Texasmark
Supreme Mariner
- Joined
- Dec 20, 2005
- Messages
- 14,793
Baloney. a DVA is a Digital Voltage Adapter.
The High voltage pulses generated to operate the CDI are very narrow pulses with a long recurrence rate. Like a 1 microsecond pulse occurring at 1000 rpm (1 millisecond time interval) is a 1000-1 ratio...micro sec to milli second. Unless you had an oscilloscope or a sample and hold circuit you could not measure anything.
The DVA is a rectifier, for DC, a storage capacitor, and a large bleeder for eventually bleeding the charge off the capacitor for another reading of lesser value if that were required. The rectified DC pulse charges the capacitor and over thousands of pulses...a minutes running time, the capacitor has had enough pulses to fill it with energy equal to the peak of the pulses applied. Hanging a meter probe across that is easily read. Readings from the DVA are in 100's of Volts, not Ohms, but both can be read with the same DMM.
The stator resistance is a continuous DC reading....you are measuring the resistance of a piece of copper wire.
On accuracy, back in the old days of the D'Arsonval, jeweled, meter movement, like came in a Simpson Analog Multimeter, the sensitivity was in the order of 10k or 20k ohms/volt input impedance, meaning the loading effect the meter input circuit could have on the reading, causing a measurement error.
In those days a Vacuum Tube Voltmeter was required to isolate the reading instrument from the circuit as you were feeding the grid of a vacuum tube which was operated in the cut off region....grid draws no current so an imput impedance of 1 million (Meg) Ohms input impedance was the norm which wouldn't affect most circuits, and was a reliable reading.
With today's DMMs, that impedance is on the order of 10 Meg Ohms, and digital signals are 1 or 0, nor 1.15 or 0.75 type things common to analog instruments, another benefit to accuracy of DMMs.
) or I'm missing the boat here?