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Sawyer-Tower Circuit

  1. Jun 30, 2009 #1
    Hey All,

    I am trying to recontruct an experiment for measuring a hysteresis loop in a Sawyer-Tower Circuit. It is a simple experiment and I attached a pdf of an undergrad lab for it.

    My question is what are the connections to the Oscilloscope. In the picture you have channel 2 and channel 1 connected to segements within the circuit, but what is the final connection to after the linear capacitor? It appears to be going to the scope, but is it a ground or something? I am refering to figure 10 in the attached experiment.

    Following the linear capacitor there is a red line connected to the scope but I am not sure what is connected to on the scope. There is also a black line across from it that is the ground to the function generator. Thanks for any help, and also excuse my misunderstanding/mistating of anything. I am not an EE.
     

    Attached Files:

  2. jcsd
  3. Jun 30, 2009 #2

    berkeman

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    I think they ran out of black banana-to-EZhook cables. That looks to be a chassis ground connection out of a banana jack on the 'scope front panel.
     
  4. Jun 30, 2009 #3

    berkeman

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  5. Jun 30, 2009 #4
    Hey thanks Beckman!!

    Ok last question. I could not find the exact same breadbox electronic circuit board. I was able to get a simple one from radioshack and I was wondering if this will work.

    I tried to duplicate the exact circuit from the earlier pdf. I attached a sketch of the circuit I made. The main gold stripe is the copper that is the power strip and it seems that all holes for this stripe are connected in series and I tried to be all elements on this strip, but also to the side, in sockets that are not in the series. Will this be ok?? Or should I have it all in series like the circuit below it (in sketch??)

    I want to duplicate the experiment as close as possible, but cant get my hands on the exact same circuits. Once again thanks for all the help
     

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  6. Jun 30, 2009 #5

    berkeman

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    If the strip down the middle is all connected, won't it short out all the components?
     
  7. Jun 30, 2009 #6
    Wow quick response.I thought that by having it on that strip would make it all in series. Should I connect it sockets that are connect by the strip?

    I am a novice when it comes to using this boards/ making this sawyer-tower circuit.
     
  8. Jun 30, 2009 #7
    I can do this but then I guess how are the connections getting to the wires and capacitors. This was confusing to me as well when looking at the pictures in the lab
     
  9. Jun 30, 2009 #8

    berkeman

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    In the picture in the document, the vertical rows of 6 holes are connected together, and isolated from all the other vertical rows. So if you put the end of one component in one hole, and the end of another component or wire in a hole either above or below it (in the same vertical group of 6 holes), that makes contact between them.

    So ou the board you bought, there should be some number of holes that are connected together, like 4-5 of them typically, in a group. Use each of these groups to help you make each junction connection.

    Can you post a picture of your board, and then another picture with the components on it in the right positions (but not soldered yet)?
     
  10. Jun 30, 2009 #9
    Berkeman, thanks for all the help.

    I attached a picture of the board I got from Radioshack.

    The ferroeletric cap. and linear capactior look exactly the same as the picture from the lab report. We made the ferroelectric cap. which is why we are testing to see if it will work. I bought several linear caps from radio shack ranging from 100pF to 100 microF. But more or less they look exactly the same as the one pictured.

    The loops for the connections I made from desheathed wires and the wires I used are 22 guage.

    Any suggestions?

    Thanks again man you are the best
     
  11. Jul 1, 2009 #10

    berkeman

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    The attachment didn't seem to work. Try again? (BTW -- we're all glad to help)
     
  12. Jul 1, 2009 #11
    Oop sorry. Here it is again
     

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  13. Jul 1, 2009 #12

    berkeman

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    It's a little hard to tell (pic is a little small), but it looks like there are groups of 3 holes connected together. Those would be the ones you would use to make your component-to-component connections. The horizontal rows of connected holes across the middle of the board are for bussing power and ground, to make those available for strapping to any of the groups of 3 holes.
     
  14. Jul 2, 2009 #13
    OK so my labmate was holding out!!

    He had the same exact board and I was able to construct the circuit just like the lab.

    So far results are mixed it works and then it doesnt.

    Berkeman, do you know of any sawyer-tower based circuits that would work for studying PZT capacitors? We want to start studying small (micron level) capacitors using an AFM tip to make contact with the ferroelectric capacitor and then connected it to the remaining sawyer tower circuit.

    We attempted it today and once again it seemed to work and other times no so much. Actually it was uncertain if it was working very well. We were getting beauitful results, but when we raised the AFM tip up the current didnt die off and the hysteresis loop remained which made us skeptical that we were correctly measuring it.
     
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