Yes, we can adjust the Q of the piezo's self-resonance by damping and, maybe have some control over the load's resonances. But to know what we're looking for, you are correct, I should do the the Thiele-Small analysis. I looked at it a bit and do think it is applicable - coupling of two...
Hey, here is a piece of news. I spoke with a technical sales manager at one of the well-known RF inductive heating companies (company name withheld in case it is against forum rules or detrimental to that company), and he said that they do NOT want to operate exactly at peak resonance. As the...
Hmmmm. No, I convinced myself that the two resonances, the piezo's and the medium's, if close enough in frequency, would "compromise" to one intermediate frequency, if I put the piezo (and its "load", the medium) into an appropriate tank circuit. You convinced me that an appropriate tank...
More good advice from experience - thanks.
The only thing that might make my piezo application a little special is that there are essentially two mechanical resonances in the system. One is the obvious plate-thickness resonance of the piezo slab itself. The other is in the acoustic medium...
Warpspeed,
Thanks again for even more useful info.
BRICK linear amplifiers: I have RFQs out for a couple, just to get an idea of price, but I think I am convinced to go with the FET-switched resonant tank, digitally.
CORRECTION: My load is actually a piezoelectric ultrasonic...
Nevermind about the request for "brick" amplifier. I searched a bit and found a couple of vendors. If interested, see atttached PDF spec sheet and let me know if that is NOT what you had in...
Warpspeed, Absolutely good idea, to put an inductor in series to make the raw DC supply a constant-current-seeking source. I like to think I or my eectrical guys (I am a materials scientist) would have thought of that. In the past I recall EEs I have worked with worrying about a huge forward...
Warpspeed, Thanks for the detailed explanation.
Analog: Can you point to sources for "brick" amplifiers in the 1 MHz, 200 watt range?
Digital: You mention "Tank oscillation amplitude still needs to be controlled, and that can be done by pulse width modulating the drive to the tank." That's...
Warpspeed,
Thank you so much for your posts. I did research the RF inductive heater power supply arena as you (and electricuwe) said, and I saw that frequency following is indeed available. I was just about to ask you some details of your idea to "use the self resonance characteristics of...
Thanks for encouraging suggestions!
Now that I think back, I recall a project going on a place of former employment, though I was not involved directly, where engineers were driving a gaseous plasma load in vacuum using an RF inductive coil. Of course, the impedance/reactance of this plasma...
I need to drive about 100 watts of RF power @ 1 MHz into a moderately resonant load (estimate Q ~ 100 - 300) whose center frequency or "desired" resonant frequency drifts. I want to (or have to) let it drift and change my drive frequency to match. Else I won't get power to couple.
I am at...
