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Providing components and avoiding destructive circuits How to open a local electronics laboratory for remote access Part 3.

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Presentation on theme: "Providing components and avoiding destructive circuits How to open a local electronics laboratory for remote access Part 3."— Presentation transcript:

1 Providing components and avoiding destructive circuits How to open a local electronics laboratory for remote access Part 3

2 Outline Providing physical components for remote experimenters Assuring that it is only possible to activate harmless circuits Advanced experiments Summary

3 Component handling and circuit checking in a local laboratory The instructor puts a set of components to be used in the lab session on each workbench During the session the students are permitted to activate the sources in their circuits only when the instructor have checked that the circuits are harmless

4 Component handling and circuit checking in the VISIR laboratory The lab staff installs component sets for the lab sessions of a number of courses in the switching matrix A student can only use the set belonging to the lab session s/he has logged in to Checking if a desired circuit is harmless before it is activated is made by a virtual instructor using rules written by the teacher

5 Components used in lab exercises are installed in the matix Components for the students

6 Lab preparation in three steps The lab staff installs in the matrix the components listed in the bill of materials of the lab instruction manuals for the courses to be supported The teachers creates rules for the virtual instructor for each lab experiment The teachers care for that the proper component set are displayed in the component box on the top of the virtual breadboard

7 The circuit is created in the matrix by wiring on the virtual breadboard XML, TCP/IP, port 2324 Client computer side Equipment Server side Virtual BreadboardSwitching Matrix The procedure creating the circuit in the matrix mimics how the student wires the circuit on the breadboard

8 Breadboard Possible circuit node

9 Matrix board for components ICBL A group of 6 wire holes forming a possible node Node connector 20 pin IC socket for components with more than two leads with wire holes A component with two leads Double pole relays Single pole relays

10 Part of component board lay out The nodes are denoted A – I and 0 The other conductors in the node bus are denoted X1 – X6 and COM. They are used for power supply connections and for future expansion Relay number

11 Documentation of the matrix configuration (Component List) All the components installed in the matrix are recorded in a list called Component List (component.list) The sources are recorded in the list too Component sets for several lab sessions can be online if the matrix has a number component boards The matrix driver, Circuit Builder, uses the component list to associate the nodes of an installed component to relay numbers

12 An excerpt from the Component List *This is commentPin number * Kort OP_4_10:4_11:4_13 NC B D G NC C F NC uA741 R_4_9 A B1.6k R_4_8 B C 1.6k The text in red is not a part of the list. It only shows the pin order for components with more than two leads. NC means not connected. Board number These three components are installed on board 4

13 DMM and oscilloscope connections possiblilites The DMM board has two inputs, one for voltage or resistance measurements an one for current measurements. Either of these inputs can be connected to any two of the nodes A – I or 0 for floating measurements The ground terminal of both channels of the oscilloscope are hardwired to node 0. The other terminals can be connected to any of the nodes A – I or 0

14 DMM, oscilloscope and sources connections Source board Osc. board DMM board

15 Source connections possibilities The function generator can connect to node A. The low terminal is hardwired to node 0 The dual floating power supply can connect to X2, X3. The common terminal is hardwired to COM The non floating power supply can connect to X1. The low terminal is hard wired to node 0 The number of the source board is always 24

16 The source connections are listed in the Component List Excerpt from the Component List: * Power supply * Board 24 is the source board VDC+25V_24_4:4_5F VDC+25V_24_4:4_3 D VDC-25V_24_5:4_4 G VDC+6V_24_3:4_7 A VDCCOM_24_2 0 * Function generator VFGENA_24_1A A 0 B COM C X1 D X2 E X3 F X4 G

17 Circuit created if all installed components were connected

18 Teacher preparations All components required in a certain lab session must be online It must be possible to connect them so that the circuits in the lab assignments can be wired. It should also be possible to do harmless wiring mistakes

19 Means to avoid destructive circuits It is possible to set the maximum voltage or maximum current permitted to output from the sources The impedance levels in the loops permitted to create can be controlled

20 The teacher describes the rules in Max Lists listing all connections permitted VFGENA_1 A 0max:5 VDC+25V_1 F vmax:15 imax:0.5 VDC-25V_2 G vmax:-15 imax:0.5 VDCCOM_1 0 OP_1 nc1 B D G nc5 C F nc8uA741 R_R1 A B1k R_R2 A B1.6k R_R3 A B10k R_R4 B C 1k R_R5 B C 1.6k R_R6 B C 10k R_R7 0 B 1k R_R8 0 B10k JUMPERLEAD_S1A B JUMPERLEAD_S2A D JUMPERLEAD_S3B C JUMPERLEAD_S40 D JUMPERLEAD_S50 C For example, omit the last line if the student would not be allowed to short circuit the op. amp. output.

21 A special virtual instructor rule for current measurements using the DMM The DMM in current measurement mode are low impedance and must only replace a jumper lead If you, for example, want to measure the short cicuit current of the op. amp. this jumper lead must be installed

22 Advanced usage The workbench can be used to probe a printed circuit board or other ready-made circuit with up to 10 test points It is also possible to include components from the component box and to use the power supplies The teacher preparations are the same. The fixed circuit can be displayed in the component box as an IC chip already available in the component library

23 Example of simple a fixed circuit defined as a 16 pin IC

24 Connecting the fixed circuit on the breadboard to the matrix

25 Entering the circuit into the Component List OP_2_8:2_9:2_10nc1 A nc3 nc4 G nc6 nc7 nc8 nc9 C nc11 nc12 F D B nc16 int1 R_1_2 B C1.6k R_2_2 B C 10k R_1_9 B C 1k R_2_11 B C 120k R_1_1 B C 4.02k

26 Creating a Max List VFGENA_1 A max:5 VDC+25V_1 Fvmax:15 imax:0.5 VDC-25V_2 Gvmax:-15 imax:0.5 VDCCOM_1 0 OP_2_8:2_9:2_10 nc1 A nc3 nc4 G nc6 nc7 nc8 nc9 C nc11 nc12 F D B nc16int1 R_R1 B C 1.6k R_R2 B C 10k R_R3 B C 1k R_R4 B C 120k R_R5 B C 4.02k

27 Displaying the circuit and the extra components in the Component Box

28 A new option displaying the fixed circuit will be added

29 Part three summary

30 Summary part The VISIR laboratory is an enhancement of the local laboratory The software representing almost 20 man- years of work is published and you are invited to join the VISIR group and contribute to the further development The goal is producing engineers who have a solid and documented experience of laboratory work without increased cost per student for universities

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