This is our question :
Design an analog multimeter with a panel meter that has a full scale deflection dc voltage rating of 15V and an internal coil resistance fo 100Ω. The multimeter must be able to measure :
1) voltage range from 1mV to 1000V
2) current range from 10mA to 5A and
3) resistance range from 0.1Ω to 100MΩ
Describe in detail all the designing steps and calculations
MY problem is
For the Voltmeter design
http://www.allaboutcircuits.com/vol_1/chpt_8/2.html
the site only shows us how we can add mutiplier resistors to measure bigger voltages, but how about smaller voltages ;
in my case 1.5 mV to 0.15V ?
tried adding parallel resistors, but this only divides the current and the voltage remains the same,
we need a I = 0.15Ampere for full scale deflection (fsd) but adding parallel, the current that passes through the internal coil resistance of meter is too small therefore only a small deflection will be seen (not sensitive)
how do i solve this? diagrams would be much appreciated =)
Design an analog multimeter with a panel meter that has a full scale deflection dc voltage rating of 15V and an internal coil resistance fo 100Ω. The multimeter must be able to measure :
1) voltage range from 1mV to 1000V
2) current range from 10mA to 5A and
3) resistance range from 0.1Ω to 100MΩ
Describe in detail all the designing steps and calculations
MY problem is
For the Voltmeter design
http://www.allaboutcircuits.com/vol_1/chpt_8/2.html
the site only shows us how we can add mutiplier resistors to measure bigger voltages, but how about smaller voltages ;
in my case 1.5 mV to 0.15V ?
tried adding parallel resistors, but this only divides the current and the voltage remains the same,
we need a I = 0.15Ampere for full scale deflection (fsd) but adding parallel, the current that passes through the internal coil resistance of meter is too small therefore only a small deflection will be seen (not sensitive)
how do i solve this? diagrams would be much appreciated =)