Free 186 More Best Homemade Tools eBook:  
Get tool plans

User Tag List

Page 23 of 101 FirstFirst 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 73 ... LastLast
Results 221 to 230 of 1007

Thread: High-quality black-and-white photographs of large old machines and tools

  1. #221
    Supporting Member mklotz's Avatar
    Join Date
    Aug 2015
    Location
    LA, CA, USA
    Posts
    3,515
    Thanks
    362
    Thanked 6,548 Times in 2,156 Posts

    mklotz's Tools
    Quote Originally Posted by Toolmaker51 View Post
    What great site! I have a decent [?] meter but I suspect not in keeping with Marv's description.

    The problem with measuring very small resistances is that the resistance of connections becomes so important relative to the resistance one is attempting to measure.

    Put your ohmmeter on its lowest scale and, with fingers off the exposed metal on the probes, press the metal tips together. Now, by adjusting the pressure with which you press the tips together, you should be able to change the indicated resistance by a large relative amount.

    Keep this in mind when you make your resistance measurements.

    186 More Best Homemade Tools eBook
    ---
    Regards, Marv

    Experience is always far worse than pessimism

  2. The Following 2 Users Say Thank You to mklotz For This Useful Post:

    Toolmaker51 (Sep 7, 2019), volodar (Sep 7, 2019)

  3. #222
    Supporting Member Toolmaker51's Avatar
    Join Date
    Feb 2016
    Location
    Midwest USA
    Posts
    5,334
    Thanks
    7,044
    Thanked 3,011 Times in 1,900 Posts

    Toolmaker51's Tools
    I did that with my fingers.
    Are resulting figures weight, blood pressure or a grip test?
    Sure doesn't appear to be IQ!

    2,000+ Tool Plans
    Sincerely,
    Toolmaker51
    ...we'll learn more by wandering than searching...

  4. #223
    Supporting Member hemmjo's Avatar
    Join Date
    Feb 2017
    Posts
    2,659
    Thanks
    251
    Thanked 1,514 Times in 855 Posts

    hemmjo's Tools
    when doing tests like this, where the connection is so important, it is good to use alligator clips. to assure a good connection. I have a short pair of red and black cords with a clip on each end. The teeth cut through any surface corrosion on the wire so you get good consistent readings.

  5. #224
    Supporting Member mklotz's Avatar
    Join Date
    Aug 2015
    Location
    LA, CA, USA
    Posts
    3,515
    Thanks
    362
    Thanked 6,548 Times in 2,156 Posts

    mklotz's Tools
    Don't forget that there is another set of connections where the meter test leads connect to the meter itself. These are generally banana plugs so wiping occurs with every insertion.

    I'm trying to remember the Wheatstone bridge we used in physics lab at college. I seem to remember screw-down connectors for attaching the unknown but it's been a long time.
    ---
    Regards, Marv

    Experience is always far worse than pessimism

  6. #225
    Supporting Member mklotz's Avatar
    Join Date
    Aug 2015
    Location
    LA, CA, USA
    Posts
    3,515
    Thanks
    362
    Thanked 6,548 Times in 2,156 Posts

    mklotz's Tools
    Rather than the error-filled minefield of resistance measurements, why not do it with weight? Weigh a small piece, weigh the coil and the math is the same as I indicated above.

    Accurate scales are available and, if all fails, you can use a balance scale with measured quantities of water as the balance weights.
    ---
    Regards, Marv

    Experience is always far worse than pessimism

  7. The Following 2 Users Say Thank You to mklotz For This Useful Post:

    jimfols (Sep 7, 2019), Toolmaker51 (Sep 7, 2019)

  8. #226
    Supporting Member jimfols's Avatar
    Join Date
    Sep 2015
    Location
    Ontario Calif USA
    Posts
    853
    Thanks
    2,150
    Thanked 547 Times in 288 Posts
    Quote Originally Posted by mklotz View Post
    Rather than the error-filled minefield of resistance measurements, why not do it with weight? Weigh a small piece, weigh the coil and the math is the same as I indicated above.

    Accurate scales are available and, if all fails, you can use a balance scale with measured quantities of water as the balance weights.
    The measured quantities of water is what made me fall in love with the metric system.
    Jim

  9. #227
    Supporting Member mklotz's Avatar
    Join Date
    Aug 2015
    Location
    LA, CA, USA
    Posts
    3,515
    Thanks
    362
    Thanked 6,548 Times in 2,156 Posts

    mklotz's Tools
    Quote Originally Posted by jimfols View Post
    The measured quantities of water is what made me fall in love with the metric system.
    Indeed, only an idiocy like the inferial system would have a unit called fluid-OUNCE (caps mine) that is a measure of volume, not weight.
    ---
    Regards, Marv

    Experience is always far worse than pessimism

  10. The Following 2 Users Say Thank You to mklotz For This Useful Post:

    Toolmaker51 (Sep 7, 2019), volodar (Sep 7, 2019)

  11. #228
    Supporting Member Ralphxyz's Avatar
    Join Date
    Dec 2016
    Posts
    1,728
    Thanks
    3,178
    Thanked 292 Times in 239 Posts

    Ralphxyz's Tools
    I have lost track of what is trying to be accomplished here?

    Ralph

  12. #229
    Supporting Member Big Sexy's Avatar
    Join Date
    Feb 2017
    Posts
    164
    Thanks
    4
    Thanked 26 Times in 23 Posts
    Which I prefer my first suggested method of counting loops and multiply by the diameter of the loops. Then you can do a ohm test to confirm a length is good to go without breaks.

  13. #230
    Supporting Member mklotz's Avatar
    Join Date
    Aug 2015
    Location
    LA, CA, USA
    Posts
    3,515
    Thanks
    362
    Thanked 6,548 Times in 2,156 Posts

    mklotz's Tools
    Quote Originally Posted by Big Sexy View Post
    Which I prefer my first suggested method of counting loops and multiply by the diameter of the loops. Then you can do a ohm test to confirm a length is good to go without breaks.
    And then multiply the result by pi because the length of a loop is the circumference, not the diameter.
    ---
    Regards, Marv

    Experience is always far worse than pessimism

Thread Information

Users Browsing this Thread

There are currently 6 users browsing this thread. (0 members and 6 guests)

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •