Author Topic: Unknown meter movement testing. Soon to be calibration...  (Read 1551 times)

0 Members and 1 Guest are viewing this topic.

Offline Chris Wilson

  • Super Contributor
  • ***
  • Posts: 1006
  • Country: gb
  • Race car engineer, dog lover, hoarder.
Unknown meter movement testing. Soon to be calibration...
« on: November 11, 2012, 10:31:37 pm »
I bought two ostensibly the same D'Arsonval meter movements marked 0 to 500uA FSD.
Turns out they are not the same. I did the following test, which I THINK is the correct method. I connected two 1.5 volt batteries in series (as they were conveniently laying around with wires soldered to them) and a decade resistance box in series with them, and a meter. I started with a very high resistance and lowered it until I achieved FSD on one of the meters. I measured the voltage drop across the decade resistance box. I noted the resistance I had to set the box to in order to achieve FSD. Here are the figures for the two meters:

Meter 1: 2.939 volts and 6K resistance.   Meter 1 appears to be a 50uA, I think? Or have I got the decimal point wrong, and it's 500uA?

Meter 2 : 2.910 volts and 14.3k resistance.  Meter 2 appears to be a 20uA, I think? Or decimal point wrong again, and it's 200uA?

Oh dear, I should have listened to the nice man in the gown better....

 I am hopeless at maths, really HOPELESS :(

« Last Edit: November 11, 2012, 11:41:39 pm by Chris Wilson »
Best regards,

                 Chris Wilson.

Offline vk6zgo

  • Super Contributor
  • ***
  • Posts: 5224
  • Country: au
Re: Unknown meter movement testing. Soon to be calibration...
« Reply #1 on: November 12, 2012, 12:19:15 am »
Well,if your other figures are correct one is 500uA,& the other one is 200uA.

More quality control problems in the dear old PRC?

Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo