What causes it?

S

shortbus=

Well-Known Member

Most Helpful Member

• Dec 16, 2009

• #1

In movies or TV shows, when the crime scene people are taking photos, they snap a picture and there is a "whining" sound afterward. Not the film advancing but a higher pitched whine. What is causing that?

My guess is the flash caps recharging. But why is it making a noise?

 

audioguru

Well-Known Member

Most Helpful Member

• Dec 16, 2009

• #2

The oscillator that produces the high voltage in a flash circuit makes an audible frequency of about 2kHz. The laminations of the transformer vibrate when the high current goes through the coils.

 

B

BrownOut

Banned

• Dec 16, 2009

• #3

My old flash unit would start at a lower ( but still pretty high ) frequency and the tone would get higher as it charges, until the "ready" light would come on.

 

audioguru

Well-Known Member

Most Helpful Member

• Dec 16, 2009

• #4

When the big capacitor is discharged then its charging current from the oscillator is high so the oscillator's frequency is low. Then as the capacitor charges its charging current becomes less and the oscillator is not stuggling so much so its frequency gets higher.

 

M

mneary

New Member

• Dec 23, 2009

• #5

In movies or TV shows, when the crime scene people are taking photos, they snap a picture and there is a "whining" sound afterward.

Click to expand...

It's art, not reality. Look up Foley artist - Wikipedia, the free encyclopedia. There is probably one "camera sound" that everybody licenses for their films.

 

C

Conrad Hoffman

New Member

• Dec 24, 2009

• #6

Pretty much everything you've learned about anything from TV is wrong, with the exception of PBS. That goes twice for tools and technology. Ever notice how anybody not associated with the crime lab, who has an interest in electronics, tools or computers, is usually evil in some way?

 

killivolt

Well-Known Member

• Dec 24, 2009

• #7

Let me start by....... wickedly laughing.

The same thing happens when a television won't oscillate.

Or when little green men attach themselves to HV.

Which gives them their iridescent glow.


**broken link removed**



kv