Goeytex

Has anyone here ever tried putting a sonic or ultrasonic piezo transducer in a water cell ?   

The ultra sonic transducers designed for cleaning parts go for about  $35 each.   It may not help make gas,  but the tubes
would  probably stay nice and shiny ...

I'm not arguing, I'm proving...but, believe w/e you want.
Fact of the mater is....I know how piezos work....and a porous material would be a poor piezo indeed. As for my mind...you have no idea!
You are spreading unsubstantiated claims...I would encourage YOU to read it thoroughly
Good day sir....I said GOOD DAY!


P.S.

One more piece of logic to prove it....
(http://i175.photobucket.com/albums/w152/Jdub6d9/Untitled-1-3.jpg)

Notice how the "vitreous ceramic" makes a seal between the outer steel housing and the inner nickel lined tube???(like the porcelain in a spark plug...ehhh?..ehh?)....well, a piezo expands and contracts...if that ceramic were piezo...it would break apart!!

Score 1more for logic

I have to agree with Radiant here.  To suggest  the ceramic  in Puharich's device is piezoceramic,  is purely speculative and a leap in logic in my opinion.  In the available online lectures as well as the patents ,  Puharich states the  ceramic is vitreous and porous which  would pretty much rule out  piezo.     If it were piezoceramic,  as the term is commonly understood, any legitimate researcher/inventor  would have said so in their patent.   Puharich never mentioned it anywhere. Neither did Meyer.   

Hi Gauss,

Well, test 1 is done.
I used an outertube of 15 cm /  6 inches long
Innertube  is like 18cm /  7 inches.

I have to say that NO vibration what so ever is noticed.....I tried destilled. I tried tap and yes, even some with NOAH.

I have the most soft spacers in the world......
I used a HP signal generator with a 50% duty. I can run this thing between zero and 50Mhz.
Hooked it up to a FET and a variable powersupply which can run from zero till 35V. Max 3 amps.

So, again. No vibration detected.

Question: Have you tried shorter type tubes? Or does it only work with the length you have tested?
Question: At what kind a frequency are the tubes vibrating?

Steve

Let's not  forget to take into account the size and shape of the entire water cavity.  
It is possible that this is also coming into play here  and not just the tubes.

To measure the frequency of the vibrations  you can download any of the many freeware and shareware spectrum analyzer programs and use a mic
attached yo your PC sound  card.  Most of the programs  will display a real time Fast Fourrier Transform (FFT).  And give you a frequency within a few Hz.

http://www.hitsquad.com/smm/win95/SPECTRUM_ANALYZERS/

Positive side pulsing.

Fig 8B patent 5149407 shows pulsing positive in 2 places.

Figure 8B of  5149407 shows a bipolar transistor used as a  "high side switch".    Both switches are high side switches in this
drawing.  Same thing in 4798661.   Meyer uses low side switching other circuits.   I could be wrong,  but I'm not  not sure that the load cares too much  as to which side is switched.   Each causes current  to flow when closed and current to stop when open.  Spice models show no difference in the  final waveforms using either technique.   However there may be some advantages in using a high side switch.  But that is probably something for discussion in another thread. 

In any case,   the PWM  output  of a microprocessor  based system can turn on or off a high side bipolar transistor  just as well as it can  a low side FET. 
 

  I think your basing your data on old Meyer patents.
Newer stuff shows positive pulsing.

The patents you referred to were applied for in  1985 and 1989 and show high side switching for their respective  applications.  These were block diagrams and not actual circuits

WO9207861 applied for  1990 (Later)   shows  low side switching  in figure  5  for a particular application.  In this patent  the low side switch is shown in a more detailed ans specific circuit.   Yet in Figure 10 of the same patent he shows a boiler plate VIC using a high side switching.

My take is that the date of the patent is irrelevant. Newer does not necessarily mean better.   The boiler plate VIC drawings are  meant to show  that the coil is pulsed and not necessarily that it must be with a high side switch.   Again,  I  don't think the transformer primary cares with side the switch is on.  It only cares when and how often the current is allowed to flow.   
 
Goey

Geoytex, I have one suggestion if you build such a nice PWM micro controlled.

We are not seeing any positive side pulsing.
Will this work on the positive line?
Work that into the outputs.
I know you don't care for the positive side, but thats more control. More variables!

You can do it.

Did Meyer pulse the positive side?  I don't  think so.    I went over the WO patent  schematic in detail and saw where the positive side voltage amplitude was controlled by a feedback circuit ,  but that was not actual  pulsing  of the positive side.  It was more like a voltage regulator that adjusted voltage based upon engine demand  and/or gas pressure.
 
Now if there is evidence based  upon someones research and experimentation  that positive side pulsing is beneficial,  I would certainly be interested in seeing  that data.   Certainly the positive side "could" be pulsed ... kind of like a synchronous buck cell.  Not a problem for a micro based system.  The timing would just have to be correct.

Edit:  Let me clarify a bit.  I recently had a discussion with a nice gentleman working on this stuff and he was of the opinion that the circuit in the WO patent was pulsing both the high and low sides simultaneously.  I went over the circuit with him component by component to show that it was not.  Only the low side was actually switched.    This is what I initially thought you were referring to... simultaneous switching of both sides.    I see that it is not what you meant .   

 

Mr. Dankie,

I think you may be suffering from unjustified paranoia.    Take a deep breath and relax.

As I said in another post,  I will only consider building something like this  to sell if there is enough interest.
I am building the prototype for my own use in research and experimentation.   If it works out that someone wants and can
afford a system like this,  then I will consider building a few more.     Otherwise I will keep it to myself and  possibly share
the design  in the  Public Domain.  

If I truly wanted to compete with you I would  design a simple manual  dual output PWM board around a  79 cent 8 bit microprocessor,
program it to do whatever yours does (and more),  have it assembled in China,   and  then and sell it for $79 (and actually make money) . But that is not what I am after.   I have little interest in the money.  

But be assured that I am not going to stop what I am doing because you are afraid it my cost you some sales.  What I am doing is not
going to hurt your sales.  

So relax .  You have  nothing to be afraid of  here.  

Lol

This person is copying everything I do . Dont you have a job that pays good money already ?

I have it all built already , you can do WHATEVER YOU EVER WANTED TO DO  , updating my pcb now , Im waiting for my friends video cam .

Tomorro or after that , theres these holidays here now .

Oh really ?    

 I can assure you that I have not even looked at anything you have posted in regards to circuits.  But now that I have looked,  I don't see where you have ever posted an original circuit.....   Have you ?      

What microprocessor are you using?   How many ADC's ? Are the PWM's internal to the processor or are you generating them with interrupt routines?   What clock speed does your processor run.   If  you come up with a firmware upgrade to improve functionality  or add features will you do a processor chip exchange ?

 Let's see some drawings or photos of the user interface and display.  Is yours a graphic or character display?   Does your system have a built in self-test  and diagnostics routine ? 
 
Certainly,  if you have already perfected the ultimate Microprocessor VIC Controller that  cannot  possibly be improved,  then the  rest of us should just stop what we are doing and wait for you.    

Heck,  I'm  thinking about  killing myself now.   All this  wasted effort you know ......

Sorry  folks,    all plans are canceled!     I'm getting a rope !    

Steve, 

Do you have any values for the  choke, capacitors, and resistor ?

What is the frequency at the transformer input ?   60 Hz ? 

Anyone with electronic experience can follow that and fill in the blanks, even point out some flaws I may have overlooked in this setup.

I have 30 years electronics experience and I cant follow it too easily. 

Are the caps in series or parallel to the coils ? 

How about a sketch of the schematic ?   A picture is worth more than a thousand words.

Goey

Goey
 
Steam.... It was not steam...lol.. and yes, it was AC, but i had to have a adjust the plate gap ( bigger gap than with DC ) so the overload protection in the inverter didn't start to beep and shut itself down. AC can indeed make HHO.
 
I am thinking of getting me a 1000W inverter... really blow the water out of the bucket

Now .....tell me that the water did not get hot ......?   

Did you take and record temperature measurements, current readings and voltage readings across the plates?   

So ... why does my  Vicks Vaporizer make steam instead of gas?  All it is is 2 round carbon looking electrodes separated by a an inch or so with  120 Vac applied.   Current can be up to 6 amps or more depending upon the mineral content of the water.  Just boils the water. 

Is there something you are not telling us?   

Andrija Puharich used AC to make gas.  But he used Amplitude Modulation,  a special ceramic coating on the center electrode and a glass insulator between the electrodes.

Goey

An alternator produces a sine wave .

A sine wave is much smoother than pulsed dc , on the scope I can see that this rhytmic motion will do better than pulsed dc . It just makes sense that it would .

You are correct Dankie.  By definition an "alternator" is an electric generator  that produces alternating current... ie. a sine wave.    But an "alternator based system"  can produce other wave forms as a result of adding other components. 

"Resonance" is always in the form of a sine wave. So it could make  sense in certain applications to use a sine wave input .  Make a simple series LC resonant circuit and hit it with a sine wave at the resonant frequency and with a with a square wave at the resonant frequency. The sine wave will give greater gains given the same power input.   But .... square waves are easier to generate over a wide frequency range.   

 

I have a 300W pure sine wave inverter and with the right plate spacing the gas output is extreme.

Have read that inverters can today have a efficiency up to 95% comparing the input and output.. but the energy in the HHO gas produced is at the moment unknown for me... Didn't Master Steve use a inverter for that motorbike idling?...Hmmm   

So,   are saying that applying a 120V AC   @ 2.5amps to a set of plates makes an extreme amount  of gas?   Are you sure that isn't steam?      Maybe you rectified it to DC first?

Please tell more.

Master Steve used 2 VIC's with blocking diodes and resonating chokes in where he got LC resonance and he busted water with 40Kv and 1mA, producing a massive 100ltres per second.

But i just forgot how to replicate it..

Steve

Steve, when you remember.... I have a check for you for $50,000US for further development.

That's a sad thing. 
as always, it seems many people do have some good results but no other can replicate it because there are no good documents. and if there are good documents (like ravi) it does not work.

You said a lot there Haithar.

You  have to consider that SOME of those claiming to have good results may just be blowing smoke or seeking their 20 minutes of fame on Youtube.  (documents or not).  Some may not be.  But many times it's hard to tell which.   

Also consider that,  many experimenters have no formal education or training  in how to do systematic and methodical  testing, note taking, etc.  It's same with technical writing skills (documentation).  Some have difficulty explaining  what they've done in terms that others can understand.   

Then there are the "mean people" . These kind might have some knowledge,  but alienate others due to their pissy & arrogant attitudes.  These can't have an intelligent exchange of ideas with out ad hominem attack.  eg.  "If you  cant see what I'm saying (and agree with it) then,  you are an sub-moronic fool  and  have nothing to offer anyone ! " 

Yeah Steve.  Mean people do suck. 

i'm intrigued by warps post but i never read something about 3500rpm, an alternator or that FQA30N40. It's probably because i did not read every post of every account he is using word for word, but if you could make like a document where you collect your knowledge, in a way that the others from this forum can understand and then replicate (i'm sure there would be enough people to try it), we could all get this working together. communication is really the problem, everyone is doing his own stuff, there is so much false information, and everyone would have to figure it out for himself, not to say most of the people at the waterfuelcell.org forum for example don't have any clue about electronics and mess things up more.

3500 is the rpm/frequency that worked for Warp in his particular setup. The FQA30N40 is just a 400V 30 Amp  QFET from Fairchild Semiconductor . Nothing particularly magical about either one of them.  However,  If  someone wants to replicate what Warp did,  then they  will need to use exactly what he used.   If the RPM was 3500  then use 3500.  If the FET was a FQA30N40 then use that one.  If a tube was exactly 4.0 inches long by 1/2" diameter then don't use one that is 3.9 inches long by 5/8" diameter and expect it to work the same.

 
when the first step (getting more HHO energy than you put in via electricity) it's not important if you cannot run YOUR car on this immediately. there are plenty of options afterwards. (even stan ran only a lightweight dunebuggy with it)

I sometimes wonder why there is so much focus on running a car with  HHO gas.  There are other more easily engineered applications.

Goey

Hi, 

Hope this can help.

Slow moving signals like sawtooth and triangle signals can sometimes be susceptible to noise.  When using this kind of signal to trip a comparator,  the comparator can burst into unwanted oscillations. Just about any high speed comparator can do this. 

Consider that an LM 311 comparator has a built in hysteresis of about 3 millivolts. So a  difference of 3mv between the inputs will trip the comparator. Noise above 3mv on the input signals can cause oscillations at trip point. This can be very pronounced with a slow rising and falling input signal and even more so if there is high frequency noise on that signal. Cheap (Made in China?) Florescent lighting  ballasts are notorious for generating noise in the 20 kHz - 100 kHz  range. Keep them away from your circuit.   

The LM311 is very susceptible to these oscillations if certain precautions are not taken.  If pins 5 and 6 are not used,  they should be shorted together. A .1uf ceramic capacitor should be used to bypass the positive supply input and should be located as close to the chip as possible.

There should be a ground plane on the bottom of the PCB running under the LM311 circuity. The signal traces should be routed between ground traces. If a pot is being used to supply the reference voltage (as in a PWM circuit),  the leads from the pot should be as short a possible and should be tightly twisted together.

Ramp signals can be generated in many ways... 555 timers, OP Amps,Current Sources, VCO's, etc. Noise and jitter on these signals can be caused by many things but can usually be eliminated with good design and proper board/component layout techniques. Slapping components down with no regard for component placement, ground and power planes, and trace size/routing ...will likely cause problems.

Where applicable, each IC on the board should have its own .1uf ceramic bypass capacitor and it should be as close to the IC's + Supply pin as possible.  Output signal traces should be routed away from input signal traces. Right angles on traces should be avoided wherever possible (use 2 45's).     

If the board has it's own voltage regulator,  the recommendations of the manufacturer for both  input and output bypassing should be used. A good sized input capacitor should be used in any case. In the case of the LM311,  the power supply bypass capacitor should be no more than a few inches from the chip.   

When prototyping on a bread board it may be difficult to eliminate cross coupling noise completely since you can't really make ground or power panes. Keep the wires as short as possible and keep outputs away from inputs.

If there is still considerable noise on the signal going to the comparator,  you can add hysteresis with positive feedback.  In a Meyer/Boyce type pulser circuit using a ramp/comparator PWM, 100mv hysteresis can be very helpful.   Attached is schematic showing how to do this.  Positive feedback can only be added to the + input of the comparator so the circuit should probably be designed in inverting mode where the reference voltage (Pot) goes to the + input and the ramp goes to the - input.

You can also use capacitors to reduce noise. A .1 uf cap from the  + reference comparator input to ground can filter out considerable noise.   

"Jitter" is basically time based noise where frequency or duty cycle of a signal changes periodically. 555 timers are not very susceptible to jitter.  However, a VCO like the 4046 can have considerable "jitter" on the output if there is noise on the VCO input. The VCO voltage should be as clean as possible. The techniques detailed above should assure that.

Sometimes, a cheap or defective oscilloscope can show noise or jitter when there actually is none.Some signals are difficult to trigger and an external trigger input may need to be used.Where you connect the ground clip can be very important.  When measuring a signal coming off of an IC,  try to put the ground clip as close to the chip as possible.  If the ground clip is 12 inches away (like at the ground terminal of the main power supply) you may see noise or jitter that is not really there.

The first attached file is a JPG schematic of a working  circuit. that has no noise and no jitter. A 555 is used to generate the ramp,  but this could just as well be a 4046 PLL IC,  or any other   circuit that generates a triangle or sawtooth.

The second file is the Spice simulation that can be run with LTSpice.  You will need the spice models for the LM311 , the TLC555 and  the potentiometer  in order to run the simulation.  These can be downloaded from the LTSpice Yahoo Users Group. 

If you are truly interested  in running the circuit simulations that I will be posting  here,   send me a PM and I can assist you in getting the necessary models downloaded,  installed and  working properly.   

Goey 


Goey

I have been told that the "brown mug" can be prevented in a flat plate electrolysis cell by putting a porous membrane between the plates so that the  two gasses cannot combine in the water.  The holes in the membrane are small enough to let water through but not the bubbles.
Something like nylon mesh was suggested.   Of course this would not be practical in a Meyer tube type cell,  but if true might suggest what the brown stuff could be ( a byproduct of oxygen and hygrogen gasses mixing in relatively impure water loaded with all kinds of nasty crap) .   

I have heard quite a few theories as to what it the brown stuff is,   but unless these can be substantiated with a actual chemical analysis of the stuff... they remain only theories to me.   I certainly would not claim to know without a chemical analysis.   



 

Didn't mean to be condescending really.

But there seems to be quite a few people in regards to this stuff  that are dead sure that they have the answer,
yet they really only  have an untested theory or idea.  And in light of the fact that they have not  proven their  theory
in practice,   they preach it  like it is the irrefutable gospel truth,  while  wondering  why others don't
jump on their bandwagon and become glassy -eyed converts.

But I am sure that you are not one of these people.    Are you ?

Too many people have declared they have the answers to this stuff prior to ever having done squat .  They are sure they
on on the right path and anyone on a different path is missing it.     So you should understand that those us of that have
built multiple systems and spent countless hours and blown dozens of FET's  on this stuff  trying almost  every conceivable way
of replicating Meyers process .....might be a bit skeptical of untested theories.

As far as comments go,  I will comment whenever  I see fit,  especially on a thread that I started.  And I will
try not to be condescending to anyone.  

Again,  my comment was not intended to be condescending,  but rather to make a  point. 

I wish you great success in your endeavor.

I don't know what I need to do to get people to see the connection!!!!

Maybe build a working system ?   

What microcontroller are you using, the pic?

Good question.   

I have not selected the micro yet.   It be be selected based upon how many I/O's and  ADC's
we will need  need,   and how well the micro can handle the multiple PWM outputs at 40 - 50Khz. 
Also I want to select a micro that  that has room for expansion (extra I/Os,  ADC's, comparators, etc
 so I don't have  to spin a new board  when something is changed or upgraded.   Ideally we will design
it so that one basic board can be used for several different applications depending upon the code and
user interface.   

I have development systems for PIC  Atmel,  and ST.  So it will be one of these. 

A way to control the voltage by external input, for example, if one of us ever put this thing in a car, it would be nice to be able to vary the voltage with the gas pedal, so you would need an input to your circuit for external control of the input voltage and/or the duty cycle and/or gating... since each can control gas production, depending on the set up. You can't really play with the dials when you are trying to drive. This might be complicated or beyond the scope of this device, but I'm just throwing it out there

This will be for Lab/Experimentation purposes and not intended  to control a cell in a moving vehicle.   A  System designed for a
vehicle will be much different and would also need to include  oxygen sensor compensation.    Let's lean how make gas in a lab using the Meyer process before we start launching rocket ships to the moon ( or Porches down the Autobahn.)  

If you have a sweeper and pll, then there is no use for a frequency dial, but i guess you would want dials to play with gating, duty, and input voltage from 0-12 volts.  

I have found manual control to be quite useful for:  

1. Directly pulsing a cell with no transformer.  ( Collecting baseline data)
2. Testing Coil various combinations where the resonant  frequency or coil performance is unknown.
3. Most experimenters are control freaks and want to be able to do manual  adjustments (like dialing
in a specific frequency)   

It might be interesting if you could have a memory in it, (like an SD Card) that would log the action of the device for several aspects, like frequencies that resonance was found at, and then use this to find effective sweep ranges.

Add $150 minimum for the SD card Interface.  

If you wanted to get extremely fancy, for the sake of throwing out ideas, if you could come across an electronic gas flow gauge and pressure gauge, and have these as inputs to your circuit, then have the readings from these gauges matched up with the voltage/duty/gate/frequency and such, and then logged in your memory stick, for analysis.

An A/D input can be reserved for gas pressure and flow  transducers.  Industry Standard Instrumentation specs for these devices is 4 -20 ma output full range.  Drop this across a 250 ohm resistor and you have  a 1 - 5 volt input that can be fed to a multiplexed  A/D input.  We probably only need to sample  these inputs  10 times per second or maybe even less.    That would  only take  a few extra components and a few lines of code.   The  gas pressure sensor could trigger a fault condition ( too high)  or control the gating and/or  voltage  level
to the cell. 

Do you have a rough estimate on the price range of this device? And time-frame of completion?

At least  3 weeks to get a breadboard prototype up and running.   Have no clue on the cost.  It  probably won't  be cheap.  How much are
you  willing to pay ?      

It is in the works.

Tell me what you want it to do.   I have my ideas  but  I also want yours.

So far a 4 x 20 Back lit LCD Display that can display Frequency, Current, Duty Cycle and Gating.  I could go
with a graphic display,  but that adds about  $20 to the cost plus programming time.   The graphic display would
allow display of actual waveforms.

The user controls can do whatever I program them to do.   The turn knobs are rotary encoders as well
as momentary push button switches.   Pushing a knob in can toggle various modes and programming options. 

So tell me the features that you think will be most beneficial and  practical.   Don't worry I won't laugh at anyone.

Please don't ask for a USB interface  for a PC because I cannot afford the time to write a Windows App.

If there is enough interest and I can keep the cost reasonable,  I will consider building and selling a few  of these. 
Otherwise I will have the only one. 

Goeytex

Webmug,  

The mixer and driver  sections of the circuit will  work fine with your 2 microprocessor PWM inputs.
If your micro is  running at 5 volts you can use either CD4000  or 74HC series logic.  

Below is a circuit that will work for you using CD4000 Logic at 5 volts.  You will need an additional
12 regulated supply  for the FET Driver.  

NOTE:   Diagram was updated to add  Output Enable/Disable

The once heralded  Lawton Circuit ruled the boards for a while.  But as anyone who ever built or bought
one knows,  it leaves a lot to be desired.  It is unstable and barely controllable. The adjustments are too
sensitive.  Frequency changes with duty cycle and vise versa.  The gating is out of sync causing partial
pulses.  About all you can say for it,  is that it makes pulses and that with considerable tuning you might
can get the signal you want.

There have been many improved circuits based upon Lawton's use of 555 timers.  But 555 timers, as
handy as they are,  have certain limitations. Some folks have recognized these limitations and have
designed an built circuits that overcome these limitations. One is to use the 555 timer as sawtooth
generator/ oscillator, and then send this to a high speed comparator to make a classic old style PWM
generator.  This can actually work very nicely with well selected components and thoughtful design and
layout.   With the addition of some logic gates and a good FET driver,  a stable working circuit can be
designed that will work very nicely for experimenting with the Meyer VIC.

One of  the problems with the 555 timer in the standard configurations is that duty cycle and frequency
affect each other.   What we need is a sawtooth/triangle generator that is stable over the range of
frequency that we want to use. For Meyer that would  be between 100 Hz and 20K Hz.  But let's extend
it and go up to 50 kHz .  This is well within the capability of a 555.  However there are other options.
One is to use voltage controlled oscillators.  One for the main frequency and one for the gating signal. 

There are quite a few out there to chose from.  Meyer used a CD4046.  These are still available and
work very well up to about 1 mhz. The 74HC4046 is good to 10 mhz.  However this requires a 5 V
regulator.  So if we stay with 4000 series logic we can use 12V and only have 1 regulator. We need 2
VCO's.  We will also need 2 high speed comparators.  The LM311 will work nicely.  The logic gates will clean up
the signal and give about 30 ns rise and fall times to the FET Driver IC.  Pick a FET  driver IC that
operates with CMOS logic up to 16 volts.  Fairchild, National Semi, Microchip, etc all have good
Low Side FET Drivers.

The VCO  puts out a square wave and we need a triangle or sawtooth to do the comparator type
PWM.  This is not a problem.  We can take the triangle signal at the timing cap of the VCO,  buffer it
through an Op Amp and then send it to the comparator.   Adjust the gain and offset of the op amp so
that the triangle signal into the comparator goes from 3 volts to 9 volts.  Adjust the values of the
voltage divider resistors so that the control signal to the comparator goes from a little above 3 volts to a
little below 9 volts. 

Below is one circuit  variation that works very well.     Resistor and Capacitor values need to be
calculated based upon desired frequency range.  See the CD4406 Data Sheet from Texas Instruments.
The values shown will get you in the ball park. 

As you can  probably see  any 2 PWM's  can be fed into the Flip Flop/Mixer section.  They could be
made with 555's or anything else.  The flip flop syncs up the edges of the 2 PWMs assuring that there
will be no incomplete or partial pulses at either the beginning or end of the gated pulse stream output. 
The FET Driver IC assures proper gating of the MOSFET and reduced heat and stress on the FET.
A resistor  can be put in series with the gate should you want to slow down the rise and fall times.
Optionally,  an 18 v Zener diode can be put from the gate to ground to clamp the gate to source voltage
so that it never exceeds the +20V gate to source limit of most MOSFETS.

Bypass and decoupling capacitors are not shown,  but should always be used.  Each IC should have a
100nf  decoupling capacitor as close to it a possible. 

So what we have here is a stable circuit that can operate up to well over 50K Hz and down to 0 Hz  (not
recommended).  Frequency and duty cycle are independent of each other.  Gating is digitally  implemented,
eliminating the sync problems ( partial pulses) with Lawton and other circuits.   A dedicated
FET driver assures proper gating of the MOSFET.

Have fun.