Peter Davey Heater

[devrimogun]

The frequency is simply the frequency of the experimentators AC mains supply
(or an octave of it).
Paul.

Yes there is no doubt about it.
I meant to ask if both are the same frequency?

[Paul-R]

Yes there is no doubt about it.
I meant to ask if both are the same frequency?

Yes. both bells are tuned to the fr4quency of your AC mains, or
an octave.

[forest]

How to tune them ? I can't imagine tuning while connected to mains... Do you really think that AC current produce a sound while passing through conductor ? Then why I don't hear any sound  in my wall socket ?

[edelind]

How to tune them ? I can't imagine tuning while connected to mains... Do you really think that AC current produce a sound while passing through conductor ? Then why I don't hear any sound  in my wall socket ?

The easiest way to do it (for the rest of us, non-musicians) is to use computer software to analyze the sound the bell emits. From my experience it is the same as the frequency it resonates.

As a software, you can use Audacity or Spectrogram. After you see the frequency (frequencies)  your bell is emitting when hit, you can machine it gradually until you reach the desired harmonic of the mains.

You can check your resonance by using a sound frequency software generator, like PAS Frequency Generator, and put the sound into some large speakers (my portable stereo was enough in my case). Then place the bell as near as possible to the speakers and tune the software emitted frequency around your bell's frequency. If you cannot feel the vibration in your hand at resonance (as you definitely won't be able to hear it), you can place a small plied piece of paper on the bell's edge (keep the bell with the edges on top). You will see the paper starting to "dance" or even jumping out of the edge when you reach resonance. The only problem with this software generator is that you can only adjust with integer hertz values, which is a real problem for reaching a perfect resonance. But it will still work.

Please note that a lose bell will have a slight different frequency that the same one hard connected to a rod.

[forest]

Thank you. That was very useful information about how to tune bells to resonance with MECHANICALLY caused resonance. The point is that I don't believe AC current simply put through bells will force them to vibrate! There is some trick here, maybe related to loosely mounted bells.Maybe those bells are in such position then they create a circuit shortcut for a very small period and the arc produced is acting on them mechanically... As I mentioned I found a patent which describe similar device in shape, but vibrations there are produced by pulses from HV capacitor discharge