On 8/2/26 09:44, Tony Miklos via Jukebox-list wrote:
I've looked before but not found anything on the internet explaining ohms/volt in a meter. As I was taught is that all volt meters draw a very slight current from the voltage you are measuring, putting a very slight load on the voltage. The AC you are reading isn't direct AC from the line voltage, it is from induction, so it can "provide"? only a very low current.
Essentially, the ohms-per-volt specification is the loading of the meter across the device under test expressed as the resistance based on the full-scale reading of the meter. This is usually a factor with analog meters having a moving needle. Digital meters often have a high-impedance buffer where it is not a factor.
If the meter is set to a full-scale reading of 250 volts and it has a 1000 ohms-per-volt spec, it will present a 250K resistance across its leads. Switch it to 10 volts full-scale and it will present a resistance of 10K ohms.
Digital multimeters and old-school VTVMs typically load the input to 10 megohms or more regardless of full-scale setting.
If you're measuring AC leakage to a chassis or device you're likely to see a much higher reading with a higher impedance meter. Similarly with vacuum tube circuits which tend to be high impedance.