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Old 12th Jan 2020, 2:58 pm   #1563
eddie_ce
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Join Date: Aug 2010
Location: nr. Hannover, Germany
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Default Re: The "Sussex" Homebrew Valve Tester.

Just a quick note in case this is of use to prospective Sussex builders. A couple of years ago, when I first considered building Mike Rowe's excellent design I sourced the meters from Asia. These are blue LED (not LCD) types with an explicitly stated isolated power requirement of 5V DC, so not universal AC/DC as some other meters.

Now I have started building the Sussex I decided to test the meters, all seems fine although the linearity of the 200mV AC meter leaves a lot to be desired.

However, and this is what may be of significance for budding constructors, being LED types they draw between 40 and 80mA each depending on the number of segments lit. This seemed rather high to me so I checked the other meters with the same results. I wasn't sure whether the 4 6V meter windings on Ed's transformer could cope with this current demand, so I contacted him and was informed that the meter windings and lead out wires are the same, so the current carrying capabilities should be no problem although the windings were not specified for this level of current. The extra demand on the primary winding should not be a problem as we are talking about a couple of Watts and the demand on other windings will be intermittent. (Ed, please correct me if I have got this wrong).

If you are using the now more common LCD meters, I would imagine that you will not have this problem.
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