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Author Topic: Tinman's coil shorting circuit  (Read 71197 times)

penno64

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Tinman's coil shorting circuit
« on: September 12, 2015, 11:18:54 PM »
Hi all,

Does anyone have suggestions regarding Brad's coil shorting circuit?

From the videos, we see the coils are feed into the circuit and on the top of vero board,
one transistor, one diode and a resistor seem to make up the coil shorting.

Total output is then feed into a larger smoothing/buffer cap.

Any diagram suggestions are welcome. I am happy to build and test.

Regards, Penno


gyulasun

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Re: Tinman's coil shorting circuit
« Reply #1 on: September 13, 2015, 01:09:01 AM »
Hi Penno,

I drew these two schematics to someone but it was in early July and then tests have been suspended, I have no further info yet.

I also noticed the diode in the veroboard and I thought it is the diode Tinman also showed in his schematic in series with the switch S1. 
If the diode on the vero board is not that one, then the diode shown on the board could be in series with the drain pin of the MOSFET to defeat the effect of the body diode but I did not show this possibility in my schematics.
I may be wrong but I assume in my schematics that the body diode of the MOSFET (shown between drain-source) has no unwanted shorting effect on the induced voltage of coil B when the MOSFET is in the off state. 
Normally for coil shorting when done with MOSFET, two seriesly connected MOSFETs are used (their source pins tied together and the two drains short the coil when both FETs are driven from the same control signal) so that their body diodes block conduction for any AC polarity.  Tinman may have not used two MOSFETs because there is only one shown (I do not assume there are hidden components under the vero board, though it occurs to me he mentioned he did not include in his schematic all the components he used).
So in case two MOSFETs were used for coil shorting, then later I can draw such schematic too.

The reason for drawing two schematics shown below was to show the polarity for the gate-source control signal is important, meaning to choose the connection version which brings a positive gate pulse with respect to the source pin from coil A.
Tinman did not probably use a potmeter to reduce the spike amplitude below 20V (I use R2 as a adjustable voltage divider with R1, this latter is between the gate-source). Tinman did mention the need for reducing the control spikes to the gate (not to burn the gate-source of the MOSFET), maybe he just used R1 in parallel with gate-source to prevent this,  not sure. Zener diode can also be used in parallel with gate-source.

Gyula
 

penno64

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Re: Tinman's coil shorting circuit
« Reply #2 on: September 13, 2015, 02:25:30 AM »
Hi Gyula,

Thanks for that.

I understood that the diode was for rectifying only.

The mosfet mentioned was the irf540

The resistor unknown.

It just seems simpler.

Regards, Penno

shylo

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Re: Tinman's coil shorting circuit
« Reply #3 on: September 13, 2015, 10:47:00 AM »
Penno64, Thanks for starting this thread.
Gyula, I thought that the little circuit board that penno64 showed was the right side of the of the circuit Brad showed in the attached diagram.
In his he has the shorting  shown as just a block.
Where do the spikes go into the cap?
I'm totally useless with electronics, I've been trying mechanical shorting but with no luck.
Can it be that simple , a diode, mosfet, and resistor?
Creating spikes is easy the hard part is catching them and storing .
Thanks artv

gyulasun

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Re: Tinman's coil shorting circuit
« Reply #4 on: September 13, 2015, 03:23:21 PM »
Hi Penno,

Yes, the diode on the vero board can be the one connected in series with switch S1 and this diode may steer the spikes into the puffer capacitor placed also onto the board.
It may be simpler but we do not know about components Tinman referred to that he has not shown.

Hi Art,

It is very possible that the right side of the circuit Brad showed in his diagram is the little circuit board Penno showed from the video but in Brad's diagram there is no MOSFET on the right side. Of course the circuit board could host the MOSFET and the wires could lead to the left side where Brad indicated the shorting circuit as a block.
On your question: The spikes can go to the puffer capacitor first by induction and then via the diode when switch S1 is on. Remember that the two stator coils share a common magnetic core and when you short and unshort coil B, the spikes appear across coil A by normal transformer induction. With closing S1, the spikes are steered into the capacitor. Also remember that the rotor is brushed and also part of the magnetic circuit so spikes from the rotor coils should also induce voltage and current in the stator coils.
On your other question whether it can be that simple, a diode, MOSFET and resistor: well, basically it could but experiments can tell this, together with knowing what components are not shown, especially in the shorting circuit block. This block may include two MOSFETs connected in series to do AC shorting where the body diodes cannot shunt any AC cycle but the controlled drain-source channels can.

Gyula

penno64

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Re: Tinman's coil shorting circuit
« Reply #5 on: September 14, 2015, 12:05:23 PM »
Trying to get some electronic schematic drawing tool to post my take on it.

penno64

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Re: Tinman's coil shorting circuit
« Reply #6 on: September 15, 2015, 12:14:26 AM »
My guess -


gyulasun

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Re: Tinman's coil shorting circuit
« Reply #7 on: September 15, 2015, 01:03:46 AM »
Hi Penno,

In your drawing the gate-source of the MOSFET is biased via the left side stator coil by the DC voltage stored in the puffer capacitor, and if I figure correctly the bias is positive for the gate so that the MOSFET is ON all the time except for any induced peak AC voltages that are able to switch it off by defeating the DC bias. But this is not neccessarily wrong, of course, I think this would also be a possible schematic. 
Did you place (insert) the switch (named as S1 by Brad) into the gate wire where you drew two red squares with the question mark?
The gate-source of the MOSFET should be protected against overvoltage (especially when there is no load across the puffer capacitor) but I think you know that.  I would not consider this drawing a simpler one than I proposed though.  8)

Gyula

penno64

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Re: Tinman's coil shorting circuit
« Reply #8 on: September 15, 2015, 11:02:14 PM »
Thanks Gyula.

Using just the components we can see -

gyulasun

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Re: Tinman's coil shorting circuit
« Reply #9 on: September 15, 2015, 11:14:10 PM »
Hi Penno,

Okay, thanks too. 

When attempting to build, you may wish to consider some further components protecting the gate-source agains overvoltage (this is why I indicated the potmeter and the resistor as simple means.  Brad mentioned the unloaded DC voltage in the puffer capacitor went up to several tens of Volts or higher (cannot recall at the moment correctly), that is too high for the MOSFET gate-source.
Do you happen to have the main components for the setup?

Gyula

Jimboot

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Re: Tinman's coil shorting circuit
« Reply #10 on: September 16, 2015, 12:41:37 AM »
This is the sort of question I wish MarkE was still around for :( If we are shorting the output are we doing it to collect the collapse? If so why is that better than just taking the AC? Is it to change the polarity of the gen coils to aid rotation?

penno64

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Re: Tinman's coil shorting circuit
« Reply #11 on: September 16, 2015, 01:03:53 PM »
Maybe Brad might like to throw us a bone

gyulasun

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Re: Tinman's coil shorting circuit
« Reply #12 on: September 17, 2015, 12:03:28 AM »
...
If we are shorting the output are we doing it to collect the collapse?
...

Hi Jimboot,

Your question was answered by Brad in June if you go back to his posts. See his reply to woopy (Reply #3782 on: June 22, 2015, 12:48:14 PM, page 253) for instance  where he explains that a shorted coil in the right moment works as an electromagnet and he bucks its field with the rotor field, this is what gives some extra torque in the first place and the collection of the collapsed field takes place also and steered to the puffer capacitor.  So Brad shorts stator coil B in the first place to get an increase in rotor torque.

Further quotes from Brad from his other posts:

So here is where im at with V3 of the rotary transformer. Adding the bucking coil setup did indeed increase the overall output of the system-both mechanical and electrical. When  i say bucking coil, i mean a coil that acts as a magnet that can be switched on and off at the right time.  As it is a coil that is being shorted,and thus becomes an electromagnet that pushes against the rotors collapsing field just at the right time. This field also travels around the stator core,and boost the field within the secondary(generating)coil that provides the power for the globe.
So we do have a coil that is bucking both against the rotor's field and also the field of the generating coil.
-----------------------
I am using a bucking field effect between the rotor and coil B,not between coil B and coil A.

Coil B's current can flow into the cap along with coil A's current for a brief period of time,but coil A's current cannot flow into coil B at any point.
-----------------------
Question:    "Shorted to What exactly? Shorted back on itself? Because the Built in Diode will do this Half Cycle on the Fet anyway!"

No it wont,if the current flow in the coil is opposite to what it needs to be,due to a magnetic field that is opposite to that of the rotors field.
-----------------------
Question:  "Tinman says he shorts one of his coils at a particular time in his generator's cycle."

Yes,coil B is shorted for part of the rotor segments induced time.
-----------------------
Yes,there is a conduction path from coil B to the load,but no path from the load to coil B.
Coil B dose nothing until Coil A is producing a current flow,and thus S1 must be closed in order for coil B to provide current to follow that conduction path.
Without a load,coil A will lift the voltage in a cap to over 130 volts,but with coil B in operation the mosfet will blow at around 45-50 volts,as it is triggered by the reverse voltage of coil A.
-----------------------

@penno64    I put the above two lines in bold because the maximum gate - source voltage specified for the MOSFET is +/-20V, this is why I indicated the resistors in my schematic as simple means for protection.  Will you attempt some tests with your schematic?

Gyula

tinman

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Re: Tinman's coil shorting circuit
« Reply #13 on: September 17, 2015, 01:41:23 AM »
Hi Jimboot,

Your question was answered by Brad in June if you go back to his posts. See his reply to woopy (Reply #3782 on: June 22, 2015, 12:48:14 PM, page 253) for instance  where he explains that a shorted coil in the right moment works as an electromagnet and he bucks its field with the rotor field, this is what gives some extra torque in the first place and the collection of the collapsed field takes place also and steered to the puffer capacitor.  So Brad shorts stator coil B in the first place to get an increase in rotor torque.

Further quotes from Brad from his other posts:

So here is where im at with V3 of the rotary transformer. Adding the bucking coil setup did indeed increase the overall output of the system-both mechanical and electrical. When  i say bucking coil, i mean a coil that acts as a magnet that can be switched on and off at the right time.  As it is a coil that is being shorted,and thus becomes an electromagnet that pushes against the rotors collapsing field just at the right time. This field also travels around the stator core,and boost the field within the secondary(generating)coil that provides the power for the globe.
So we do have a coil that is bucking both against the rotor's field and also the field of the generating coil.
-----------------------
I am using a bucking field effect between the rotor and coil B,not between coil B and coil A.

Coil B's current can flow into the cap along with coil A's current for a brief period of time,but coil A's current cannot flow into coil B at any point.
-----------------------
Question:    "Shorted to What exactly? Shorted back on itself? Because the Built in Diode will do this Half Cycle on the Fet anyway!"

No it wont,if the current flow in the coil is opposite to what it needs to be,due to a magnetic field that is opposite to that of the rotors field.
-----------------------
Question:  "Tinman says he shorts one of his coils at a particular time in his generator's cycle."

Yes,coil B is shorted for part of the rotor segments induced time.
-----------------------
Yes,there is a conduction path from coil B to the load,but no path from the load to coil B.
Coil B dose nothing until Coil A is producing a current flow,and thus S1 must be closed in order for coil B to provide current to follow that conduction path.
Without a load,coil A will lift the voltage in a cap to over 130 volts,but with coil B in operation the mosfet will blow at around 45-50 volts,as it is triggered by the reverse voltage of coil A.
-----------------------

@penno64    I put the above two lines in bold because the maximum gate - source voltage specified for the MOSFET is +/-20V, this is why I indicated the resistors in my schematic as simple means for protection.  Will you attempt some tests with your schematic?

Gyula

What the hell.
After the turn of recent event's,everything is shot to hell anyway.
So here you go. Im sure you can work out the circuit needed from the schematic below.

Jimboot

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Re: Tinman's coil shorting circuit
« Reply #14 on: September 17, 2015, 01:56:52 AM »
Hi Jimboot,

Your question was answered by Brad in June if you go back to his posts. See his reply to woopy (Reply #3782 on: June 22, 2015, 12:48:14 PM, page 253) for instance  where he explains that a shorted coil in the right moment works as an electromagnet and he bucks its field with the rotor field, this is what gives some extra torque in the first place and the collection of the collapsed field takes place also and steered to the puffer capacitor.  So Brad shorts stator coil B in the first place to get an increase in rotor torque.

Further quotes from Brad from his other posts:

So here is where im at with V3 of the rotary transformer. Adding the bucking coil setup did indeed increase the overall output of the system-both mechanical and electrical. When  i say bucking coil, i mean a coil that acts as a magnet that can be switched on and off at the right time.  As it is a coil that is being shorted,and thus becomes an electromagnet that pushes against the rotors collapsing field just at the right time. This field also travels around the stator core,and boost the field within the secondary(generating)coil that provides the power for the globe.
So we do have a coil that is bucking both against the rotor's field and also the field of the generating coil.
-----------------------
I am using a bucking field effect between the rotor and coil B,not between coil B and coil A.

Coil B's current can flow into the cap along with coil A's current for a brief period of time,but coil A's current cannot flow into coil B at any point.
-----------------------
Question:    "Shorted to What exactly? Shorted back on itself? Because the Built in Diode will do this Half Cycle on the Fet anyway!"

No it wont,if the current flow in the coil is opposite to what it needs to be,due to a magnetic field that is opposite to that of the rotors field.
-----------------------
Question:  "Tinman says he shorts one of his coils at a particular time in his generator's cycle."

Yes,coil B is shorted for part of the rotor segments induced time.
-----------------------
Yes,there is a conduction path from coil B to the load,but no path from the load to coil B.
Coil B dose nothing until Coil A is producing a current flow,and thus S1 must be closed in order for coil B to provide current to follow that conduction path.
Without a load,coil A will lift the voltage in a cap to over 130 volts,but with coil B in operation the mosfet will blow at around 45-50 volts,as it is triggered by the reverse voltage of coil A.
-----------------------

@penno64    I put the above two lines in bold because the maximum gate - source voltage specified for the MOSFET is +/-20V, this is why I indicated the resistors in my schematic as simple means for protection.  Will you attempt some tests with your schematic?

Gyula
Thanks Gyula. I've been looking closely at the Alexander patent which does not short the output. Thanks for the references.