bigal_scorpio
Active Member
Hi to all,
Just having one of my stupid days and can't remember how I used to change the scale of meters to suit the range of measurement.
The meter I have is a small moving coil one with a scale of 0 to 500mA but the load I need to measure is between 1 and 5A. I seem to remember that I need to put another resistance in parallel with the coil to take the lions share of the current but therein lies the problem. If I am correct in thinking the new resistance would need to be roughly 1 tenth of the original coil resistance then I will be stuck since the coil seems to measure around .5r then I would need a resistor of 0.05r. If so then I have nothing so small.
Have I got this right? Also it would help to have a little adjustment available to calibrate the meter, but again if my values are correct I am struggling to find anything small enough.
Al
Just having one of my stupid days and can't remember how I used to change the scale of meters to suit the range of measurement.
The meter I have is a small moving coil one with a scale of 0 to 500mA but the load I need to measure is between 1 and 5A. I seem to remember that I need to put another resistance in parallel with the coil to take the lions share of the current but therein lies the problem. If I am correct in thinking the new resistance would need to be roughly 1 tenth of the original coil resistance then I will be stuck since the coil seems to measure around .5r then I would need a resistor of 0.05r. If so then I have nothing so small.
Have I got this right? Also it would help to have a little adjustment available to calibrate the meter, but again if my values are correct I am struggling to find anything small enough.
Al