Progress Update:
I have to bust the bubble of those who planned to do calibrating their tach on the cheap. Using the downloaded NCH (
NCH Corporation) software and the sound card in your PC or laptop
does not work.
Here’s why:
The tach input expects a square ware with a minimum of 9 volts peak to peak. The tach doesn’t stabilize until the voltage gets up to 10 volts peak to peak or higher.
The sound card output was less than 1 volt peak to peak at maximum volume. I hooked in the speaker amplifier and it didn’t do much better. The waveform generated by the sound card was full of distortion and noise. Not enough output voltage to do the job, and terrible signal quality on top of that. The sound card output voltage is a computer industry standard, so looking for a different computer or sound card isn’t likely to give any better results.
I watched the output of the sound card and amplifier on a Tektronix 5400 series oscilloscope to verify the voltage and waveform. The Tektronix scope is old, but very reliable and stable. The calibration is reasonably close, and not a cause for concern in this case.
In case some of you are thinking that I have a junky old PC, and that’s why it didn’t work, guess again. I am using an IBM E205 Eserver, 2.8 GH Pentium 4, 2 GB memory, and WinXP Pro. It may be old but it is very good equipment.
For those of you who have more questions, PM or email me through Stangnet.
I will be doing a full scale bench test using the Tektronix 5400 series oscilloscope, Hickok function generator and Hickok frequency counter. That will insure the accuracy of the results and quality of the finished effort.