hoola

I ordered ten 7014 ICs from Newark Electronics (formerly MCM) and all were defective. Under close examination the logo is blurry and indistinct. I have ordered most of the parts for this project from them with no other problems. Last week I re-ordered ten more 4017s online from Amazon, got them today with a Texas Instrument logo that is clear, and the first three I have tried work correctly both in the solderless breadboard and the prototype board.

well, there is no reverse scan in the present scheme...should have said " thrust in the direction opposite of forward scan".

early mechanical experiments indicated the possibility of scavenging the return energy by dumping the reverse shock wave into a dummy load resistor. I did get some interesting waveforms across this load that were trapezoidal (sloping square wave) and very regular and that didn't change waveform when slowing down the stimulation. By adjusting tensioner nut on the center pin thus adjusting mechanical pressure on each element, a sweet spot was found indicated by a moderate compression that produced maximum voltage output on the scavenged signal. (The woodward crowd glues and clamps each element very solidly and I think that is a problem. The elements must be allowed to move, or the shock wave is largely converted into useless harmonics). But this dummy load was only a passive load to the unwanted shock wave, so I have the active neg feedback system which should be more effective in nulling the retrace wave. A possible way of upping the efficiency might be to try to hit each piezo, then hold the volatage on each one to the end of forward scan, then drop the voltage serially, as the shock wave travels back, thus absorbing it as much as possible within each piezo, instead of neutralizing it with the neg feedback electostriction. As the reverse wave hits each piezo, it's loss of voltage will not only shrink in the needed direction, but the wave may compress the element slightly as it passes, thus generating a voltage that could be recycled into the next forward scan sequence. This form of retrace period might require a higher scan rate, as the piezos will collapse even if the voltage is held steady and physically self-compress at the 25khz time constant (resonance) and so require a doubly accurate pulse timing management. The first electronic experiments will drive the stack until the temperature stabilizes, then turning on the neg feedback system. At that point an increase in temp would seem to indicate that the return wave is being converted to heat through electrostriction...thus the possibility of thrust in the direction of reverse scan. Still waiting for the 4017 parts, hope the corona thing doesn't significantly delay delivery.

Actually the pan balance test isn't quite so simple. A laser pointer is aimed at a mirror placed on the scale with an acute angle, and the beam is reflected onto a distant surface to display amplified small movements.

I have abandoned the arduino as a trigger for the pulse delivery system due to it's apparent inability to deliver pulsed output in a microsecond range serially over the pwm ports. It does seem apparent that each one millisecond time division can be divided more finely with a hack I found online, but that seems unhelpful. I have been given a 4017 chip based design that could be capable of the needed output. It may prove easier to build what I need than to find something off the shelf. I have also decided to skip the pendulum idea of detection for the moment which has proven unwieldy, and will static mount the stack to start powered experiments with the goal of merging 5 small pulses into 1 large pulse, while keeping overall input power to a minimum. I have also had difficulty in the 25khz trap idea, but have found a circuit called the twin tee that does not use an inductor, only R and C components, that can be incorporated with a non inverting op amp to deliver accurate and deep rejection of a specific frequency. That is an option that can be easily added later and not necessary for the static mount tests. If the static tests prove positive, a simple pan balance setup to see if weight differences occur on a vertically mounted stack will be tried.

I need to know the fastest switching speed an arduino can produce. After numerous utube tutorials and asking around, no one knows what that is. The reason I need to know is that the shock wave travelling through the stack will have to be " chased" in the manner previously described, and it seems likely that since the stack is on the order of 2" long and having a far faster speed of sound being a dense ceramic, will need microsecond gradations, and not the millisecond pulse rates that the arduino might only be capable of. If the arduino speed is limited to a millisecond range, a recommendation of a laptop controlled microcontoller with a microsecond control speed would be very much appreciated.

The drive order at each limit of swing is switched in either instance. The stack will be suspended from the ceiling with two parallel fishing lines spaced equally to the distance between stack end attachment points to keep the assembly parallel to the proposed thrust vector.

the question of how to detect micro newtons of thrust is going to be a tough one for a table top experiment in the kitchen. I am going to try swinging the stack as a long pendulum of approx 55" of length, suspended from the ceiling with fishing line. I will time the duration of the swinging without power until the mass comes to rest. Then I will power up the stack and measure swing duration with the proposed thrust direction positive to the pendulum directions. Then thrust direction will be reversed to counter the pendulum motions and that will be timed. These 3 tests averaged over many trials might offer some evidence of thrust or lack of it.

a purely mechanical system is what I am experimenting with now, using a double row of 24 contacts rotary switch spinning at 1800 rpm , sweep pulsing the piezos and scoping results with a 6th piezo at the end of the stack. I am in the process of assembling a purely electronic setup using an arduino microcontoller to manage timing of the 5 power amps that will pulse each element individually, with the next pulse timed precisely to reinforce the previous one in the forward direction, or hit it at the next element's "TDC". This hopefully will result in amplification of the pulse that after 5 repeated steps hits the end of the stack, and due to mechanical impedance mismatch, is reflected back in a way similar to a transmission line or an audio amp that has lost it's load. This reflected wave is the problem. It prevents thrust by equalizing forces. The driver schematic I am drawing up has a full time negative feedback system, but with a hi Q 25khz trap in series, which is the resonant frequency of the piezos I am using. This will suppress the normal sideband noise but not the desired signal. This could clean up the carrier signal and maybe even offer some added amplification due to reduced internal losses. At the end of the cycle, when the return wave is heading back through the stack, all feedback circuits remain on, but the 25khz trap is bypassed and all signals are suppressed maximally within each element. This hopefully will cancel a portion of the reflected wave energy within each element. So, the overall goal is to amplify kinetic forces in one direction and actively suppress it in the other.

substances don't absorb force? Wouldn't an absorbed force show up (at least)as heat within the material? The domed spring idea is interesting if it produces a diode like appearance to the system. The "thing" the spring is set against in this instance would be the inherent mass of the ring, but even then it seems the dome would couple as much energy overall in one direction than the other, although I see it might have a differing directional profile. If you had maxwell demons to do the job, such as tiny trap doors that all open in one direction allowing force through and close in the other, blocking such efforts with compressive release of heat from the stopped wave .

does anyone know of a rubberlike substance with a tailored characteristic that passes a mechanical force in one direction, and absorbs force from the opposite direction? In effect a non linear stiffness profile, or "smart rubber". A material of this nature could act as a rectifier of physical forces, and this directionality might offer a thrust potential when placed between each piezo instead of a single conventional damper used in the woodward mechanism.

I am working with piezo ceramics, 5.5 mm thick. I need to know the rate of a shock wave as it travels through the material. James Woodward, et al are developing a piezoelectric Mach thruster device they are claiming develops propellantless thrust as a physical analog to the Shawyer engine. The materials to do a few simple tests are cheaply available so I figure it could be an interesting side project. Thanks for any help if you know that detail about ceramic piezos or have an interest in mach thrusters in general.

fascism ( Mussellini said it should be called corporotism) is at a tipping point of failure, for economic ( banks too big to fail), coupled with environmental factors (Exon, BP, etc.). Like dying dinosaurs, the rush limbaughs scream into their microphones as the giant comet of reality pays a visit...

when I said the remark about niclola tesla and the "flying pigs" I was using that as an example...who knows if tesla ever imagined in his mind a flying pig...his "flying pig" was the desire to send heavy electical currents through the air without wires.... and his undoing, as the early successes with the AC motor were squandered on this, plus he could have beaten marconi to the punch on radio if he hadn't wasted his time with the idea...as far as dealing directly with the forum topic, I see anything one can imagine as being within the IBH (informational black hole) and we can only imagine or express what is within that. The IBH created the universe in math terms, and is nearly infinite, which allows any sentience to have a not quite infinite imagination. This puts a cap on free will, which relates to the question "if I can imagine it-it-is -possible" is really asking. An act of free will is to imagine real or impossible things. The ultimate act of free will is to imagine things not yet described by the IBH...a seemingly impossible task...

if you can imagine it, it is possible (to imagine it), and even then you are only a reflector with a cloudy mirror...

I agree with the topic "if I can imagine it, it is possible".....on both phases....sometime a "real" thing can be built using a thought experiment as a guide in physical construction. This is how Tesla supposedly invented the AC motor with his imaginings of a rotating magnetic field....so that is possible. When the other side of the subject is considered, it still remains true,....examining the statement, using a strict semantic definition of "if I can imagine it, it is possible", then the statement is true still as reads...."If I can imagine it, it is possible... to imagine it"...this includes any sort of perpetual motion machine, flying pigs, etc. In a legal-istic fancy footwork style, the thread starter used a partial statement, of which people filled in with what is presumed the author meant....very funny....and explains the puzzling success of the advertising industry, and why propaganda works......edd