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How to open a local electronics laboratory for remote access Part 3

How to open a local electronics laboratory for remote access Part 3. Providing components and avoiding destructive circuits. Outline. Providing physical components for remote experimenters Assuring that it is only possible to activate harmless circuits Advanced experiments Summary.

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How to open a local electronics laboratory for remote access Part 3

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

  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 Virtual Breadboard Switching Matrix XML, TCP/IP, port 2324 Equipment Server side Client computer side 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 20 pin IC socket for components with more than two leads with wire holes Node connector A component with two leads A group of 6 wire holes forming a possible node Double pole relays Single pole relays ICBL 2008

  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 comment Pin number * Kort 4 1 2 3 4 5 6 7 8OP_4_10:4_11:4_13  NC B D G NC C F NC   uA741R_4_9        A B 1.6kR_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. These three components are installed on board 4 Board number

  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 DMM board Osc. board Source board

  15. 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 Source connections possibilities

  16. The source connections are listed in the Component List Excerpt from the Component List:* Power supply* Board 24 is the source boardVDC+25V_24_4:4_5 FVDC+25V_24_4:4_3    DVDC-25V_24_5:4_4    GVDC+6V_24_3:4_7        AVDCCOM_24_2        0 * Function generator VFGENA_24_1 A 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 0 max:5VDC+25V_1    F    vmax:15 imax:0.5VDC-25V_2    G    vmax:-15 imax:0.5VDCCOM_1    0OP_1    nc1 B D G nc5 C F nc8 uA741R_R1            A B 1kR_R2            A B 1.6kR_R3            A B 10kR_R4            B C 1kR_R5            B C 1.6kR_R6            B C 10kR_R7            0 B 1kR_R8            0 B 10kJUMPERLEAD_S1 A BJUMPERLEAD_S2 A DJUMPERLEAD_S3 B CJUMPERLEAD_S4 0 DJUMPERLEAD_S5 0 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_10 nc1 A nc3 nc4 G nc6 nc7 nc8 nc9 C nc11 nc12 F D B nc16 int1 R_1_2 B C 1.6k 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 F vmax:15 imax:0.5 VDC-25V_2 G vmax:-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 nc16 int1 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 1 - 3 • 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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