Resonance Effects For Everyone To Share

[gyula]

Hi Luc,

Well, you are right on that and I did not really think over the push pull operational needs on the driving signals. What I included in my schematic was a normal inverter stage (as poynt99 also drew it).
I attached a schematic plan that includes two AND and two OR gates and a D flip-flop, all exist in normal CMOS IC types. I took this schematic from the TL494 data sheet, it is part of its inner circuit, named pulse-steering control flip-flop.

If you wish to build this circuit and need help on pin connections and CMOS IC types then I can later do a specific schematic on it, ok?

One question: Among other setups, will you drive also a H-bridge with this LMC555 pulse generator where push-pull drive is also needed?

rgds, Gyula

[ren]

Hi gyula,

check out my waveforms a couple of posts back. Im pretty sure this is what Luc and I are after. Im gonna stick with the TL494 for the moment. I will post a schematic if others want to build and experiment with it. Ive got pulse width sorted out as well as frequency up to about 600kHz. Also looking at dead time control soon.

We basically need two pulses that are out of phase with each other, but never overlap, so we can drive each side of the H bridge or center tapped primary.

The pic I posted shows the sort of wave forms we are after (I think!)

Many thanks

Ren

[gotoluc]

Hi Luc,

Well, you are right on that and I did not really think over the push pull operational needs on the driving signals. What I included in my schematic was a normal inverter stage (as poynt99 also drew it).
I attached a schematic plan that includes two AND and two OR gates and a D flip-flop, all exist in normal CMOS IC types. I took this schematic from the TL494 data sheet, it is part of its inner circuit, named pulse-steering control flip-flop.

If you wish to build this circuit and need help on pin connections and CMOS IC types then I can later do a specific schematic on it, ok?

One question: Among other setups, will you drive also a H-bridge with this LMC555 pulse generator where push-pull drive is also needed?

rgds, Gyula

Hi Gyula,

I have some 4013 flip flop IC's but for some reason even If the duty cycle is lower than 50% lets say it is at 10% the 4013 sill puts out 50% cycles

Is there a way to use two 555 to achieve the flip flop with single duty cycle?

Thanks

luc

[poynt99]

Hi Gyula,

I have some 4013 flip flop IC's but for some reason even If the duty cycle is lower than 50% lets say it is at 10% the 4013 sill puts out 50% cycles

Is there a way to use two 555 to achieve the flip flop with single duty cycle?

Thanks

luc

Luc,

Flip-Flops (FF's) are designed to work that way. Most of them (including the 4013 I think) only care about a rising or falling edge at the clock input. Inherently they put out 1/2 the frequency of your clock input, and it is exactly 50% (fixed) duty cycle.

What is it you guys are trying to design anyway?

.99

[ren]

Hi poynt99.

We are simply looking for a stable PWM to use in resonance experiments which has a broad range of frequency adjustments, pulse width control and dead time if possible. I for one am after a flip flop style output, or one that could drive a center tapped coil or H bridge. So two outputs out of phase that can stimulate a modified sine wave of sorts.

A signal generator has been used in the past to trigger ICs, but ideally we are after a pure DC version, one that people can play with that is fairly simple and doesnt require a sig gen to alter the above variables.

Regards

[Inquorate]

Hi poynt99.

We are simply looking for a stable PWM to use in resonance experiments which has a broad range of frequency adjustments, pulse width control and dead time if possible. I for one am after a flip flop style output, or one that could drive a center tapped coil or H bridge. So two outputs out of phase that can stimulate a modified sine wave of sorts.

A signal generator has been used in the past to trigger ICs, but ideally we are after a pure DC version, one that people can play with that is fairly simple and doesnt require a sig gen to alter the above variables.

Regards

That would be nice

[poynt99]

ren,

What would your desired spec be?

What do you guys mean by "dead time"?

Isn't that related to duty cycle?

So this is mainly for driving MOSFET's and H-bridges?

Why do the off-the-shelf chips not work for you? (there are dozen's to choose from I believe).

.99

[ren]

Poynt99,

the specs are stated above, I have a TL494 doing pretty much all of it already, but its limited to the kHz ranges. Still will probably be all that I need.

Im opto isolating the outputs so I can keep it from popping on higher DC inputs.

My understanding of dead time is the space between the two out of phase pulses. Can be very important with H bridges because any over lap of the signals creates a dead short, and pop goes the weasle. Most chips have a set dead time, but this may need to be altered for certain configurations. This is how I have been taught to understand it. I guess dead time is related to duty cycle in an inverse kind of way, somewhat.

Off the shelf chips most likely DO work for us, its finding one that is simple and allows all of these functions that is the problem for us, not being trained in or familiar with the plethora of options out there.


Im sure for any electrical engineer its a walk in the park, or a trip to the local component store I guess. But for us (well me anyway) we have to search for answers.

Regards
Regards

[gotoluc]

ren,

What would your desired spec be?

What do you guys mean by "dead time"?

Isn't that related to duty cycle?

So this is mainly for driving MOSFET's and H-bridges?

Why do the off-the-shelf chips not work for you? (there are dozen's to choose from I believe).

.99

Hi .99,

thanks for looking at this topic

I started this topic to demonstrate the effects of a coil in Resonance.

When I first started experimenting with coil resonance I was using Square wave output of my SG in Series LC circuits but the 20vpp output my SG was limiting the test results so I asked for help to design a circuit that I could use a DC source of voltages up to 100vdc and make a square wave AC output. Groundloop offered to design a circuit that used my SG to control the frequency to a 4013 to flip flop two IR2103 that controlled 4 mosfet's in an H-Bridge configuration. The circuit works well but has no duty cycle adjustment and is limited to about 60vdc since the IR2103's get hot fast and not because of amps being pulled through since I never needed heat sinks on the mosfet's! I think it was the voltage buildup of the resonating coil (well over 400vpp) coming back in and burning the IR2103's

Anyways, this is the history in a nutshell.

What we would love to all have (it does not need to be an H-Bridge) is a simple circuit that could make true square wave AC from a DC source of 10 to 1000 vdc (if possible) capable of frequencies of 3Hz to 3Mhz (if possible or even higher) that one could adjust the duty cycle from 50% to 1%

If you can come up with something that can do all this, then you are our Hero

Please note that we don't need amps it is mainly voltage we need to have available.

Hope that helps you to understand our wishes

Let me know if you have any questions.

Thanks for your help

Luc

[poynt99]

I can give it a try Luc. I can't promise anything though.

Can you post Groundloop's circuit? I'm also wondering why a H-bridge was used, or even for that matter a half-bridge?

I would think that if all you want to do is "ring the coil's bell" to build up the coil voltage using it resonant frequency, that you would just need to pulse it similar to how you are now with your simple coil in the "recirc bemf" thread. Remove the flyback diode of course.

What am I missing?

.99

[gotoluc]

I can give it a try Luc. I can't promise anything though.

Can you post Groundloop's circuit? I'm also wondering why a H-bridge was used, or even for that matter a half-bridge?

I would think that if all you want to do is "ring the coil's bell" to build up the coil voltage using it resonant frequency, that you would just need to pulse it similar to how you are now with your simple coil in the "recirc bemf" thread. Remove the flyback diode of course.

What am I missing?

.99

Hi .99,

Attached is the H-Bridge circuit Groundloop first designed.

As I said, if you know of a way to make square wave AC other then an H-Bridge we are all ears

Of the 2 years I've been pulsing coils I have never been able to bring a coil into Resonance using chopped DC. However as soon as I used true AC (polarity flip at each pulse) it all started resonating. At first I used sine wave in Parallel LC's but I never could get it to resonate using square wave however when I started experimenting with Series LC I found they work with Square waved and to me seem to be a better direction to go since we could create a circuit to make square wave.

Here is a video Tutorial of a Parallel LC but if you go to just before 8 minutes I will show that it does not resonate if you use square wave: YouTube - Coil Resonance Tutorial 3

Feel free to look at the resonance videos: YouTube - gotoluc's Channel

Thanks

Luc

[gotoluc]

Hi .99

of all my video's this one demonstrates well why Resonance is interesting.

With a 6.5v RMS input the coil reaches 110v RMS at Resonance: YouTube - Coil Resonance Tutorial 1

Neon and Fluorescent bulbs light up without any wires connected when brought close to a resonating coil. These king of things don't happen when you pulse a coil with just on off DC so I guess that is what puts Resonance in a category of its own.

Luc

[poynt99]

Hi Luc,

Yes of course I have seen ALL your videos, and watched them all several times each

You have a lot to offer all that want to learn about this kind of thing, including myself.

Can you give me an example of a coil that you would use for your resonance testing? Your speaker wire coil from your videos?

I would like to know the inductance and resistance values of it.

Thanks for the circuit. I like when folks design with the KISS principle first.

I will look into this Luc and try to come up with a method and circuit that is both simple and effective in getting a coil into the highest possible resonant rise using a DC source as you requested.

.99

[gotoluc]

Hi Luc,

Can you give me an example of a coil that you would use for your resonance testing? Your speaker wire coil from your videos?

I would like to know the inductance and resistance values of it.

Thanks for the circuit. I like when folks design with the KISS principle first.

.99

Hi .99

humm ... any coil will resonate and that was the reason I used the speaker wire to demonstrate that you don't need a special coil as even a roll of clear lamp wire (speaker wire) will resonate.

What I have found from my tests (mostly square wave input in Series LC's) is the length of wire will determine the resonating frequency. A short length will need a high frequency for it to Resonate and a long lengths will Resonate at lower frequencies. The capacitor in a Series LC is small, 200pF or less but the ideal value changes with frequency also. High Frequencies will need smaller values then the lower frequencies. Resistance of a coil is not something I have experimented much with but I think the less resistance may have a benefit but I would have to test this to confirm. I have since acquired a 5 pound spool of #10 AWG magnet wire and I could test it to a finer gauge wire of the same inductance value and compare the results of each to see how much resistance affect the performance.

I'm a big fan of the KISS principal. That is one of the reasons why Groundloop made an illustrative style circuit that most anyone with basic knowledge could understand and build for themselves. I am hopeful that you will also keep it in this style

I hope the above explains enough as to why I feel the coil values should not really affect the circuit.

Let me know if this works with you.

Thanks for all your time.

Luc

[poynt99]

Looking for an example I can test with.

Hi Luc.

I was hoping you could use your meter to test your coil of speaker wire for me. I want to do some testing in PSpice with something that is in the ballpark of the type of coils you guys might be using. It will also come in handy later so we can compare notes. If you could measure the coil's inductance and resistance I would appreciate it, and so will you later on I think.

Any coil will resonate, you bet.

Are you familiar with the relationship of inductance to the no. of coil turns?

The length difference you noticed is most likely related to the number of turns achieved in the coil. Most of the time, with a longer length of wire, you will end up with more turns in your coil. More turns results in more inductance, which in turn results in lower Fres.

Resistance of the coil won't change the Fres, but it will affect how "tight" the tuning is of Fres. A higher resistance will make the tuning to Fres quite easy because it will have a broad gentle range in the area of Fres. A lower coil resistance will give you a much narrower range where Fres appears, but the resonant voltage will also be much higher than the case where the coil resistance was higher. The series coil resistance affects what is called "Q" of the resonant LRC tank. High Q gives higher voltages and tighter tuning, Low Q is the opposite.

I await your values. I'll try to create a diagram with similar symbols that Groundloop used, although I don't favour them too much LOL.

Again, coil values won't really affect the circuit, I just want a starting point I can use for simulation.

.99