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Author Topic: Piezo Buzzer ( 2 - 6 MegaHertz) Pulsed Output  (Read 1243 times)
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Hi,

I need to produce a Pulsed 2 -6 MegaHertz output to set up plate resonanace in Lead Acid Batteries.
For example I would have 60 seconds at 2 MHz then 60 seconds at 3 MHz then 60 seconds at 4 Mhz etc.
then repeat again. Also a random Mhz 2-6  so 4 ,2 6, 5 etc. all for 60 seconds.
Probaly with PWM

Can I use a piezo buzzer for this?
And any ideas on the basic code to generate a Mhz value please?

Thanks

jB  smiley-cool
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Sounds like you want to create an oscillator. You could set that up using an NE555 timer and a couple of external components.

If you want to make your Arduino output that frequency directly, it would probably require configuring one of the hardware timers (and I don't know enough about those to say whether that frequency is achievable).

You haven't said what you want to do with that frequency signal i.e. how it gets applied to the battery. I suppose you'd be switching current or something, and doing that at megahertz probably introduces challenges of its own. I can't imagine how a piezo buzzer would help you with that unless you were planning to physically vibrate the battery - and doing that at megahertz frequencies sounds rather difficult.
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Hi,

I was hoping that I could affix the PB to the side of the battery towards the bottom and induce a resonnance into the battery.
I do not think that either me or the battery system is up to being done via elec-trickery at this stage, it would probably interfere with Inverter / Charger system, so sound was my first thought.

I had looked at http://www.reuk.co.uk/Battery-Desulfation.htm which I may venture towards in later life.

Any other help gratefully received.
Thanks and kind regards,

jB  smiley-cool
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I can't think of a single physical system that will have resonance in the Mega Hertz range...  You will certainly NOT get a piezo element to vibrate at that range.

On looking at the web site you provided, I am suspicious that if the process actually works it is likely NOT using resonance to accomplish its task.  I would suggest looking for peer reviewed academic papers on the subject, I suspect this may be of the same caliber as perpetual energy and other wild claims.

Either way the frequencies (2,000,000 - 6,000,000 Hz) are well above the range of sound (0 - ~ 50,000 Hz).  You can directly feed frequencies of the former range into a battery, but as I have said, I have strong doubts it would do much, and am fairly certain it will not induce "resonance"
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Quartz can vibrate at those speeds easily because it is piezoelectric, but it's a small vibration.

Ceramic can get some pretty high frequencies too so might make a way to get the vibration into the acid.

Stirring does speed reactions in solution....



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On looking at the web site you provided, I am suspicious that if the process actually works it is likely NOT using resonance to accomplish its task.  I would suggest looking for peer reviewed academic papers on the subject, I suspect this may be of the same caliber as perpetual energy and other wild claims.

I can't personally attest to the efficacy of this particular circuit, but lead acid battery desulfation is a very real and established process.  However, you are correct it doesn't involve physical vibrations, just quick-cycled high current pulses through the battery.  The schematic in the link doesn't contain any speakers or similar components, so I think britesc just misunderstood what was going on.
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I was hoping that I could affix the PB to the side of the battery towards the bottom and induce a resonnance into the battery.

The pseudo-science on that site did not look very convincing to me, but what they were talking about was applying a high frequency electrical AC signal, not a mechanical vibration. Trying to get an electrical oscillation in the megahertz range with any significant voltage or current strikes me as rather difficult and I'm not convinced it's feasible without some rather specialised equipment.

The process of desulphating lead-acid batteries is not novel and usually just involves adding a few pills into the electrolyte and then discharging and recharging the battery a few times. Using an AC component on top of a DC charging current was proposed several decades ago as a way to recharge zinc-carbon cells that were not normally considered rechargeable, it was not very effective under ideal conditions and not really of any practical use. I suspect that's where the inspiration for this new multi-megahertz process came from, though.
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Piezo transducers are I think an irrelevance here - the idea is applying a high frequency current to a suphated lead-acid battery to help break down the lead-sulphate crystals - I don't know if this really works but you'd need to modulate the charging current directly at these high frequencies so a very fast MOSFET switch is probably needed, something like 50ns switching times at several amps or such.

The timer units can generate upto 8MHz from a 16MHz clocked Arduino, the period being a multiple of 2 or more 62.5ns periods (8, 5.33, 4, 3.2, 2.67, 2.29, 2MHz).  Such a signal would need to be boosted through a high speed MOSFET driver chip to a high speed MOSFET switch (you need a MOSFET capable of carrying the current needed without overheating, but with as low a gate capacitance as possible to achieve this).

Code:
void setup ()
{
  pinMode (9, OUTPUT) ;  // use pin 9 for timer1
  TCCR1A = 0x82 ;      // setup programmable frequency and duty cycle mode
  TCCR1B = 0x19 ;      // fastest clocking, full clock rate
  ICR1  = 0x0001 ;      // set TOP - the counter cycles from 0 to this value then wraps again, here 0 to 1 to 0 to 1 etc
  OCR1A = 0x0000 ;   // set threshold, should be ICR1's value integer divided by 2
  TCNT1 = 0x0000 ;    // set starting count to 0
}
Will give 8MHz on pin 9.  For 5.33MHz you'd change ICR1 to 2, for 4MHz you'd change ICR1 to 3, OCR1A to 1
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Quartz can vibrate at those speeds easily because it is piezoelectric, but it's a small vibration.

Ceramic can get some pretty high frequencies too so might make a way to get the vibration into the acid.

Stirring does speed reactions in solution....

It is not simply the material that vibrates,  For instance you simply can't cause a 30 pound chunk of quartz to vibrate at Megahertz frequencies.  I admit I wasn't as precise as I should have been when I made the claim that physical resonance wouldn't have occurred at those frequencies, but something the size of a lead acid battery is not going to resonate, much less vibrate (physical movement) at those frequencies.

I've looked for academic articles (briefly) on the subject of desulfication using resonance and could not find any...
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The less than 30 lb piece of quartz on my Arduino oscillates physically 1t 16 MHz... make of it what you will.

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The less than 30 lb piece of quartz on my Arduino oscillates physically 1t 16 MHz... make of it what you will.



The piece of quartz in your oscillator masses much less than a fraction of a single gram...  Explain to me how your going to get a quartz crystal to vibrate at millions of hertz, much less resonate at those frequencies...  My understanding is that the physical size/shape of the crystal is critical to tuning it for a given frequency...

And of course that says nothing about resonating a 30+ pound composite object like a battery at millions of cycles per second...
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I never said it would. I never said it would be practical. Only that the quartz can resonate at MHz frequencies.



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