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Understanding Electronics Basics #2

Discussion in 'General Electronics Chat' started by cowboybob, Mar 26, 2012.

  1. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    Look at this:



    Since you add exponents to multiply: 1/3+1/3+1/3 = 1 you get 10 to the 1st power.

    It should then seem obvious that if you took the exponent of 1 ad divided it by 3, you could get the cube root.

    So, if i had a number raised to a power and I wnted to find the cube root, I would just divide the exponent by 3.

    Now, it doesn't give me a number quite yet until you plug it into your calculator or use LOGS. I put LOGS ont he back burner until you learn how to deal with exponents.

    Remember the simple rules.

    The BASES must be the SAME. To multiply you add exponents. To divide, you subtract exponents. To take the nth root you divide the single exponent by n. A square root is dividing by 2 or raising to the 1/2 power.

    So what happens when you have this?:

     
    Last edited: Apr 20, 2012
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  2. Muttley600

    Muttley600 New Member

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    (10^2)^3 = (100)*(100)*(100) = 1000
    Edit: rule 1, always think before answering, 6*zero, add 6 zeros
    So answer = 1,000,000 not 1000 as that is only 10^3
    Or:
    (10^2)^3 = (10^2)*(10^2)*(10^2) = 10^6

    You don't know how much im hoping that is right, think I've stopped believing in my answers anymore.lol

    Even this looks like I've given two different answers
    Edit: I believe my answer now, * inside exponent by outside exponent
     
    Last edited: Apr 20, 2012
  3. Muttley600

    Muttley600 New Member

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    I'm getting the fraction but not the decimal yet, isn't a third .33?

    I can't believe you've got through a jar of pickles already, & I thought I was addicted to them.lol
     
  4. dave

    Dave New Member

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  5. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    Well, they are both correct, providing you could multiply.
    What is (100)*(100)*(100)?
     
  6. Muttley600

    Muttley600 New Member

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    Already noticed my numpty answer & corrected post #262, sorry, just woke up, I've been asleep all evening
     
    Last edited: Apr 20, 2012
  7. Muttley600

    Muttley600 New Member

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    Or sometimes you can make them the same:

    (2^3)(4^1)
    (2^3)(2^2)

    (2^3)(2^2) = 2^5

    Hope you can tell I'm trying, you don't wanna know how many hours it took to get that.lol
     
  8. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    #263: All I wanted to say is that an exponent can be a decimal. Yes 0.333333 is approximately 1/3.
    #266: Yep, you can do that.
     
    Last edited: Apr 20, 2012
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  9. Muttley600

    Muttley600 New Member

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    I see what that is now :) you've just taken () away
     
    Last edited: Apr 20, 2012
  10. Muttley600

    Muttley600 New Member

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    What's a nth root then, never heard of it?
     
  11. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    The n'th rooth of the number a, for instance.

    n could be 1, 2, 3, 4, 5, 6, 7, 8.....
     
  12. Muttley600

    Muttley600 New Member

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    I've got a fair way to go yet havent I, makes no sense.........yet
     
  13. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    n is just a viariable, a is just a variable.
    If n=3 and a=10; then it's the cube root of 10.
    If n=5 and a=15; then it's the 5th root of 15.
     
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  14. Muttley600

    Muttley600 New Member

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    That makes more sense, thanks :)
     
  15. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    Aren't you supposed to be sleeping? I spent an hour or so troubleshooting a broken current source that I got on ebay. Looks like it's fixable. One transistor I'll probably have to get in the UK. The cable is too expensive though. $150 USD. Range 500 fA to 100 mA. A Femtoamp is 1e-15 amps. PS: Want the pickle recipe? They are called "refrigerator pickles". Basically: sugar, apple cider vinegar, onions (cut in thin strings - 2-3 cm long), peppers (5mm x 5mm), 20 or so thin sliced cucumbers (3-4 mm) and some spices. they will keep for a year in the fridge. Another pint bit the dust.
     
    Last edited: Apr 20, 2012
  16. Muttley600

    Muttley600 New Member

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    Post # 271 was at 1:00am this morning, back up at 6am to get ready for work, been here just over an hour now
    Too much learning to do to sleep.lol
    Thanks for pickle recipe, what quantiys?
    I can't believe your getting through a jar a day.....eek!

    If you need anything from uk, I can post if you like, least I could with you helping me :)
    Strange, cause I normally find America cheaper for parts
    Happy to help you where I can
    What cable is it then?
    Yes, I understood it was a transistor you wanted from here

    But isn't it about 3:30am there??????
     
    Last edited: Apr 21, 2012
  17. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    Yea, it's like 4:00 AM and I'm not sleeping. Head hurts.

    Pickle recipe: I'll work on it. This was the best I've ever made. I made some changes to how to do the recipe. Same proportions, just done differently.

    Parts yes, obsolete parts are a problem. I ordered 5 pairs for $25 off of ebay in HK for the transistors. They went obsolete. the one I don't need is available here for about $5.00. That's cheap enough. I hope I don't get counterfeit ones. Might have to sacrifice one and rip the top off and look at the die. Complimentary pairs MJ15011/MJ15012. Other parts are easy.

    Cables: These are close: http://www.milestek.com/p-16713-pl7...llow-jacket-12-inch-triax-cable-assembly.aspx 12" IS TOO SHORT. The connector on the instrument is a 2-lug Triax which i am going to try to change to a 3 lug version after it's fixed. The 2-lug versions get mistaken for BNC connectors. They are the same size externally. There's a number of ways to go, all messy.

    Best:
    1. Change 2-lug Triax to three lug Triax or get an adapter. it's not an easy change as it looks.
    2. A Triax to 3 alligator clips (green, red, black) is very useful (3-lug preferred, 2 lug is scarce) 3' or 1 meter length preferred.
    3. A Triax adapter to BNC but with the right arrangement. center-center, inner shield to BNC shield & Triax inner shield, triax outer chield unconnected.

    They all have different advantages and disadvantages. Getting the two lug Triax to 3-lug Triax makes the most sense and then go from there.

    First, I have to get the thing fixed. I'm bidding on a 12" three-lug cable and i ordered a couple of three lug Triax female connectors which i hope will fit.

    The nice cable is sold by Keithley where they use a graphite impregnated cable so the dialectic doesn't create much friction. The friction generates a current.
     
    Last edited: Apr 21, 2012
  18. Muttley600

    Muttley600 New Member

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    Think I need new glasses, I thought that said $103 for 12" cable

    So you don't need anything from uk now?
    Can't find cable using part number, I could try using name if you like?

    But the cable looks cheap

    Is it the plugs that are expensive?
     
    Last edited: Apr 21, 2012
  19. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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  20. Muttley600

    Muttley600 New Member

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    Lol at unit question, I did wonder, but I would certainly be curious enough to ask at price difference
    Those bits aren't cheap, why is this lead so special?
     
    Last edited: Apr 21, 2012
  21. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    It starts out as a flexible wire surrounded by a dielectric (probably Teflon), then it has a 100% braided shield, Usually some graphite, and another shield with 100% coverage and then an outer jacket. I'm not sure of the frequency response.

    The connector has to maintain the integrity of the shields. There is a gold plated bit for the inner shield on both the plug and the socket.

    The outer shield is usually connected to ground. The inner shield is connected to Guard and the center conductor to HI. The idea is that the inner shield (Guard) is at the same potential as HI, there would be no leakage. You could use numbers like the difference in potential is 1 mV and the dialectic is 1 G ohm and find the error current that would flow.

    Anyway, the source looks salvageable. An overvoltage of some sort took out a cap (shorted) visibly and the fuse.That, in turn took out one output transistor. Since the other transistors are 0.08 USD to 0.20 USD each, it seems best to replace them all. The cap and the fuse have to be replaced. One of two electrolytic caps showed a much lower ESR, so they are going to both be replaced as well as one other.

    Then I'm just going to replace one for the heck of it. I have a voltage source from the same series/ERA that will cause the power supply to die if the option is plugged in. It works otherwise. The cap is the likely suspect.
     
    Last edited: Apr 21, 2012

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