Quote:
Originally Posted by Simonpiemon
What's slightly odd I've noticed it doesn't seem to make any difference to the needle on the avo when I switch it from 1k through 600, 300 etc it is consistently reading around 20vac. When I measure the voltage across both live pins however it measures normal?
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That's a very good sign.
Remember, an analogue meter measures current. The meter coil, which moves from 0 to full-scale depending on the current through it, has a low resistance. When measuring voltage, a much higher resistance, called the multiplier, is connected in series with it; and essentially, all the voltage is being dropped across the multiplier, so Ohm's Law on the multiplier resistance converts the current reading to a voltage, and increasing the resistance increases the voltage required to move the needle to full-scale.
So if changing the series resistance does not affect the meter needle, then what you are measuring is effectively a constant-current source; and whatever leakage path exists is only capable of delivering a limited amount of energy.