6 002 Demo 03 Load set up demo 03 set Salt water Lecture 3 Agarwal Fall 00 Purpose This demo uses a tray of salt water to demonstrate concepts such as linearity superposition and Thevenin equivalent circuits The salt water is modeled as a complicated network of resistors but its properties can be summarized using simple equivalent circuits Two sets of input terminals and one set of output terminals are connected to the tray and the salt water is treated as a black box Two different signals DC and a sinusoid are placed across the inputs and the resulting output is measured The output is shown to be the sum of the responses to the individual drives Steps 1 optional In describing the demo to the students modeled by a complex linear resistor network mention that regular water or distilled water has a high resistance compared with salt water Show this using the scope by showing the output waveform growing when salt is added to the water Notes the demo can behave erratically if stirred up too much Also there is an opportunity here for a joke regarding the high conductivity of Cambridge water 2 Show the inputs constant sinusoid on the scope along with the total output Turn off the sinusoidal source by removing the cable Now show the triangle source on the scope 3 Turn on the sinusoidal source and the triangle source and observe the output with little triangle waveform ridding over the sine waveform Triangle Salt Water sin Output When Prof Agarwal Fall 00 asked question about the water if they knew where we got it Some students suggested water from Charles River Description Linearity superposition Thevenin equivalences CONNECT EXT1 Blue to INPUT EXT2 Red to OUTPUT Scope look CH1 and CH4 FG1 set freq 1 Khz Amp 1 v p p Offset zero Sine Wave FG2 set freq 10 Khz Amp 1 v p p Offset zero Triangle Wave Note see the pictorial diagram next page for more detail We use direct connection because the jumper board was picking up signal without water We use the above connection instead the one on the last page They both work Cite as Anant Agarwal and Jeffrey Lang course materials for 6 002 Circuits and Electronics Spring 2007 MIT OpenCourseWare http ocw mit edu Massachusetts Institute of Technology Downloaded on DD Month YYYY Oscilloscope Setup CH V DIV 1 on OFFSET MODE FUNC 1 0 DC off 3 off on 200 mV 0 Horizontal DC 500 us Acquisition AUTO AUTO FG1 WAVE AMP SIN 2 1 FG2 Triangle HORIZONTAL off Waveform Generator Setup UNIT VERTICAL off 2 off 4 on MATH 4 Trigger Power Supply Setup OFFSET FREQ 6 25 25 0 1 Khz off off off 0 10 Khz OUTPUT Trigger INT Note 1 Note Prof Gary Removed cable completely from FG2 and did not show CH3 Add distilled water and show the output CH4 later add cambridge water and the output should be shown 2 Remove FG1 cable and connected FG2 cable and do not show CH1 later connect FG1 and show CH1 CH3 and CH4 output combination of two inputs on CH4 Prof Lang wants 2 V instead 1 V Cite as Anant Agarwal and Jeffrey Lang course materials for 6 002 Circuits and Electronics Spring 2007 MIT OpenCourseWare http ocw mit edu Massachusetts Institute of Technology Downloaded on DD Month YYYY Salt Water Red Cable input 7 13 CH3 FG2 Triangle CH4 Salt Water Output CH1 5 FG1 Sine 17 10 Blue Cable Input BNC Clips Make these connections with the Tee BNC externally because the wire has been removed from broad due to noise Cite as Anant Agarwal and Jeffrey Lang course materials for 6 002 Circuits and Electronics Spring 2007 MIT OpenCourseWare http ocw mit edu Massachusetts Institute of Technology Downloaded on DD Month YYYY Salt Water Demo 03GS set Prof Sussman Fall 01 Waveform generator setup same as prof Gray Oscilloscope setup Demo 03GS set Cable setup see below Ext Trig Ext Trig Generator 2 10 Khz Generator 1 1 Khz Output Output Sync Sync Normal water Ionized CH 1 CH 2 CH 3 CH 4 Aux Trig Oscilloscope All Grounds Tied together To set sources to zero remove BNC from output of signal generator and attach 50 ohm load terminator Put Input signals FG1 FG2 on the side facing the edge of cart and input facing the opposite side side works better with a camera looking at them Cite as Anant Agarwal and Jeffrey Lang course materials for 6 002 Circuits and Electronics Spring 2007 MIT OpenCourseWare http ocw mit edu Massachusetts Institute of Technology Downloaded on DD Month YYYY
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