looking for a push pull schematic for VTTC
teravolt, Fri Jan 30 2009, 03:08AMI am looking for a schematic for a class B or AB type (push pull) vacume tube coil. has anybody tried this. I'm thinking that it would work like the standerd VTTC but it would use a resonant primary with a center tap. the feedback winding would also have a center tap. I can draw an idia if any body wants. Thanks Nathan B.
Re: looking for a push pull schematic for VTTC
Dr. Drone, Fri Jan 30 2009, 04:17AM
Dr. Drone, Fri Jan 30 2009, 04:17AM
Re: looking for a push pull schematic for VTTC
Coronafix, Fri Jan 30 2009, 06:15AM
Excuse my ignorance Doc, but would it have made any difference if you had wound it bifilar with a centre tap at the base?
Coronafix, Fri Jan 30 2009, 06:15AM
Excuse my ignorance Doc, but would it have made any difference if you had wound it bifilar with a centre tap at the base?
Re: looking for a push pull schematic for VTTC
Dr. Drone, Fri Jan 30 2009, 08:08AM
Dr. Drone, Fri Jan 30 2009, 08:08AM
Re: looking for a push pull schematic for VTTC
teravolt, Wed Feb 04 2009, 04:00AM
here is a basic scematic that I invented from a tube amp shematic and a a picture of a push pull primary. unlike Dr. Sparks primary mine uses only 10 tuns with a center tap with 12awg teflon wire. At one point I used 2 10000pf micas for the primary capacitors. the problem that I had was getting it to oscillate. should there be a quiescent biasing for the grids to get feedback? the plan would be to get it to work like a dual class C
teravolt, Wed Feb 04 2009, 04:00AM
here is a basic scematic that I invented from a tube amp shematic and a a picture of a push pull primary. unlike Dr. Sparks primary mine uses only 10 tuns with a center tap with 12awg teflon wire. At one point I used 2 10000pf micas for the primary capacitors. the problem that I had was getting it to oscillate. should there be a quiescent biasing for the grids to get feedback? the plan would be to get it to work like a dual class C
Re: looking for a push pull schematic for VTTC
Proud Mary, Wed Feb 04 2009, 05:09AM
Why do you want to run a power oscillator in Class A, or Class AB, when Class C offers so much more efficiency?
If you let go of the vertical (contemporary) Tesla model, you'll see that what you are talking about is a high voltage radio frequency transformer, for which a push-pull driver would usually be the circuit of choice. During the valve era, devices of this kind were sometimes used to generate 100kV or so for charging large Marx generators, and driving industrial X-ray tubes.
I would choose one of the heavy-weight transmitting double tetrodes - a few hundred watts - as a good basis for an experimental model, but you will find making a stiff power supply for even a medium power valve circuit of this kind a very expensive business.
If you were able to give a clearer picture of what you have in mind, it might be possible to help you put together something interesting without having to sell your car to pay for it!
I would call the circuit diagram posted above a skeleton circuit, such as one sees in explanatory text books. None of the detail one would expect to see in an engineering drawing is shown. Nothing is done to protect the valves against premature application of the HT (i.e. a heater delay relay) nor against bias failure, against parasitic oscillation, and no meters are shown in grid and anode circuits, without which the tuning of the circuit would be all but impossible.
Valve Push-pull RF power circuits can be tricky to set up correctly, even for the experienced designer, as there is usually quite a big gap between the theoretical model and its realization as stable, effcient, reliable, engineering.
Proud Mary, Wed Feb 04 2009, 05:09AM
Why do you want to run a power oscillator in Class A, or Class AB, when Class C offers so much more efficiency?
If you let go of the vertical (contemporary) Tesla model, you'll see that what you are talking about is a high voltage radio frequency transformer, for which a push-pull driver would usually be the circuit of choice. During the valve era, devices of this kind were sometimes used to generate 100kV or so for charging large Marx generators, and driving industrial X-ray tubes.
I would choose one of the heavy-weight transmitting double tetrodes - a few hundred watts - as a good basis for an experimental model, but you will find making a stiff power supply for even a medium power valve circuit of this kind a very expensive business.
If you were able to give a clearer picture of what you have in mind, it might be possible to help you put together something interesting without having to sell your car to pay for it!
I would call the circuit diagram posted above a skeleton circuit, such as one sees in explanatory text books. None of the detail one would expect to see in an engineering drawing is shown. Nothing is done to protect the valves against premature application of the HT (i.e. a heater delay relay) nor against bias failure, against parasitic oscillation, and no meters are shown in grid and anode circuits, without which the tuning of the circuit would be all but impossible.
Valve Push-pull RF power circuits can be tricky to set up correctly, even for the experienced designer, as there is usually quite a big gap between the theoretical model and its realization as stable, effcient, reliable, engineering.
Re: looking for a push pull schematic for VTTC
teravolt, Wed Feb 04 2009, 08:53PM
Hi Harry, I wanted to do push pull because using paraleling triods can lead to unequal current share and harmonic oscilation betwean the tubes in class C. I have 3 833c and 2 811h from rf electronics. I was reading that Class AB can be more eficent for amplifiers and I wanted to see if any body has done this. I have not decided to do push pull or not. I have read Steve Ward's VTTC page and when he went to 2 tubes the change was not a big one and he had some power balancing to do. any coments are welcome N.B.
teravolt, Wed Feb 04 2009, 08:53PM
Hi Harry, I wanted to do push pull because using paraleling triods can lead to unequal current share and harmonic oscilation betwean the tubes in class C. I have 3 833c and 2 811h from rf electronics. I was reading that Class AB can be more eficent for amplifiers and I wanted to see if any body has done this. I have not decided to do push pull or not. I have read Steve Ward's VTTC page and when he went to 2 tubes the change was not a big one and he had some power balancing to do. any coments are welcome N.B.
Re: looking for a push pull schematic for VTTC
Proud Mary, Wed Feb 04 2009, 09:38PM
Rememeber that valves are high impedance devices, so small differences between them does not cause the runaway "current hogging" that we see with parallel, and slightly unequal semiconductors.
Precautions must be taken against parasitic oscillation whether valves are connected in parallel or in a push-pull configuration. Small chokes of dissimilar values hard up to anode and grid pins are your first line of defence here.
It is true that more harmonics will be radiated by a Class C oscillator unless suitable trap circuitry is used to by-pass unwanted frequencies to Earth.
But unless you place your entire apparatus inside a Faraday carriage you will be radiating considerable amounts of RF energy whatever sort of oscillator you use!
That being said, in a perfectly balanced push-pull oscillator, even order harmonics are, in theory, absent, but in practice will still be present but at low levels compared with those of the odd order.
With the skeleton circuit you have presented above, I would expect it to be quite unstable, the frequency wandering all over the place, with a sort of ragout of assorted RF emissions showing up on the spectrum analyser from LF all the way into the dizzy heights of the VHF.
My suggestion: build this circuit first of all with small power tetrodes, so you can find out how to make it work efficiently, which will certainly involve all sorts of small alterations and additions to the skeleton circuit. Put meters in the anode and grid circuits so you can see what is going on in the circuit. Without them you have only guess work and conjecture.
And why risk the ruin of expensive valves that othewise would have given years of good service?
But I can't do your experiments for you, lad! Good luck with it!
Proud Mary, Wed Feb 04 2009, 09:38PM
teravolt wrote ...
Hi Harry, I wanted to do push pull because using paraleling triods can lead to unequal current share and harmonic oscilation betwean the tubes in class C. I have 3 833c and 2 811h from rf electronics. I was reading that Class AB can be more eficent for amplifiers and I wanted to see if any body has done this. I have not decided to do push pull or not. I have read Steve Ward's VTTC page and when he went to 2 tubes the change was not a big one and he had some power balancing to do. any coments are welcome N.B.
Hi Harry, I wanted to do push pull because using paraleling triods can lead to unequal current share and harmonic oscilation betwean the tubes in class C. I have 3 833c and 2 811h from rf electronics. I was reading that Class AB can be more eficent for amplifiers and I wanted to see if any body has done this. I have not decided to do push pull or not. I have read Steve Ward's VTTC page and when he went to 2 tubes the change was not a big one and he had some power balancing to do. any coments are welcome N.B.
Rememeber that valves are high impedance devices, so small differences between them does not cause the runaway "current hogging" that we see with parallel, and slightly unequal semiconductors.
Precautions must be taken against parasitic oscillation whether valves are connected in parallel or in a push-pull configuration. Small chokes of dissimilar values hard up to anode and grid pins are your first line of defence here.
It is true that more harmonics will be radiated by a Class C oscillator unless suitable trap circuitry is used to by-pass unwanted frequencies to Earth.
But unless you place your entire apparatus inside a Faraday carriage you will be radiating considerable amounts of RF energy whatever sort of oscillator you use!
That being said, in a perfectly balanced push-pull oscillator, even order harmonics are, in theory, absent, but in practice will still be present but at low levels compared with those of the odd order.
With the skeleton circuit you have presented above, I would expect it to be quite unstable, the frequency wandering all over the place, with a sort of ragout of assorted RF emissions showing up on the spectrum analyser from LF all the way into the dizzy heights of the VHF.
My suggestion: build this circuit first of all with small power tetrodes, so you can find out how to make it work efficiently, which will certainly involve all sorts of small alterations and additions to the skeleton circuit. Put meters in the anode and grid circuits so you can see what is going on in the circuit. Without them you have only guess work and conjecture.
And why risk the ruin of expensive valves that othewise would have given years of good service?
But I can't do your experiments for you, lad!
Good luck with it! Re: looking for a push pull schematic for VTTC
Dr. Drone, Wed Feb 04 2009, 09:43PM
Dr. Drone, Wed Feb 04 2009, 09:43PM
Re: looking for a push pull schematic for VTTC
teravolt, Thu Feb 05 2009, 06:27AM
Thanks Herry and Dr. Spark for your input. Dr. Spark If you include my experience with teslas it would be 90 years. Herry and Dr. Spark, in a oscillator circuit the thing that creates oscilation is gain and positive feadback. My skeleton circuit is a crude way of getting out an idia. The plan is to feed energy from the secondary to drive the grids as moast VTTC's accept out of phase. Tuning will be a bitch and some expierimenting will be necisary. I have built the aperatus with 811h's and power supplies with mica caps and could not get it to oscillate. Getting it to oscillate properly meens that it may have pretuned to the fundimental of the secondary or lower pol in the event of frequency splitting. Also the Q of the circuit and the way it is built will help. In moast VTTC's the primary uses many turns in the primary but I found that in my later experimination only a few turns like in the picture the harmonics could be reduced. hopfuly I can get some meaning full data to extend this conversation. let me know if my ramblings mean any thing to you Nathan B.
teravolt, Thu Feb 05 2009, 06:27AM
Thanks Herry and Dr. Spark for your input. Dr. Spark If you include my experience with teslas it would be 90 years. Herry and Dr. Spark, in a oscillator circuit the thing that creates oscilation is gain and positive feadback. My skeleton circuit is a crude way of getting out an idia. The plan is to feed energy from the secondary to drive the grids as moast VTTC's accept out of phase. Tuning will be a bitch and some expierimenting will be necisary. I have built the aperatus with 811h's and power supplies with mica caps and could not get it to oscillate. Getting it to oscillate properly meens that it may have pretuned to the fundimental of the secondary or lower pol in the event of frequency splitting. Also the Q of the circuit and the way it is built will help. In moast VTTC's the primary uses many turns in the primary but I found that in my later experimination only a few turns like in the picture the harmonics could be reduced. hopfuly I can get some meaning full data to extend this conversation. let me know if my ramblings mean any thing to you Nathan B.
Re: looking for a push pull schematic for VTTC
Dr Hankenstein, Thu Feb 05 2009, 08:52PM
Last year I tried the push-pull configuration but ran into some interesting snags:
First of all, there was so much primary wire involved in the helix coil that it had a serious shunting effect on the power. That is to say the primary seemed to be way over-coupled (excessive mutual coupling) resulting in very low power output.
My next step around this was to try a pancake coil. This was abandoned due to inadequate L(uh) to C(uuf) ratio physically possible to tranfer any power to the secondary efficiently.
I found the classic single-ended design from the 1940's (The one that is on Steve Ward's website) to work the best.
All these brilliant ideas (or lack of performance of) eventually led to the construction of the "Super 833C" Multimode prototype coil, which is of classic design, and yet can be quickly configured for ticker coil, direct grid drive, and can be grid or cathode modulated. (This portion of the discussion is off topic)
Basically the push-pull configuration was abandoned due to complexity and excessive parts count for the theoretical "massive" gain in performance. Push-Pull Vacuum Tube Tesla Coils appear to be a completly different animal compared to their "audio" counterpart.
I have written some extensive notes on tests performed in my pursuit of a push-pull tank circuit and it boils down to:
If you want:
Least amount of headaches
Best performance
Least amount of parts
Simple design.........................stick with the classic VTTC!
Believe me, if RF push-pull circuits were so much better than singe ended; They (ham radio guys) wouldn't have abandened them in the early 1950's! They actually used balanced ladder-line to feed their antennas with a single-ended RF amplifier and a balanced-output antenna coupler....so it really wasn't push-pull in the first place! Check the ARRL handbook of the era.
Hank
Dr Hankenstein, Thu Feb 05 2009, 08:52PM
Last year I tried the push-pull configuration but ran into some interesting snags:
First of all, there was so much primary wire involved in the helix coil that it had a serious shunting effect on the power. That is to say the primary seemed to be way over-coupled (excessive mutual coupling) resulting in very low power output.
My next step around this was to try a pancake coil. This was abandoned due to inadequate L(uh) to C(uuf) ratio physically possible to tranfer any power to the secondary efficiently.
I found the classic single-ended design from the 1940's (The one that is on Steve Ward's website) to work the best.
All these brilliant ideas (or lack of performance of) eventually led to the construction of the "Super 833C" Multimode prototype coil, which is of classic design, and yet can be quickly configured for ticker coil, direct grid drive, and can be grid or cathode modulated. (This portion of the discussion is off topic)
Basically the push-pull configuration was abandoned due to complexity and excessive parts count for the theoretical "massive" gain in performance. Push-Pull Vacuum Tube Tesla Coils appear to be a completly different animal compared to their "audio" counterpart.
I have written some extensive notes on tests performed in my pursuit of a push-pull tank circuit and it boils down to:
If you want:
Least amount of headaches
Best performance
Least amount of parts
Simple design.........................stick with the classic VTTC!
Believe me, if RF push-pull circuits were so much better than singe ended; They (ham radio guys) wouldn't have abandened them in the early 1950's! They actually used balanced ladder-line to feed their antennas with a single-ended RF amplifier and a balanced-output antenna coupler....so it really wasn't push-pull in the first place! Check the ARRL handbook of the era.
Hank
Re: looking for a push pull schematic for VTTC
Proud Mary, Thu Feb 05 2009, 10:41PM
In fact, the last generation of medium power transmitter valves to have been designed were all designed for push-pull operation (Mullard's famous QQV0 double tetrode series for example only) and continued to be used in new RF designs well into the 1970s.
A necessary condition of RF push-pull operation - but one surprisingly often missed by beginners - is that the circuit requires twice as much RF drive as either a single valve - or two valves in simple parallel - which has obvious implications for oscillator design.
Proud Mary, Thu Feb 05 2009, 10:41PM
Dr Hankenstein wrote ...
Believe me, if RF push-pull circuits were so much better than singe ended; They (ham radio guys) wouldn't have abandened them in the early 1950's! They actually used balanced ladder-line to feed their antennas with a single-ended RF amplifier and a balanced-output antenna coupler....so it really wasn't push-pull in the first place! Check the ARRL handbook of the era.
Believe me, if RF push-pull circuits were so much better than singe ended; They (ham radio guys) wouldn't have abandened them in the early 1950's! They actually used balanced ladder-line to feed their antennas with a single-ended RF amplifier and a balanced-output antenna coupler....so it really wasn't push-pull in the first place! Check the ARRL handbook of the era.
In fact, the last generation of medium power transmitter valves to have been designed were all designed for push-pull operation (Mullard's famous QQV0 double tetrode series for example only) and continued to be used in new RF designs well into the 1970s.
A necessary condition of RF push-pull operation - but one surprisingly often missed by beginners - is that the circuit requires twice as much RF drive as either a single valve - or two valves in simple parallel - which has obvious implications for oscillator design.
Re: looking for a push pull schematic for VTTC
Coronafix, Fri Feb 06 2009, 01:58AM
Don't know if this helps, but Tesla had a push pull configuration like this.
Coronafix, Fri Feb 06 2009, 01:58AM
Don't know if this helps, but Tesla had a push pull configuration like this.
Re: looking for a push pull schematic for VTTC
Herr Zapp, Fri Feb 06 2009, 02:08AM
Coronafix -
As drawn, it looks like the electrode orientation on your RSG would simply short both tank capacitors simultaneously, with no current through the primary coil.
Regards,
Herr zapp
Herr Zapp, Fri Feb 06 2009, 02:08AM
Coronafix -
As drawn, it looks like the electrode orientation on your RSG would simply short both tank capacitors simultaneously, with no current through the primary coil.
Regards,
Herr zapp
Re: looking for a push pull schematic for VTTC
teravolt, Fri Feb 06 2009, 06:36AM
Herr Zapp, Coronafix has a good idia, can 2 tubes be done in half bridge? the driving of two half bridge tubes would take a lot of enginearing.
I was also thinking that it may be puasible drive the tubes with half bridge of mosfets and use another type of feed back using electronics eliminating the top pick off coil.
another thing that may be going on is frequency spliting like in a DRSSTC and tuning might be tricky with out a spectrum analizer or a clear undrestang.
I have found that it is pausible to replace the tubes with mosfets and use a standard push pull oscillator driver to make some analisis.
I have made a modified scematic of Steve's famus dual schematic for conversation sake and a schematic of the fet circuit that I was playing with. the mosfet circuit works and oscillates with 20 in and about 2000 out. I believe that the concept would work
Does any body know if there is a quiesant bias voltage for grids that will pramote oscilation in schematic 3?
please feal free to ask questions. N.B.
teravolt, Fri Feb 06 2009, 06:36AM
Herr Zapp, Coronafix has a good idia, can 2 tubes be done in half bridge? the driving of two half bridge tubes would take a lot of enginearing.
I was also thinking that it may be puasible drive the tubes with half bridge of mosfets and use another type of feed back using electronics eliminating the top pick off coil.
another thing that may be going on is frequency spliting like in a DRSSTC and tuning might be tricky with out a spectrum analizer or a clear undrestang.
I have found that it is pausible to replace the tubes with mosfets and use a standard push pull oscillator driver to make some analisis.
I have made a modified scematic of Steve's famus dual schematic for conversation sake and a schematic of the fet circuit that I was playing with. the mosfet circuit works and oscillates with 20 in and about 2000 out. I believe that the concept would work
Does any body know if there is a quiesant bias voltage for grids that will pramote oscilation in schematic 3?
please feal free to ask questions. N.B.
Re: looking for a push pull schematic for VTTC
Proud Mary, Fri Feb 06 2009, 08:46AM
It is difficult to know what more can be said in this thread, except to say that any of the basic valve push-pull power oscillator configurations could be made to work well to drive a resonant secondary.
What looks odd to me is the transition from a symmetrical push-pull driven primary to an unbalanced resonant secondary.
I am most certainly not a Tesla coil designer, but I should have thought the secondary should have an earthed centre tap, so the impedance presented to the driver primaries remains in balance. The full potential would then be developed across the opposing ends of the secondary, but with only half that in relation to Earth, a distinct advantage from an insulation point of view.
Proud Mary, Fri Feb 06 2009, 08:46AM
It is difficult to know what more can be said in this thread, except to say that any of the basic valve push-pull power oscillator configurations could be made to work well to drive a resonant secondary.
What looks odd to me is the transition from a symmetrical push-pull driven primary to an unbalanced resonant secondary.
I am most certainly not a Tesla coil designer, but I should have thought the secondary should have an earthed centre tap, so the impedance presented to the driver primaries remains in balance. The full potential would then be developed across the opposing ends of the secondary, but with only half that in relation to Earth, a distinct advantage from an insulation point of view.
Re: looking for a push pull schematic for VTTC
Herr Zapp, Fri Feb 06 2009, 06:17PM
Harry -
I think you have raised a very interesting point here about the ability of a push-pull driver with "symmetrical" primary to drive a unipolar secondary.
I suspect that both Dr. Spark's and Dr. Hankenstein's push-pull VTTC experiments utilized a (more or less) symmetrical center-tapped primary driving a vertical, grounded-base secondary. Each "leg" of the primary coil may have have ended up with significantly different coupling to secondary, capacitance to ground, etc.
I think it would be interesting to look at the design of a horizontal bipolar VTTC, possibly with the secondary split into two sections that could independently be moved axially to adjust pri-sec coupling.
This could provide a truly symmetrical, "balanced" design with mirror-image inductance, capacitance and coupling characteristics for both halves of the drive circuit.
Regards,
Herr Zapp
Herr Zapp, Fri Feb 06 2009, 06:17PM
Harry -
I think you have raised a very interesting point here about the ability of a push-pull driver with "symmetrical" primary to drive a unipolar secondary.
I suspect that both Dr. Spark's and Dr. Hankenstein's push-pull VTTC experiments utilized a (more or less) symmetrical center-tapped primary driving a vertical, grounded-base secondary. Each "leg" of the primary coil may have have ended up with significantly different coupling to secondary, capacitance to ground, etc.
I think it would be interesting to look at the design of a horizontal bipolar VTTC, possibly with the secondary split into two sections that could independently be moved axially to adjust pri-sec coupling.
This could provide a truly symmetrical, "balanced" design with mirror-image inductance, capacitance and coupling characteristics for both halves of the drive circuit.
Regards,
Herr Zapp
Re: looking for a push pull schematic for VTTC
Coronafix, Sat Feb 07 2009, 12:27AM
As noted this was Tesla's circuit, not mine. He also had a "regulator" between the RSG and primary, which I guess is a choke. Aug 17 1899
Coronafix, Sat Feb 07 2009, 12:27AM
Herr Zapp wrote ...
Coronafix -
As drawn, it looks like the electrode orientation on your RSG would simply short both tank capacitors simultaneously, with no current through the primary coil.
Regards,
Herr zapp
Coronafix -
As drawn, it looks like the electrode orientation on your RSG would simply short both tank capacitors simultaneously, with no current through the primary coil.
Regards,
Herr zapp
As noted this was Tesla's circuit, not mine. He also had a "regulator" between the RSG and primary, which I guess is a choke. Aug 17 1899
Re: looking for a push pull schematic for VTTC
Dr. Drone, Sat Feb 07 2009, 03:06AM
Dr. Drone, Sat Feb 07 2009, 03:06AM
Re: looking for a push pull schematic for VTTC
teravolt, Sat Feb 07 2009, 06:42AM
Herr Zapp it sounds like you are describing a half wave VTTC witch sounds like a fun project, I may concider it. If it works with mosfets it should work with tubes. I just have to do some more expierimenting. I chose this epieriment not because it might be hard but because I think it has not been done. I may fail and come to the same conclusions, I may not.
can any body give me an idia about a tickler coil thanks
as a side conversation can any body tell me why sword like sparks only come from VTTC's and some SSTC's
teravolt, Sat Feb 07 2009, 06:42AM
Herr Zapp it sounds like you are describing a half wave VTTC witch sounds like a fun project, I may concider it. If it works with mosfets it should work with tubes. I just have to do some more expierimenting. I chose this epieriment not because it might be hard but because I think it has not been done. I may fail and come to the same conclusions, I may not.
can any body give me an idia about a tickler coil thanks
as a side conversation can any body tell me why sword like sparks only come from VTTC's and some SSTC's
Re: looking for a push pull schematic for VTTC
Herr Zapp, Sat Feb 07 2009, 07:05AM
Dr Spark -
Certainly you could build two completely "independent" tank circuits, but having a symmetrical center-tapped primary driving a symmetrically-terminated secondary should allow use of a conventional push-pull vacuum-tube driver topology.
Large triodes in push-pull layouts have been used for years in high power industrial induction heating systems. D. Sharpe was kind enough to provide several US patent numbers showing power oscillators with push-pull drivers:
2,464,252 (J. Moore; 3/15/1948)
2,540,275 (E. Mittelman of EIMAC fame; 2/6/1951)
2,579,374 (D. Edwards; 12/18/1951)
3,119,971 (M. Cleland, etal; 1/28/1964)
3,638,657 (H. Mettler; 2/1/1972)
3,747,013 (H. Mettler; 7/17/1973)
These patents can be viewed at no cost from the US patent office website (
). Read the instructions on downloading the appropriate viewing software.
Regards,
Herr Zapp
Herr Zapp, Sat Feb 07 2009, 07:05AM
Dr Spark -
Certainly you could build two completely "independent" tank circuits, but having a symmetrical center-tapped primary driving a symmetrically-terminated secondary should allow use of a conventional push-pull vacuum-tube driver topology.
Large triodes in push-pull layouts have been used for years in high power industrial induction heating systems. D. Sharpe was kind enough to provide several US patent numbers showing power oscillators with push-pull drivers:
2,464,252 (J. Moore; 3/15/1948)
2,540,275 (E. Mittelman of EIMAC fame; 2/6/1951)
2,579,374 (D. Edwards; 12/18/1951)
3,119,971 (M. Cleland, etal; 1/28/1964)
3,638,657 (H. Mettler; 2/1/1972)
3,747,013 (H. Mettler; 7/17/1973)
These patents can be viewed at no cost from the US patent office website (
). Read the instructions on downloading the appropriate viewing software.Regards,
Herr Zapp
Re: looking for a push pull schematic for VTTC
teravolt, Sun Feb 08 2009, 02:41AM
thanks Herr Zapp I found a 1956 radio amateur's handbook. may look at patents later
teravolt, Sun Feb 08 2009, 02:41AM
thanks Herr Zapp I found a 1956 radio amateur's handbook. may look at patents later
Re: looking for a push pull schematic for VTTC
Dr Hankenstein, Sun Feb 08 2009, 04:37PM
Herr Zapp,
Your idea is fantabulous! I never considered the independent horizontal "bipolar" scheme as you mentioned. As you can see, a few of us have tried all sorts of variations (using a single-ended secondary) to no avail. I don't know where the "modified Steve Ward" schematics shown above came from; but I tried every one of those. The results are all part of the previous thread I mentioned earlier that didn't work for me. I have documented most of my "failed work" Maybe I missed something. I am considering adding the "failed" attempt documentation to the website, because the finished product took a hard left turn compared to the original dream. Documenting my failed attempts doesn't bother me in the least. Like I always say "If you dare dream it, build it!" Dr. Spark and I worked on this project for nearly a year. The problem was...this was virgin territory...no information anywhere...probably for good reason..maybe it didn't work for our elders either!!
A good lesson to learn: I have an old ham radio friend; he is now 92 yrs old. He is an extrordinary high powered amplifier builder. I was building a dual 4CX250B amplifer at the time and had some questions about the tank coil configuration and additional coil for 160meters. He proceeded to open William Orr's Handbook of Radio Electronics to a table of coil information with power/plate voltage ratios,etc. and said "get this book...they have already done all the hard work for you and this works the best! don't waste your time re-inventing the wheel" He was right! They never seem to publish the mistakes..only what works!
That being said; good luck on the "modified" single ended design. I would definitly be very interested in seeing the bipolar version as there may be some merit in this. I can't say whether it will work as I haven't tried it either.
Good luck,
Hank
Dr Hankenstein, Sun Feb 08 2009, 04:37PM
Herr Zapp,
Your idea is fantabulous! I never considered the independent horizontal "bipolar" scheme as you mentioned. As you can see, a few of us have tried all sorts of variations (using a single-ended secondary) to no avail. I don't know where the "modified Steve Ward" schematics shown above came from; but I tried every one of those. The results are all part of the previous thread I mentioned earlier that didn't work for me. I have documented most of my "failed work" Maybe I missed something. I am considering adding the "failed" attempt documentation to the website, because the finished product took a hard left turn compared to the original dream. Documenting my failed attempts doesn't bother me in the least. Like I always say "If you dare dream it, build it!" Dr. Spark and I worked on this project for nearly a year. The problem was...this was virgin territory...no information anywhere...probably for good reason..maybe it didn't work for our elders either!!
A good lesson to learn: I have an old ham radio friend; he is now 92 yrs old. He is an extrordinary high powered amplifier builder. I was building a dual 4CX250B amplifer at the time and had some questions about the tank coil configuration and additional coil for 160meters. He proceeded to open William Orr's Handbook of Radio Electronics to a table of coil information with power/plate voltage ratios,etc. and said "get this book...they have already done all the hard work for you and this works the best! don't waste your time re-inventing the wheel" He was right! They never seem to publish the mistakes..only what works!
That being said; good luck on the "modified" single ended design. I would definitly be very interested in seeing the bipolar version as there may be some merit in this. I can't say whether it will work as I haven't tried it either.
Good luck,
Hank
Re: looking for a push pull schematic for VTTC
Dr. Drone, Sun Feb 08 2009, 06:44PM
Dr. Drone, Sun Feb 08 2009, 06:44PM
Re: looking for a push pull schematic for VTTC
Herr Zapp, Sun Feb 08 2009, 08:21PM
Drs. Hankenstein & Spark -
I'm trying to get a small "proof-of-concept" horizontal "bipolar" push-pull VTTC put together by WWT'09.......
Candidate triodes include 572-B, 805, or 304TL. Layout includes fixed center-tapped primary with dual feedback windings on the primary coilform outboard of the actual primary, split secondary with axial coupling adjustment, and "skeleton" toroids fabbed from rings of 1/4" or 3/8" dia stainless-steel tubing. I've got all the parts on-hand, the challenge will be to find time for assembly & tuning .....
Dr. Hankenstein - The book you mentioned by William Orr ...... do you have a copy? If so, can you tell me the exact title, or the ISBN#? I can find his "VHF Handbook" (ISBN unknown), and his "Radio Handbook" (ISBN 0672224240), but no "Handbook of Radio Electronics".
Regards,
Herr Zapp
Herr Zapp, Sun Feb 08 2009, 08:21PM
Drs. Hankenstein & Spark -
I'm trying to get a small "proof-of-concept" horizontal "bipolar" push-pull VTTC put together by WWT'09.......
Candidate triodes include 572-B, 805, or 304TL. Layout includes fixed center-tapped primary with dual feedback windings on the primary coilform outboard of the actual primary, split secondary with axial coupling adjustment, and "skeleton" toroids fabbed from rings of 1/4" or 3/8" dia stainless-steel tubing. I've got all the parts on-hand, the challenge will be to find time for assembly & tuning .....
Dr. Hankenstein - The book you mentioned by William Orr ...... do you have a copy? If so, can you tell me the exact title, or the ISBN#? I can find his "VHF Handbook" (ISBN unknown), and his "Radio Handbook" (ISBN 0672224240), but no "Handbook of Radio Electronics".
Regards,
Herr Zapp
Re: looking for a push pull schematic for VTTC
teravolt, Sun Feb 08 2009, 08:51PM
hello Herr Zapp and others I have done some reading in radio amature handbook 1956 and re read Steve's page again and come up with my starting point. The changes I have done to Steve's scematic are :
1: less turns on the secondary is for higher Q and higher current, 12 AWG
2: I reduced the grid feed back resister by half because there will be twice the negitive cycles charging up the grid feed back capacitor
3: L2 the number of turn are subjective maby 25 turns with a center tap
4: notce the phaseing dots
the changes were done with paint
any Questions are welcome N.B.
teravolt, Sun Feb 08 2009, 08:51PM
hello Herr Zapp and others I have done some reading in radio amature handbook 1956 and re read Steve's page again and come up with my starting point. The changes I have done to Steve's scematic are :
1: less turns on the secondary is for higher Q and higher current, 12 AWG
2: I reduced the grid feed back resister by half because there will be twice the negitive cycles charging up the grid feed back capacitor
3: L2 the number of turn are subjective maby 25 turns with a center tap
4: notce the phaseing dots
the changes were done with paint
any Questions are welcome N.B.
Re: looking for a push pull schematic for VTTC
Proud Mary, Sun Feb 08 2009, 09:06PM
Here is a modern circuit example of a push-pull power triode Colpitts oscillator driving a balanced resonant HV transformer:
CONSTRUCTION & TESTING OF 50kW/120kHz OSCILLATOR FOR
3MeV, 30kW DC ACCELERATOR
Proud Mary, Sun Feb 08 2009, 09:06PM
Here is a modern circuit example of a push-pull power triode Colpitts oscillator driving a balanced resonant HV transformer:
CONSTRUCTION & TESTING OF 50kW/120kHz OSCILLATOR FOR
3MeV, 30kW DC ACCELERATOR
Re: looking for a push pull schematic for VTTC
Dr. Drone, Mon Feb 09 2009, 03:52AM
Dr. Drone, Mon Feb 09 2009, 03:52AM
Re: looking for a push pull schematic for VTTC
Dr Hankenstein, Mon Feb 09 2009, 04:42AM
Herr Zapp; Are you kidding me? You're actually bringing a real coil this year??! Bride of Hankenstein doesn't believe it's true! For that you will definitely be rewarded with a genuine "wheel of fire" corona ring! (Since you've already got the jugs)
BTW: You're right, William Ore's book is titled "Radio Handbook". I have a copy myself and highly recommend it. Couldn't remember the exact name as my books are still in boxes.
Regards,
Hank
Dr Hankenstein, Mon Feb 09 2009, 04:42AM
Herr Zapp; Are you kidding me? You're actually bringing a real coil this year??! Bride of Hankenstein doesn't believe it's true! For that you will definitely be rewarded with a genuine "wheel of fire" corona ring! (Since you've already got the jugs)
BTW: You're right, William Ore's book is titled "Radio Handbook". I have a copy myself and highly recommend it. Couldn't remember the exact name as my books are still in boxes.
Regards,
Hank
Re: looking for a push pull schematic for VTTC
christensenda, Tue Oct 18 2011, 08:43PM
I know this thread is really old but I was wondering what ever happened with the push pull VTTC. Did anyone ever confirm/deny whether the circuit worked? If so could someone post a picture of the schematic/coil I might be interested in building a coil like this in the near future if its doable
christensenda, Tue Oct 18 2011, 08:43PM
I know this thread is really old but I was wondering what ever happened with the push pull VTTC. Did anyone ever confirm/deny whether the circuit worked? If so could someone post a picture of the schematic/coil I might be interested in building a coil like this in the near future if its doable
Re: looking for a push pull schematic for VTTC
teravolt, Wed Oct 19 2011, 07:35PM
well alot of rf amplifiers use class AB for lower distortion and increased efisency but a tesla is harder to tune. I dont think that it is impausible but you need the right equpment like dual tunin caps ect. to tune
teravolt, Wed Oct 19 2011, 07:35PM
well alot of rf amplifiers use class AB for lower distortion and increased efisency but a tesla is harder to tune. I dont think that it is impausible but you need the right equpment like dual tunin caps ect. to tune
Re: looking for a push pull schematic for VTTC
teravolt, Thu Oct 20 2011, 01:23PM
perhaps it may be easier to drive the tubes directlly using electonics ie half bridge and a oscilator with some zero crossing feedback insted of a armstrong oscilator setup. christensenda do you have any ideas
teravolt, Thu Oct 20 2011, 01:23PM
perhaps it may be easier to drive the tubes directlly using electonics ie half bridge and a oscilator with some zero crossing feedback insted of a armstrong oscilator setup. christensenda do you have any ideas
Re: looking for a push pull schematic for VTTC
christensenda, Thu Oct 20 2011, 06:06PM
Am afraid my knowledge in vacuum tubes and oscillators is quite elementary, and solid state is non-existent. I was simply looking through some of the old threads and this seemed like an interesting idea and just wondered if anyone ever had any concrete results.
christensenda, Thu Oct 20 2011, 06:06PM
Am afraid my knowledge in vacuum tubes and oscillators is quite elementary, and solid state is non-existent. I was simply looking through some of the old threads and this seemed like an interesting idea and just wondered if anyone ever had any concrete results.
Re: looking for a push pull schematic for VTTC
zilipoper, Thu Oct 20 2011, 11:30PM
this is grand
zilipoper, Thu Oct 20 2011, 11:30PM
this is grand
Re: looking for a push pull schematic for VTTC
teravolt, Fri Oct 21 2011, 03:03AM
I don't know whether others who tried this experiment got frustrated or whether they had success it is definitely not for beginners. but personaly any thing can be done with enough persistance.
what are you wanting to build
teravolt, Fri Oct 21 2011, 03:03AM
christensenda wrote ...
Am afraid my knowledge in vacuum tubes and oscillators is quite elementary, and solid state is non-existent. I was simply looking through some of the old threads and this seemed like an interesting idea and just wondered if anyone ever had any concrete results.
Am afraid my knowledge in vacuum tubes and oscillators is quite elementary, and solid state is non-existent. I was simply looking through some of the old threads and this seemed like an interesting idea and just wondered if anyone ever had any concrete results.
I don't know whether others who tried this experiment got frustrated or whether they had success it is definitely not for beginners. but personaly any thing can be done with enough persistance.
what are you wanting to build
Re: looking for a push pull schematic for VTTC
christensenda, Fri Oct 21 2011, 09:48AM
Well, last summer I built a single 811A. I would like to either build a larger VTTC or just build a staccato board for my existing one or an entirely new one. I havent built any complex PCBs before though. I figured that VTTCs' would be a small step towards solid state. Anything will be on hold for some time as seeing as I am currently studying abroad in Germany.
christensenda, Fri Oct 21 2011, 09:48AM
Well, last summer I built a single 811A. I would like to either build a larger VTTC or just build a staccato board for my existing one or an entirely new one. I havent built any complex PCBs before though. I figured that VTTCs' would be a small step towards solid state. Anything will be on hold for some time as seeing as I am currently studying abroad in Germany.
Print this page