Richard VIALLE's new theory about negative mass and overunity

[tim123]

I've combined 2 lots of 5, 47 Ohm, 1/4w resistors, to make 9.5 Ohms, 1.25w resistors - for the gate driver. I feel much happier now - though they do still get hot at higher volts.

And some more results:
- I've found a new resonance at 7.3MHz - which lights the bulb more brightly, for less power...
- and a few others too - here's a list:
(apologies for the subjective bulb-brightness-units )

  Frequency         Bulb Brightness            Power Supply
-----------------  ---------------------------  -----------------------
- 1.5 MHz          Weak
- 1.8 MHz          Less Weak
- 2.45 MHz        Strong                           0.61a at 46v
- 3.7 MHz          Stronger                        0.49a at 46v
- 7.3 MHz          Strongest                      0.42a at 46v

Another note:
- The ferrite rod-cores make no difference at all to the operation of the device...!
- I've tried them in and out at the resonance points, and the performance is the same, and the tuning is the same too.


Tim

[tim123]

Another quick update... I added a variable tuning capacitor across the coil - and found that it increases the bulb's brightness (when tuned), and reduces the power draw too. (As suggested...)

The same value capacitance works for both the 3.7 and the 7.3 MHz resonances.

The capacitance required for my coil is about 145pF.

[verpies]

1) I'm able to light a small incandescent bulb from the 2 copper tubes in the coil. Picture attached of the setup.

Can you estimate the inductance of bulb's coiled filament?

- It is a sharp resonance being much dimmer at 3.6 or 3.8MHz, an the lamp doesn't light at all past about 3.5/3.9Mhz...

...does the MOSFET produce a strong signal above  3.5/3.9MHz ?

2) Power into the transistor is about 60V, and 0.37A (about 22w)

DC ?

3) The gate-driver setup has a sweet spot at about 5.7v.
...
- Above 5.7v the load current reduces, and the lamp dims, up to about 7v where it reaches it's former brightness again.

That's strange

5) I think my gate driver needs power resistors - the 1/4w ones can't take the current with the full 15v available. They get very hot at 9v.

Yes, they can heat up at high gate currents and high duty cycles.  I think you're running at 50% DUC.

They're currently at 10 Ohms, I'm tempted to try 5 Ohms to see if I can improve the gate signal.

Remember that the UCC driver can be damaged by momentary source currents above 4A and momentary sing current above 8A. So if you are supplying it with 12V then the lower resistance limit for the source resistor is 12V / 4A = 3Ω and for the sink resistor is 12V/8A = 1.5Ω.
You should also try asymmetrical source/sink gate resistors to obtain a symmetrical gate signal.  That's why the UCC driver has separate source and sing outputs.  Adjust those resistors so the gate voltage falls at the same rate as it rises.  Right now the gate waveform rises faster than it falls.

The UCC211 can handle 0.3a continuous at 18v according to the specs - so a pair of 5 watt resistors maybe?

...but the driver is supplying current to the gate only momentarily (not continuously).  The UCC can handle sourcing 4A and sinking 8A momentarily, without a problem if it is supplied and bypassed with a capacitor closely.

Maybe I'll just put a load of 1/4w ones together so I don't have to worry about them burning out...

That's safer than one big 5W resistor because you can accidentally buy a a wire wound 5W resistor that will not work at all as a gate resistor, because of its inductive nature.
When you connect bunch of smaller resistors, make a tight bundle and keep the leads as short as possible.  Remember that the thinner and longer a wire is, the more inductance it has.

The exact formula for the inductance of a straight wire is:  L=0.002*Length*[ ln(4*Length/Diameter) - ¾]
, where length and diameter are expressed in centimeters and the inductance in μH.

6) In order to measure the input & output HF power, I'd like to build something like Verpies HF wattmeter...
I suppose an off-the-shelf SWR meter would be good enough to make relative measurements though...

My wattmeter is still a work in progress. The ADL5391B multiplier for 1GHz is hard to get and the ADL5391A is for 2 GHz, but it is unbuffered so probably high impedance GHz buffers need to be added to its inputs do deal with input offsets.
The off-the-shelf SWR meter should be rated down to 1MHz for your purposes.  They often have a much higher lower frequency limit than that.  So watch out for the upper and lower frequency limits.

[tim123]

One more update:
- I can confirm that removing the bulb causes the power drawn to go up. In other words, adding the load causes the input power to drop.
- I've tried it with a range of resistances, a rough example:
  - Open circuit 0.5a
  - Short circuit 0.7a
  - 1 Ohm load - 0.4a

---------------------------------------

Hi Verpies,
  inductance reduces the output - I tried a series variable inductor, and it just reduced the output. I tried a 10w LED bulb instead, and that was good... I could measure the bulb...?

The MOSFET's good over 10 MHz it seems. The big resistance of the 60w bulb was killing the circuit before. I tried my coil instead - and it worked a lot better.

All my power measurements are DC.

The gate-driver sweet spot has gone away... Not sure why.

I did make a better pair of resistors. I understand what you're saying about making the 2 values different to improve the waveform... Maybe tomorrow...


Tim

[tim123]

Further tuning.

- The 145pF capacitance in parallel with the coil is still good.
- I've tried adding small amounts of inductance & or capacitance in series or parallel with the bulb, and have only seen the bulb dim.
- I've tried connecting the GND to one or other of the bars - and that gives a small increase in brightness - when connected to either bar.

What's going on...?

Capacitive vs. magnetic coupling...

There are 2 reasons why it looks like the effect is due to capacitive coupling:
1) The addition of the ferrite cores makes no difference
2) Placing my hand on the coil makes the bulb go out. If it was magnetic - I don't see how this could happen.

Relative Power Usage

- The test bulb with 12v DC uses 0.4a, and makes about 40,000 Lux (as tested with a luxmeter at zero distance)
- If powered by the circuit - the bulb needs about 45v and 0.3a to reach the same brightness. (Ignoring the gate driver)

Questions

- If it is capacitive coupling, I don't understand why it has particular resonance points. I suppose caps do have their own resonances...
- I don't really get why the 2 bars inside the coil would be oppositely polarised.

Next Steps

- I have a ZVS driver with a bad mosfet that I need to fix. Maybe tomorrow.
- I want to try running the coil with the ZVS driver - it's likely much more efficient.
- In order to do that - I also have to add another layer of winding to the coil - so there will be two. I know that's not typical for the device, but hey...
- I might actually just do a new coil, with fat wire - as the ZVS driver prefers lower inductances, and fewer turns.