Mosfet Heating Circuits

[b4FreeEnergy]

Hi Harvey,

If I read between the lines here do you in fact mean that there is nothing to discover here and we’re wasting our time? It’s all based on interpretation and measurement errors? Measurements on those signals are indeed difficult; too bad we don’t have an easier test which involves less complicated measurements.

So your setup is really in your cellar and you don’t look back anymore?

Cheers,
Bart

[Harvey]

Back to Basics

After wasting most of the day yesterday dealing with timing errors in my Spice simulator and getting no where I decided to take a break from it today and catch up on some reading etc.

I see that there are still some experimenting with the RA circuit and the questions regarding energy gains persist. The test of choice used to demonstrate energy gains was Test #13 (data here) [thanks to Rapid Share we have lost our Forum images for display] but I have uploaded the table of interest to my forum gallery for linking:

Click Here For Full Image

Looking at the Temps we see that the resistor temp ranges from 130°F to 140°F. Now we see the average of those 11 readings as 137.55°F and the mode is split between 137°F and 138°F.

Looking at the resistor DC baseline

we see this corresponds to ~7.1V @ 0.73A or 5.183W on average. Notice that the voltage divided by the amperage is less than 10 ohms at that temperature and is really about 9.73 Ohms.

Looking at the gate pulses of Test 13, we find that the circuit adopts a duty cycle of about 50%, but what is it really? Let's look at the data:
Click Here For Larger Image

So we see the on period of our MOSFET is really a bit more, 57.32%.

Now for how this all ties together:
We are comparing small whole apples to big sliced apples (or even oranges for that matter). In other words, we have 7.1V @ 0.73A 100% (small whole apple) and we want to know how that relates to 24.77V @ ???A 57.32% of the time. Now we need a leap of faith - we must believe that the resistance is the same in both cases, 9.73 Ohms - it may or may not be, but let's plug it in and find our current. 24.77V / 9.73 Ohms = 2.55A but wait, we have more resistance to add. The MOSFET is 2 ohms when on and the CSR is 0.25 Ohms - So the current is really 24.77V / (9.73 + 2 + 0.25) = 2.07A. But that is only 57.32% of the time. So the power is 2.07A² * 9.73 Ohms = 41.69W times 0.5732 (for the duty cycle) and we get 23.90W aperiodic operation.

That is just a basic analysis - how could it be that we are getting such a low heat if we are consuming such great power? Something isn't right. Clearly, a DC analysis simply fails to give the correct answer.

Remember the leap of faith? Did that set off any RED ALARMS? It should, because that is where the analysis breaks down. The resistor is more than a resistor, it is also an inductor and it has impedance relative to the frequency of operation. So it's true resistance to current flow is greater, and our current will be less accordingly.

Here are some questions to answer regarding Test #13:

What is the frequency?

What is the impedance of the load resistor?

What is the real power being dissipated?

How does a square wave affect the impedance of an inductor?

If the resistor was non-inductive, would the frequency make any difference as long as the duty cycle remained constant?

A DC treatment of the data obtained led us to believe that we were only using 1.3W and that the power dissipated was equivalent to that of 5.18W - does this seem reasonable? That is a gain of 398%. Clearly we need to identify how we get from 23.90W to 1.3W and we need to understand how we keep the heat. Clue: Perhaps there is AC power in the system

[Joit]

Thanks Harvey,
that the nect on my to-buy List, variable Capacitors

[Harvey]

Hi Joit,

They are the same, so the inversion is in place for them all, but I did find some schematics with errors regarding this - but in practice, they do work the same.

However, some are much faster, like the TLC version and some are lower power. So they have other properties that make them function different for certain applications - but the timing structure is always the same based on thirds. So they are very stable timing over a wide range of voltages - this is the most attractive feature of the 555 design.

To get a stable duty cycle with variant frequency only requires one thing - a variable capacitor. Use your charge, discharge resistors to set the duty cycle and vary the cap for frequency.

You will note that many engineers have added the diodes to give better control by splitting the charge and discharge sections. This is because typical applications use the same resistor to charge and discharge through and this is added in series with another on the charging which hampers easy adjustment of the duty cycle. So adding the diodes solves that problem allowing each side to function independently.

You may notice that the 'Proposed Changes' schematic that I provided, keeps the discharge clamp - this ensures that the device truly completes the discharge cycle prior to recharging. However, it should be carefully observed that too little resistance on the charge circuit can allow the discharge transistor to drop the supply voltage and cause a reset condition. (something Aaron designed purposely by adding resistance to his negative dominant circuit supply line).

The 555 is a very versatile chip with many variants - but a good understanding of how it works is critical in getting the desired results.

[Joit]

Hi,
I am looking for a 555 Circuit too right now. Something, what can increase frequency, but stay stable with the Duty cycle.

A online Lession showed a simple Principle from the Timer.
LM555. Scroll down a bit for the Block Diagram.
When V-source is ie. 8 Volt, the Voltage is internal divided with the 3 Resistor to 6-4-2 Volts.
Comparator 1 + 2 are at the pickup from 6 and 4 Volt from the Capacitor,
Pin 6 (Comp1) turns at 6 Volt Pin3 (Output) to high,
Pin 2 (comp2) at 4 Volt Pin3 to low.
BUT! the NE555 timer has an inverted Amplifier at the output,
what makes the (greater as)>2/3 Vcc at Pin6 to low on Pin3 (Output), but high before the Inverter,
that discharge the Cap over Pin7, when triggering the Base of the Transistor (Pin7)
Inputs of 555/556
The Cap discarge over Pin7 and the Resistor(2) until ~3V, then, Pin2 close the Transistor at <1/3 Vcc and Pin7 with low Output,
but the Inverter turns the Output (Pin3) High, and the cycle starts again.
The upper Resistor is there to dont make a short at the Discharge.

Here you see again the Transistor at Pin7,
and that what he labeled as Output Stage is the Inverter.
Its an inverting Amplifier, and i dont know, if the LM555 has it, but the NE555 do.
In this timer Circuit what is used, the Cap is better buffered and adjustable, more or less good.

[Harvey]

Harvey,

Thanks for this extra information. I guess this should be enough variations and info now to have my setup 'oscillating'. I will give it another try during the weekend.
I got a list of tips from Glen as well and something from Rosemary. If I shake all this together it simply has to work.

If it still doesn't work I will eat my shoes ...

Cheers,
B

Hi Bart,

I was going over some of the old stuff and ran across these two videos from August of 2009 - you may find something useful in there for getting the 555 to retrigger:
YouTube - RA Gate Oscillations Part One
YouTube - RA Gate Oscillations Part Two


Cheers!

[b4FreeEnergy]

555 info and other tips

Harvey,

Thanks for this extra information. I guess this should be enough variations and info now to have my setup 'oscillating'. I will give it another try during the weekend.
I got a list of tips from Glen as well and something from Rosemary. If I shake all this together it simply has to work.

If it still doesn't work I will eat my shoes ...

Cheers,
B

[Harvey]

Here are some early posts I made discussing the 555 timer circuit -


This post to Aaron was discussing the original Quantum (Buckley) Circuit:

http://www.energeticforum.com/renewable-energy/4314-cop-17-heater-rosemary-ainslie-63.html#post64119

Here was my first post regarding the proposed changes to prevent the overheating:

http://www.energeticforum.com/renewable-energy/4314-cop-17-heater-rosemary-ainslie-64.html#post64217

This Post contain a link to the previous post:

http://www.energeticforum.com/renewable-energy/4314-cop-17-heater-rosemary-ainslie-68.html#post64644

This is Aaron's acknowledgment of the proposed changes:

http://www.energeticforum.com/renewable-energy/4314-cop-17-heater-rosemary-ainslie-68.html#post64647

This post was a reminder that a solution to reducing that heating was provided earlier:

http://www.energeticforum.com/renewable-energy/4314-cop-17-heater-rosemary-ainslie-74.html#post66122

It really isn't a big deal - but its a simple modification that removes one component, gives better adjustment and stops the discharge heating.

Cheers!

[b4FreeEnergy]

Few questions from the field

Hi there, I did post this on Rosemary's thread as well but just in case not both threads are read by everybody, I'll post it again here.

A little question about the 555 timer circuit. I’m trying to have that special ‘oscillation’ reproduced on my setup and while measuring I noticed that the 110R resistor gets rather hot. Is this intentional? Is there a special reason for having a rather high current through the setup circuits for the 555?

If you put the 2K pot-meter to zero Ohms for minimum on-time while having the 10K pot-meter to maximum resistance for maximum off-time it’s normal for that 110 Ohms resistor to get hot. Pin 7 of the 555 is pulled low by an internal transistor if its output is high. This way the current through the 110R is 109mA. The dissipation will be close to 1.3W (The duty-cycle not taken into account, on average it’s a little less in fact)

Anyway the struggle continues, any remarks and or tips are welcome.

Best regards,
B

[ashtweth]

Guys thanks so much for all this, all is in your PDF and will be up ASAP Finished our rep to send in for a good scope just about to send Harvey and Glen the snaps of the device, hope to get some measurements and publish back up results to support Harvey and Glen.

Ash

[b4FreeEnergy]

Hi Fuzzy what type of tape he used to that glass cylinder?
Thanks

@Guruji

This is not even Teflon, it is ordinary tape. I used it to keep things in place because I did not have anything better at hand for the moment. The plan was to use that same silicone rubber Glen used but I don’t have it yet.

Cheers,
B

[Harvey]

Hi Harvey interesting that you've posted regarding the gauge. Did anyone try modifications on the circuit for a bigger resistance heater?
Thanks

This information was brought to the attention of those involved early on but it was not accepted well by a specific person because it goes in the opposite direction of the predictions.

I am currently testing a 7AWG low resistance 14µh coil to test for energy gains. According to the 'predictions' this big fat wire should dump copious amounts of energy into the system from the superluminous magnetic field, especially since none of the energy will be wasted thermally.

Here's hoping

Click Here For Larger Image

[Guruji]

Heater

Hi Harvey interesting that you've posted regarding the gauge. Did anyone try modifications on the circuit for a bigger resistance heater?
Thanks

[Harvey]

Hi Everyone,

Today I wanted to analyze the Nichrome Power / Temperature curves to see what wire size really gives the best thermal profile against the power required to produce that temperature. We already knew that the smaller wire was able to produce vastly hotter outputs for much less current, but because the resistance of the wire goes up with the smaller gauge wire, it demands more voltage to push the current through that higher resistance.

But the question was, how much voltage, or more importantly, how much power?

Fortunately, we do have a table for the temperature for N series resistance wire:
Nichrome N8 Amperage / Temperature Table

And, that same site also gives us a resistance per length table for the same wire. If we know the amps and the resistance we can calculate the power easily with the I²R formula.

Here is the Chart I produced for AWG wire sizes 11 through 40:

Click Here For Larger Image

You can see that AWG 11 requires much more power (281.21 Watts) than AWG 40 (8.52 Watts) to produce the same temperature of 2000°F.

The resistance values are per foot and so this graph represents a single linear foot of each of those gauge wires. Also, it should be noted that the empirical data used to produce these charts was taken on tight coiled heating wires sprung to exactly twice the tight wound length. The arbor Diameter (rod Diameter used to wind the wire on) ranged from 1/32" for the smallest wires, 1/6" for the small wires, 1/8" for the medium wires and 3/16" for the larger wires. These shapes and sizes do play a small factor in the heat dissipation characteristics and were probably chosen to optimize the effect.

Attached is the Excel Spreadsheet that I used to produce the chart with the tables included.

IMPORTANT: You must save the file and remove the ".doc" from the end of it in order to view it in Excel. This is NOT a word document, but that is the only way I could attach it easily.
EDIT: If you use FIREFOX you can select to open it and choose 'other' then choose Excel =)

Cheers !

[Harvey]

That looks like Telflon Plumbing tape but I could be mistaken. If it is, I doubt that it will work well as a heater above 327°C. This material is known as PTFE (polytetrafluoroethylene) and has a melting point of 327°C.

But if all you are doing is replicating Glen's tests - then is should be ok as most of his stuff is well below that temperature.