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Question Unilab Easy Read 523.001 meter

8 months 5 days ago #41229 by Techie_Paul
Does any one still use these, and if so do you have the (brown) shunts to read milliamps? Inside the shunt is a resistor in parallel across the two outer pins. Is this Brown/black/black/ silver (1 Ohm) or brown/black/black/gold (10 Ohms)?


Previous users have fried these so heavily that all is left is a burnt mass that is not totally readable, and, of course, it's decided that they are needed for a practical! Thank God for decent multimeters this time around.

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8 months 5 days ago - 8 months 5 days ago #41230 by Baldilocks
Is this really a 4 band resistor? If so then both are 1 ohm since band 3 is the multiplier (100 = 1) and the silver /gold are tolerance.

I believe that these meters were 50mV (Don't trust me - check first!) but if so then a 1 ohm shunt will give them a 50mA range.

Ian

“Do not believe everything you read on the Internet.” -Abraham Lincoln

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8 months 4 days ago #41231 by Techie_Paul
Apologies. I should have said they were 5 band resistors and I only gave you the first 4 bands. The tolerance on an existing repair was 1%, tolerance on (fried) originals unknown.

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8 months 4 days ago #41232 by Baldilocks
Even so, I think that 10 ohm is unlikely. From ohm's law 50mV across 10 ohm would give a range of 5mA. Is that what you are expecting?

“Do not believe everything you read on the Internet.” -Abraham Lincoln

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8 months 4 days ago #41233 by Baldilocks
You might be wise to put a resetable fuse in your circuit, after the panel socket but before the Y fork to the meter and shunt. You would either need a bit of Ohm's law maths or a drop in accuracy but it could save fried shunts and/or expensive meters in the future.
Around 50p each from Rabid, see:
static.rapidonline.com/pdf/64686_v1.pdf

Ian

“Do not believe everything you read on the Internet.” -Abraham Lincoln

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8 months 4 days ago #41234 by D.B.Ferguson
For info...
I made a wiki article that contains a bit on shunts and multipliers.
Even if all your resisters are unidentifiable you could make/ buy suitable resistors. (Make from e.g. constantan wire).
www.techknow.org.uk/wiki/index.php?title=Adapting_Meters

Technicians: providing solutions and more.

David Ferguson B.Sc.

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7 months 3 weeks ago #41239 by bsimmo
No help, but just for interest.
SSSERC March 1982

Unilab had another winner with their lcd. ‘Easy
Read’ meters. Requiring only one external attachment
to give each range of up to 2OVDC or 1 OADC the meters
are clearly very versatile. A resistance module and
Attachments for other ranges, including AC, will be
available. Easy Read’ meter, Cat. No. 523.001. £24.90,
20V DC attachment 523.002, £3.34, 1OA DC attacnment
523.003, £3.34.

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