Headset Noise

Mike,

Thanks for publishing the alternator simulations. I found them very
interesting.

You said, "... with six intact diodes, the fundamental frequency of the
ripple is six times the rotation rate."

I read the fundamental ripple frequency as 3 kHz. If that's six times the
rotation rate, then the rotation rate must be 500 Hz. That's 30,000 rpm.
That doesn't seem reasonable. What am I missing?

Regards,

Jon

In all the years of chasing alternator whine in aircraft audio systems,
it sounded to me that it is at a couple of Khz.

Jon,

If the engine is turning 2600 RPM, that is 43 revs per sec. The pulleys
on the alternator have a ratio of about 4:1, so that would make the
alternator spin at about 173 revs per sec, or 173Hz. That would make
the alternator whine (assuming no bad diodes) of 1038Hz.

I should alter the sinsoidal current sources to have a freq of 173Hz,
instead of the 500Hz I used.

btw- for the electrical geeks out there, you are familiar with LTSpice,
arent you? If not, go look at www.linear.com and get a download. Best
Spice implemenation out there, and it is FREE!

Mike,

Thanks for the clarification and the link to LTSpice!

Jon

"mikem" wrote in message
oups.com...
In all the years of chasing alternator whine in aircraft audio systems,
it sounded to me that it is at a couple of Khz.

Jon,

If the engine is turning 2600 RPM, that is 43 revs per sec. The pulleys
on the alternator have a ratio of about 4:1, so that would make the
alternator spin at about 173 revs per sec, or 173Hz. That would make
the alternator whine (assuming no bad diodes) of 1038Hz.

I should alter the sinsoidal current sources to have a freq of 173Hz,
instead of the 500Hz I used.

btw- for the electrical geeks out there, you are familiar with LTSpice,
arent you? If not, go look at www.linear.com and get a download. Best
Spice implemenation out there, and it is FREE!