Mechanical Resonance (Projects)

[Magluvin]

Im getting 4vpp at 10.58hz with the 2 coils in series as pickup coils at full throw resonance using the drill to motivate the pendulum. Full throw is the stainless plate hitting the kapton bobbin of the speaker coils. The drill magnet seems to have very little affect on the coils so Id say good test. Also tried shorting the coils in series while driving the pendulum with the drill.  It has some resistance against the oscillation but less than I imagined. It doesnt kill it off thats for sure. Have some stuff I gotta do and I will apply electrical input tonight. Want to try low duty cycle pulses also.

Was thinking to use the original speaker magnets and mount the coils to the pendulum, but the angle change as the pen swings, and limited travel staved me off the idea. But we do need to look at closing a magnetic path between the coils and magnets to get better generator/motor effects, rather than open as we have them.

I have some carbon fiber tubing I want to try later on to replace the stainless plate. I get a lot of breeze like a fan when in full throw resonance with the plate, so want to eliminate some of that loss.  Will probably have to use 2 pieces of carbon tube with attachments at the top to keep it going back and forth instead of possible circular wobble with just 1 rod.

Mags

[Magluvin]

When you talk about using another coil to redirect the PM's field,the first thing that comes to my mind is the MEG,as that is exactly what it dose--uses a second coil to redirect the PMs field into a drive coil--or main coil.

Exactly. May as well just use the coils field directly without the magnet.

Mags

[Magluvin]

Well I played with the pendulum some tonight using the coils to drive it. There are issues with having coils as I did. The larger thin disk mags go beyond the coil. So if the coil is still in pulling mode, when the mag passes tdc the input wants to restrict further movement because the coil applies attraction also after tdc. When I get it going with the drill and the moving strip is just hitting the bobbins lightly, there is a dip in the peaks, showing a current reversal since the mag is on the other side of tdc for a bit.

So ill do a vid tomorrow of things as it is and just limit the input and movement of the mag at tdc. Ill be using my android smart phone with the app Kewl Dual Channel Function Generator.  The freq adjustment goes down to 1 milli hz. Crazy. And to the 3rd decimal place. My amplifier most likely wont play that low, but works great for these low freq. Sine is clean. Anyway....

Remember how Brads device shook the whole bench?  Well mine is kinda undetectable in that sense at 10hz, but the whole device and base shake. When I hold it down tight the pendulum moves further by eliminating most of that loss. 

Another thing with the coils and mags is the orientation of the mag produces weaker field at the coils than if the field were concentrated across the coils from inside the bobbin to the outside dia of the coils, like a speaker magnet assy does. So efficiency is low in that area also. If the coils were in the speaker mags, I would need way less power in to get the same results. Gotta think on that one.   The magnetic gap of the speaker mag assy is a bit shorter than the coil length. So like a speaker, Xmax, the distance in mm of total distance of coil travel with the coil still in the gap. So this may be possible with a shorter pendulum where we get higher freq and less distance of travel like Brad had shown.

But will still do a vid on this before the next mod. Still playing with things to have a short list of interesting things to show.

Mags

[Magluvin]

Just found something that is an issue also.  The speaker are the fr and rear 6.5in mids from the front doors and rear side panels. Truns out I didnt notice that and one coil is from the rear and one coil is from the front. One coil is 8 ohm and one coil is 4 ohm.  So that why while touching the driven coils with my finger, one was warmer than the other. . Lol.  I assumed they were all 4 ohm as it said on the back of one of the speakers. So putting them in series is bogus really.

Cutting out the 'real' 4 ohm and fitting to the coil holder now... Lol now my script is messed up. I had it where there was 8v ac input to the 2 coils in series, came out to 8w and 5.6w rms. la dee da.

Anyway..... Never seen same looking speakers in a car that were different ohms.  Crap, some put 2ohm in for more sound from a 12v simplified amp without the step up power supply.

So that what Im doing here at the moment.


Mags

[Magluvin]

Ok, lol, OK, I see I start my videos that way. OK! 

https://www.youtube.com/watch?v=5Fmmg9UXnw4&feature=youtu.be

Mags