25-07-2011, 06:07 PM
(25-07-2011, 02:49 PM)martyb123 Wrote: spose ill have to work out how to take the plastic face off my meter without breaking it to get the label on it i,m thinking thats not possible?? or spose they sell meters with removable faces???? youv,e really got me curious now can i not just leave it alone???
Th meter I used was from ESR Electronics - a UK company, and cost about £7.00 GBP inc Tax - about $12 AUS. Jaycar in Oz sell something similar, but it costs a lot more - $17.95 - about £11.00GBP. CAT. NO. QP5012. See here:
http://www.jaycar.com.au/productResults.asp?MID=1&SSUBID=565&SUBCATID=948&keyform=CAT2#1
http://www.jaycar.com.au/ShowLargephoto.asp?id=5337&PRODNAME=0 - 50uA MU45 Panel Meter - Moving Coil Type&IMAGE=
The clear plastic meter cover of such meters can usually be carefully prised off, then, as often as not, the scale plate is held on with two small screws. I just removed the scale plate, being careful not to damage the meter needle, turned the scale plate over, and - having printed the scale of satin photo paper, stuck it to what was the back of the scale plate, then re-assembled it.
If a meter can't be dismantled, the best thing to do is to infer the ESR from the 50uA scale, which will be in divisions of 10 from 0 to 50. 50 is of course FSD, so is zero Ohms, 40uA, is about 4 Ohms, (80% FSD), 25uA is about 10 Ohms, and 10uA is about 20 Ohms. In practice, anything with an ESR much above 4 - 5 Ohms is suspect and should be compared with a known good new one - not NOS.
Hope that helps a bit.
David
