looking for info on the weston model 301 meters as i have just gotten a half completed power supply using these meters and dont wish to damage them

Hi Kendder

You will need to know meter sensitivity to determine series resistance to measure voltage. Sometimes it's marked on the meter dial faceplate. A meter with 1 ma full scale requires 1000 ohms to read 1 volt full scale. If you want a 1 ma meter to read 100 volts the series resistor will need to be 100,000 ohms.

If your meter is 100 micro amp multiply resistance values by 10..

If you are planning on having a current meter internal meter resistance needs to be known. In this case it may be best to shunt the meter with a very low value resistor. Try 1 ohm and see what current your meter reads.

Norm

: looking for info on the weston model 301 meters as i have just gotten a half completed power supply using these meters and dont wish to damage them

Hi Kendder, Place a silicon diode each way across the meter movement (so they seem to short it out in each polarity). The diodes need about 0.7 volts before they conduct and as the full scale voltage across the meter movement is only about 0.1 volt, the diodes don't affect normal operation. However in case of severe overload the diodes turn on and limit the maximum meter voltage to less than 1 volt. While this is a heavy overload it gives the movement a good chance of survival and although resistors, etc. might need replacing it's easier and cheaper than the meter. This is usual practice on commercial meters now.
Don Black.

: Hi Kendder

: You will need to know meter sensitivity to determine series resistance to measure voltage. Sometimes it's marked on the meter dial faceplate. A meter with 1 ma full scale requires 1000 ohms to read 1 volt full scale. If you want a 1 ma meter to read 100 volts the series resistor will need to be 100,000 ohms.

: If your meter is 100 micro amp multiply resistance values by 10..

: If you are planning on having a current meter internal meter resistance needs to be known. In this case it may be best to shunt the meter with a very low value resistor. Try 1 ohm and see what current your meter reads.

: Norm

:

: : looking for info on the weston model 301 meters as i have just gotten a half completed power supply using these meters and dont wish to damage them