I'm looking for a small meter that could be panel mounted or mounted outside a chassis to measure from 0 to 150 mV for setting the current on an output tube. Something more eloquent and permanent than a DMV 🙂
Milkduds
Milkduds
A traditional 1mA 50mV meter movement is 50 ohms coil DCR, it would need 150 Ohms in series with that to make it 200mA full scale.
But that would only be 200 Ohms total resistance, probably too low to put in parallel with the cathode self bias resistor.
A 100uA meter movement might be more suitable. 50mV/100uA would be coil of 500 ohms. if the meter has 500 ohms coil DCR, then 1500 Ohms in series with the meter would make the meter 0-200mV.
You need to know the DCR of a current meter, and calculate the necessary series resistor to make the effective scale 0-200mV.
But that would only be 200 Ohms total resistance, probably too low to put in parallel with the cathode self bias resistor.
A 100uA meter movement might be more suitable. 50mV/100uA would be coil of 500 ohms. if the meter has 500 ohms coil DCR, then 1500 Ohms in series with the meter would make the meter 0-200mV.
You need to know the DCR of a current meter, and calculate the necessary series resistor to make the effective scale 0-200mV.