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Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders. |
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13th Oct 2010, 8:28 pm | #1 |
Pentode
Join Date: Aug 2009
Location: Sheffield, South Yorkshire, UK.
Posts: 167
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LCR Bridges and other Variants
Hi after reading another thread,a fellow member of the forum has aquired a LCR Bridge,without wanting to sound thick.
Can someone please explain,as to what purpose do they serve.What are they used for? Are they just like a antique version of a DMM in that you can check resistance,capatiance.inductance and other flavours, I'm really interested and curious. Please put me out of my misery and enlighten me lol. Best regards. Roger. |
13th Oct 2010, 9:18 pm | #2 |
Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,172
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Re: LCR Bridges and other Variants
Hi Roger, basically that is it; an old fashioned version of your fancy all purpose DVM.
HOWEVER! they will show much more as they usually have a loss balance or similar control that gives you an idea of the equivalent series or parallel "loss" resistance of the component. Once you get used to them they are much more accurate than DVM's. Have a read up on bridges, they all use the same basic circuit but there are a huge number of varirties. Failing that see me at Lowton and I'll give you a teach in on them. Best regards, Ed |
13th Oct 2010, 9:41 pm | #3 | |
Pentode
Join Date: Aug 2009
Location: Sheffield, South Yorkshire, UK.
Posts: 167
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Re: LCR Bridges and other Variants
Quote:
When and where exactly is the Lowton meeting? regards Roger. |
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14th Oct 2010, 9:18 pm | #4 |
Dekatron
Join Date: Jan 2004
Location: Newcastle upon Tyne, Tyne & Wear, UK.
Posts: 8,172
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Re: LCR Bridges and other Variants
Hi Roger, its on Sun 21 Nov near Lowton on the east lancs road. See meetings section for more details.
If you are lucky you may even find one there! Ed |
14th Oct 2010, 10:18 pm | #5 |
Pentode
Join Date: Aug 2009
Location: Sheffield, South Yorkshire, UK.
Posts: 167
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Re: LCR Bridges and other Variants
Hi Ed,thanks for the reply,according to the listing its members only,if that is the case.Unfortunately I am prevented from attending.
Best regards Roger... |
14th Oct 2010, 11:12 pm | #6 |
Dekatron
Join Date: Apr 2005
Location: Bewdley, Worcestershire, UK.
Posts: 4,736
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Re: LCR Bridges and other Variants
You could always join, old chap...!
The important things to realise about LCR bridges are, unlike a DMM, (a) LCR bridges don't measure voltage or current, and (b) they must be used to measure components out-of-circuit, as they apply AC waveforms to the component under test, and readings would be altered by the presence of other components. The 'loss balance' function is a very effective way of estimating a capacitor's leakage, by the way. I always use my LCR bridge to check capacitors prior to using them in a repair.
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Phil Optimist [n]: One who is not in possession of the full facts Last edited by Phil G4SPZ; 14th Oct 2010 at 11:19 pm. Reason: Info added |
15th Oct 2010, 9:21 am | #7 |
Retired Dormant Member
Join Date: Apr 2008
Location: Warrington, Cheshire, UK.
Posts: 421
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Re: LCR Bridges and other Variants
Ed et al
Just so you know the 21st November event has a new venue from the Lowton one. I shall be posting a new thread in a week or so cheers Mark PS I shall have the teach in also please! |
15th Oct 2010, 1:14 pm | #8 | |
Dekatron
Join Date: Oct 2003
Location: Croydon, Surrey, UK.
Posts: 7,549
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Re: LCR Bridges and other Variants
Quote:
SB
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15th Oct 2010, 2:11 pm | #9 | |
Dekatron
Join Date: Aug 2003
Location: near Reading (and sometimes Torquay)
Posts: 3,086
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Re: LCR Bridges and other Variants
Quote:
It cleverly balances out everything more complex than a simple component that's in parallel with the one you are measuring - and copes better with the remaining parallel combination. Seriously clever! |
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15th Oct 2010, 2:51 pm | #10 |
Retired Dormant Member
Join Date: Mar 2007
Location: Skelleftea, Sweden
Posts: 250
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Re: LCR Bridges and other Variants
here we have a nice little discussion on capacitance bridges.
http://theradioboard.com/rb/viewtopi...citance+bridge http://theradioboard.com/rb/viewtopi...bridge&start=0 |
15th Oct 2010, 4:21 pm | #11 |
Octode
Join Date: Oct 2007
Location: Exeter, Devon, UK.
Posts: 1,553
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Re: LCR Bridges and other Variants
Following up on GMB's remarks about transformer bridges. They will indeed normally test insitu components. The usual one is the Wayne Kerr B221, which also appears as MoD CT530. A lovely instrument. Covers a much wider range of circuit values than any other I know of.
I had one once, but found it difficult to use to just check a component when servicing. Not using it every day, I had to look up the manual every time. And measuring results expressed as Conductance needed thought as it is much less familiar. It was large, so I eventually sold it, and now use a TF2700, which is small. It only takes a moment usually to free one end of the component, which should go to the DET+ve terminal. Incidentally I have the test leads for the B221 somewhere, with the small connectors which plug into the panel, if any one would like them for the cost of postage. Also the LowOhm adaptor. Bill. |
15th Oct 2010, 5:06 pm | #12 |
Heptode
Join Date: Mar 2009
Location: Portsmouth, Hampshire, UK.
Posts: 674
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Re: LCR Bridges and other Variants
Bill, if that's the Q221 I'd be very interested.
PM coming soon Jim |
15th Oct 2010, 5:52 pm | #13 |
Dekatron
Join Date: Oct 2003
Location: Croydon, Surrey, UK.
Posts: 7,549
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Re: LCR Bridges and other Variants
There must be loads of these about. I know of another which is locked in a cupboard where I used to work. I doubt it will ever be used again and only hope that one of the other engineers will grab it before it's skipped.
SB
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15th Oct 2010, 7:22 pm | #14 | |
Dekatron
Join Date: Apr 2005
Location: Bewdley, Worcestershire, UK.
Posts: 4,736
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Re: LCR Bridges and other Variants
Quote:
I have heard of in-situ testers, but "seriously clever" usually means "seriously expensive and unlikely to be affordable by me!" and I confess to never having come across such an instrument. However, the OP asked a general point about an LCR bridge versus a DMM, which I think has been effectively answered now. Says he, trying hard not to sound like a Moderator...
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15th Oct 2010, 8:31 pm | #15 |
Nonode
Join Date: Mar 2008
Location: Aberdeen, UK.
Posts: 2,838
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Re: LCR Bridges and other Variants
Like Bill, I now use a TF2700, a Cropico Resistance Bridge, or a wee jappo RS lcr meter. That makes my WK B221 + all it's add-ons redundant. Wish I lived back near Mark along the East Lancs Road - would've off-loaded to someone keen(with structurally heavy shelving), buck-sheesh.
Regards, David |
15th Oct 2010, 9:55 pm | #16 |
Retired Dormant Member
Join Date: Apr 2008
Location: Warrington, Cheshire, UK.
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Re: LCR Bridges and other Variants
David
I have shelving! cheers mark |