6.002 Demo# 03 ( Load set up demo#03.set ) Salt water Agarwal Fall 00 Lecture 3 Oscilloscope Setup CH V/DIV OFFSET MODE FUNC MATH VERTICAL HORIZONTAL Horizontal: 500 us Acquisition: AUTO AUTO 4 Trigger: Waveform Generator Setup Power Supply Setup UNIT WAVE AMP OFFSET FREQ +6 +25 -25 OUTPUT FG1 SIN 2 * 0 1 Khz off off off6.002 Demo# 03 ( Load set up demo#03.set ) Salt water Agarwal Fall 00 Lecture 3 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 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!!!!!! Salt Water 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 OFFSET MODE FUNC MATH VERTICAL HORIZONTAL 1 on 1 0 DC off 2 off off 3 off on 4 on 200 mV 0 DC off Horizontal: 500 us Acquisition: AUTO AUTO 4 Trigger: Waveform Generator Setup Power Supply Setup UNIT WAVE AMP OFFSET FREQ +6 +25 -25 OUTPUT FG1 SIN 2 * 0 1 Khz off off off FG2 Triangle 1 0 10 Khz 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].Red Cable inputBlue Cable Input1310177CH35CH1 Salt WaterBNC Clips** Make these connections with the Tee BNC externally because the wirehas been removed from broad due to noiseSalt WaterCH4OutputFG1 SineFG2 Triangle* 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.setProf SussmanFall 01Waveform generator setup: same as prof GrayOscilloscope setup: Demo#03GS.setCable setup: see belowExt Trig Ext TrigGenerator #11 KhzGenerator #210 KhzOutputSyncOutputSyncCH 1 CH 2CH 3CH 4AuxTrigOscilloscope Normal water(Ionized)All Grounds Tied togetherTo 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 theopposite 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
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