse generators
12. Current source
14. Ohm's law
15. Resistors in series
16. Resistors in parallel
17. Voltage divider
18. Current divider
Calc & Info
Taping the Calc & Info button in the Action bar displays the calculator and information center.
The tool contains calculations of all basic circuits, laws as well as various converters. Some electrical circuits can be opened after the calculation by the simulator (with default element's parameters) to check and explore the results. The calculators are supplemented by formulas. These calculators are available:
Resistors in series/parallel
Resistor for voltage attenuation
Resistor for LED
LM317 voltage regulator
A/D and D/A converters
Resistor color code
SMD resistor code
Inductor color code
Battery capacity conversion
PCB trace width calculator
The pinouts of these connectors/devices are available:
ATX power connectors
RJ11, RJ14, RJ25
ISO10487 for car audio
These topics are included:
Wire insulation colors
Units of measurement
7400 series of integrated circuits