![]() controller mounted
under dashboard |
Oscilloscope View of
Controller's Output at Various Angles ![]() zero degs. / zero volts
|
![]() 15 degs. / 2.9 volts
|
![]() 20 degs. / 6.3 volts
|
![]() 35 degs. / 12.1 volts
scope limitation does not show voltage going to zero |
Measuring Pulse Width Modulation 'Voltage' with a Digital Voltmeter
While conducting these experiments I determined that it is possible to use a digital voltmeter to measure pulse width integral voltage. Initially I was unsure that I could do this, because the digital voltmeter repeatedly samples the circuit and then interprets the result in the display. I could imagine a hit-and-miss situation as the digital volt meter sampled the pulse when it was either zero or maximum; resulting in readings that flick from 0 to about 12 volts - or maybe something else in between. But this did not happen, at least with the 3,100 Hertz frequency of the Voyager. I checked the digital voltmeter’s readings with various pulse proportions seen on the oscilloscope, and they seemed to match. I made similar measurements with another digital voltmeter and with an analog voltmeter; they were all in agreement. With this background I felt confident in using a digital voltmeter to take voltage measurements for this project. |
Test Rig for Tilting the Voyager and Making Voltage and Temperature Measurements ![]() test rig, front view
meter on left measures temperature meter on right, output voltage box at rear is power supply |
![]() test rig, back view
temperature probe is under polyester wad |
![]() test rig, angle pointer
|
Output Voltage Measurements at Various Angles and/or Temperatures GRAPH 1 ![]() output voltage at various angles for
five temperature ranges (see text) gain and level controls each set to one-half |
GRAPH 2![]() output voltage for temperature
range of 48 to 99 degrees gain set at one-half level control set at neutral (see text) |
Temp. F. 47-51 58-64 71-75 84-89 95-100 |
Voltage 3.83 5.01 5.25 6.58* 6.06* *see text |