Sciencemadness Discussion Board

Get your coil winder out of the garage...

The WiZard is In - 25-5-2011 at 05:07

Tesla coils electrify epic music remix - Yahoo! News

http://news.yahoo.com/s/yblog_technews/20110525/tc_yblog_tec...

I would like to hear/see Ravel's Bolero, Wagner's
The Ride of the Valkyries, Tchaikovsky – 1812 Overture....

Mr. Wizard - 25-5-2011 at 07:16

There is something oxymoronic about playing rap on a tesla coil.

Did they use an audio amplifier to modulate the RF frequency that drove the coils? Following on with that idea, would SSB (Single Side Band) give a cleaner sound than regular AM ( Amplitude Modulation).

The WiZard is In - 25-5-2011 at 08:10

Quote: Originally posted by Mr. Wizard  
There is something oxymoronic about playing rap on a tesla coil.

Did they use an audio amplifier to modulate the RF frequency that drove the coils? Following on with that idea, would SSB (Single Side Band) give a cleaner sound than regular AM ( Amplitude Modulation).

Human's cannot hear SSB. Unless perhaps you drill a hole
in you skull and crazy-glue in a tunning fork.

The sole advantage of SSB/SSB suppressed carrier is for
over the air/wire line transmission.

With AM the VF if impressed on the carrier frequency. Thus
1 000 cps on a 10 Mhz carrier signal consist of the 10 Mhz
carrier, a 10 Mhz + 1 000 cps upper sideband and a
10 Mhz - 1 000 cps lower side band. Your 1 000 cps
now requires 2 000 cps bandwidth, thus SSB carriers
were used in telephony as they required 1/2 the bandwidth,
i.e., you could get 2X number of voice channel on a wire pair.
"K 1+2" carrier was a 12 channel SSB carrier system.
Born ca. 1938, died ca. late 70's. [?]

For radio transmission the advantage of SSB over AM was power.
In a 50 000 watt AM signal... 25 000 watts is transmitted as unless
carrier i.e., it carries no information, 12 500 watts each
transmitted as upper and lower sidebands, i.e., you now have two
copies of the information at the receiving end. With SSB all 50 000
watts is signal intelligence. The carrier being reinserted at the
receiving end.

There is no quality advantage to SSB, FM has better quality due to
its greater bandwidth, which is only available at the high frequencies it is transmitted on.

I should add .. SSB power is measured as peak to peak
power. If you check the voltage with you VOM from an outlet
it is usually 120 VAC RMS Root mean square
i.e., effective voltage, i.e, 2 it it will do the same amount of
work that matching DC voltage (power) will do. The actual
(peak to peak) voltage is 1.414 time the RMS voltage. Or
the RMS is 0.707 X the PP voltage.

(Not that anyone rally cares - I would mention in passing that
noise is measured RSS Root Sum Squared. I could probable
pony up a mathematical explanation....!)



[Edited on 25-5-2011 by The WiZard is In]

[Edited on 25-5-2011 by The WiZard is In]

Mr. Wizard - 25-5-2011 at 22:53

Although we can't 'hear' SSB,as you mention, the USB output of the 10 MHz carrier and the 1000Hz audio would be a more pure 10.01MHz rather than the mix of 10.01MHz and 9.99MHz. The only reason I mention it is we obviously hear something from the Tesla coil. The coil is operating at a frequency above our hearing range. Whatever mechanism produces the sound we hear, it would seem a pure tone would be more euphonic than two separate frequencies.

Could the modulation of the RF in the discharge of the coil cut the current to zero? This would have the effect of causing air to conduct and expand during the audio cycles, and giving pulses of pressure to the air? As the audio drops to zero, it cuts the current, and the arc quenches itself, only to start again with the next audio cycle or negative pulse. In this method, a close gap would be required to allow an arc to always form, but far enough apart to always quench. They have an extension on one of the spheres to allow this.