EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: KJDS on March 12, 2014, 10:05:33 pm
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I picked up this delightful old bridge today.
Checked it with a 7.02kohm resistor and it was spot on. It's out on low resistance values, probably the switches need a good clean.
Does anyone still use something like this, or have similar?
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I have a couple of ESI 250DA impedance bridges which are still as good as my best precision resistors.
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My first experience of a Wheatstone bridge involved a metre long resistance wire, known resistance, sensitive meter and a knife edge connector - real old school and quite accurate.
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That was probably a potentiometer :)
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I like the old stuff, had workmanship and heft.
Have an old Harrison ZM-4 B/U resistance bridge, but haven't used it much, would need to bother installing a proper battery to use it
ranges below 10 ohms to 1 Meg in 6 ranges
can do Varley loop test, Hilborn loop test, Murray loop test, use as a resistance box
(https://www.eevblog.com/forum/testgear/a-proper-way-to-measure-resistance-the-wheatstone-bridge/?action=dlattach;attach=85007;image)
have two of these Shallcross 673-D milliohmeters, including their hefty kelvin clamps and gun, would use them more but I prefer the GE
measures resistance from 0.0001 to 5 ohms in 5 ranges
(https://www.eevblog.com/forum/testgear/a-proper-way-to-measure-resistance-the-wheatstone-bridge/?action=dlattach;attach=85009;image)
the GE portable (ya right) double bridge
measures resistance from 0.0001 to 22 ohms in 8 ranges
(https://www.eevblog.com/forum/testgear/a-proper-way-to-measure-resistance-the-wheatstone-bridge/?action=dlattach;attach=85011;image)
was last calibrated in 1978, and is still spot on, it measures both my Shalltronix .0025 ohm test standards as .0025 ohms, not a hair more or less on the dial, so all 3 in accordance (multiply the reading with the range, so .050 x .05 = .0025)
(http://eev.eevblog.com/forum/testgear/de-500-lcr-meter-oem/?action=dlattach;attach=63476;image)
my LCR meter was also in accordance (the 2 test standards in series), although the GE has an extra digit
(https://www.eevblog.com/forum/testgear/de-500-lcr-meter-oem/?action=dlattach;attach=63484;image)
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I have a Kokogawa one that is quite nice, though I rarely use it, simply as a DVM is so convenient. It is nice thuogh in that it will do low resistance quite well, and can measure cable length very well.