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Author Topic: Vaccum Tube Amplifier Schematic Needed  (Read 8062 times)
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I need a schematic to amplify low-voltage DC square waves (around 5V) -- for example from a LTC6904, 555 timer or other IC -- to drive around 60V - 100V DC square wave.

I want to use a vaccum triode -- perhaps a 12AX7, since these seem plentiful and have good amplification factor
http://en.wikipedia.org/wiki/12AX7

What I need is very fast transit times  -- for example , the LTC6904 supports 1ns rise and fall times, so capturing this speed would be nice.   MOSFET drives are cumbersome, the SMT tech is annoying, and especially in this application where I do not need to sink lots of current.   

I've found the following schematics, but I need some recommendations:

Common-cathode stage, fully-bypassed cathode:


Common-cathode stage, unbypassed cathode:


source:
http://www.aikenamps.com/Equations.htm

Thanks
   
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Posts: 336
Feynman,

Take a look over here:

http://www.overunity.com/index.php?PHPSESSID=784e9f51fe8e38499658926963443406&topic=2300.msg276959#new

Bruce et. al. has already designed a tube amplifier for his TPU research.

GL.
   
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Feynman
Please see post #144 from Tak 22[very cool guy]
On TK Thread here http://www.overunityresearch.com/index.php?topic=237.msg11847;topicseen#msg11847

Thanks
Chet
   
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What I need is very fast transit times  -- for example , the LTC6904 supports 1ns rise and fall times, so capturing this speed would be nice.   MOSFET drives are cumbersome, the SMT tech is annoying, and especially in this application where I do not need to sink lots of current.  


How much current you'll need at the output will depend on how much capacitance the load presents.  To achieve a 0~100V transition in 1nS, you will find, requires very sophisticated circuitry...and I mean VERY.

If your load presents say, 1nF stray capacitance, you'll need on the order of 100 AMPS to get a 100V change across it in 1nS.  If it's only 100pF, you'll still need 10A to get 1nS rise/fall times.

And all that assumes that your tube amplifier switches full on and off (and is push-pull, able to source and sink high currents) in zero time.  Even if your load is a coil, it will have some significant parasitic capacitance...probably on the order of 100pF to several nF.  And be sure to add the tube or MOSFET output capacitance to that, and any connecting cable capacitance, too.

You are asking for a lot.  I very seriously doubt you will find any "off-the-shelf" schematic (tube or otherwise) capable of achieving 1nS rise and fall times with 100V transitions.  It's more like a very sophisticated physics experiment than a "cookbook" circuit.  Even 10nS rise/fall times is a severe design exercise.

Humbugger

   
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Feynman
See also
http://www.overunityresearch.com/index.php?topic=17.0
Member here calledTurbo aka Marco, XSNRG and maybe Terbo  at OU.com
Was pissed at Poynt [moderator here] for not being more receptive towards this thread.
Claimed to have the goods.
somehthing to do with the Correa PAGD

I have found Marco to be a really nice guy at times!
Other times he gets a bit testy!

Chet
   
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Thanks guys ; this discussion has turned out way more interesting than I expected.  I have taken a look at all the links that were posted -- including this patent by Correa, which reminds me alot of Moray upon first glance.

@ramset
Thanks for the info on electron secondary emission .  There are alot of processes in nature that are 'OU'.  The question are 1) What is the simplest , cheapest, most replicable OU device we can make to prove COP>1  (a selfrunner essentially -- no solar panels! ;), and 2) What is the simplest, cheapest, most replicable OU device we can make that produces usable levels of power?

@groundloop
Thanks.   After looking at what's involved in creating a tube DC  signal amp, I think I will stick with solid-state!

@humbugger
Thanks for the technical advice Humbugger.  After doing more research, I don't think tubes are appropriate for my application  (since my signal is DC instead of AC).  Also I could potentially have large output capacitance.


---
I think what I'm going to have to do is use the DRF1200A integrated MOSFET and driver.

DRF1200 MOSFET/driver hybrid

The DRF1200 MOSFET driver hybrid. This hybrid includes a high power gate driver and
the power MOSFET. It was designed to provide the system designer increased flexibility
and lowered cost over a non-integrated solution

DRIVER FEATURES
• Switching Frequency: DC TO 30MHz
• Low Pulse Width Distortion
• Single Power Supply
• 3V CMOS Schmitt Trigger Input 1V
Hysteresis
• Drivers > 3nF

MOSFET FEATURES
• Switching Frequency: DC TO 30MHz
• Switching Speed 3-4ns
• BVds = 1kV
• Ids = 13A avg.
• Rds(on) ≤ 1 Ohm
• PD = 350W

http://www.microsemi.com/datasheets/DRF1200_A.pdf

By the way, when I say '1ns rise/fall time' I mean that as a goal.   I've found that you usually end up with about 10x less than what you shoot for when all is said and done (high-speed buffers, etc).  If I get 10-20ns rise time/fall time overall I'll be happy.

I haven't decided what I'll use as the PWM signal generator...function generator chips do not have the level of performance and control I need (sub-500ns PWM, <10% duty cycle, phase lock). I think I'll probably use an Arduino (Atmel AtmegXX) with custom programed interrupts in C -- or perhaps even something faster like an ARM or Intel Single-Board Computer.   I want the ability to switch and amplify 500ns duration pulses with a resolution of 50ns or better, and amplify these pulses to around 100V or more.

I also want to be able create three or four lines of sync'd pulses with variable phase between them (0 - 360 degrees), the possibility of keeping the frequency the same across all signal generators -- or making them harmonic multiples , f*2, f*4 etc -- yet low duty cycle.  The output will be a coil, either connected or unconnected (floating).  

In case you haven't figured it out from the above,  I'm basically copying the Bob Boyce TPU.  I think between the documents I already posted (Bob_Boyce_TPU.pdf) and this document:
http://www.econologie.info/share/partager/1224169776fEjVNG.pdf

I have enough information to replicate Boyce's OU setup.  The only thing I'm concerned with now is experimenting in my room or office in case the whole setup burns up from inducing a scalar flux in the toroid.  I might rent some lab space.
   
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Feynman
PLEASE SEE,
http://www.overunity.com/index.php?PHPSESSID=1f407df38afc410c5b3fbd7baddf2fc7&topic=3628.msg277142#new,

I don't think he'll[Terbo] talk about this here ?[Not sure]
And I just aggravate him because I really can't do a replication attempt[clueless on gas's]
He is a cool guy.............

Chet

   
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